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Autism

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Definition:
Autism is a brain development disorder that is characterized by impaired social interaction and communication, and restricted and repetitive behavior, all starting before a child is three years old. This set of signs distinguishes autism from milder autism spectrum disorders (ASD) such as pervasive developmental disorder not otherwise specified (PDD-NOS).

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Autism has a strong genetic basis, although the genetics of autism are complex and it is unclear whether ASD is explained more by multigene interactions or by rare mutations. In rare cases, autism is strongly associated with agents that cause birth defects. Other proposed causes, such as childhood vaccines, are controversial; the vaccine hypotheses lack convincing scientific evidence. Most recent reviews estimate a prevalence of one to two cases per 1,000 people for autism, and about six per 1,000 for ASD, with ASD averaging a 4.3:1 male-to-female ratio. The number of people known to have autism has increased dramatically since the 1980s, at least partly as a result of changes in diagnostic practice; the question of whether actual prevalence has increased is unresolved.

Autism causes children to experience the world differently from the way most other children do. It’s hard for people with autism to talk with other people and express themselves using words. Some people who have autism keep to themselves and many can’t communicate without special help.

They also may react to what’s going on around them in unusual ways. Normal sounds may really bother someone with autism — so much so that the person covers his or her ears. Being touched, even in a gentle way, may feel uncomfortable.

Children with autism often can’t make connections that other kids make easily. For example, when someone smiles, you
know the smiling person is happy or being friendly. But a child with autism may have trouble connecting that smile with the person’s happy feelings.

A child who has autism also has trouble linking words with their meanings. Imagine trying to understand what someone is saying if you didn’t know what their words really meant. It is doubly frustrating then if a child can’t come up with the right words to express his or her own thoughts.

Autism causes children to act in unusual ways. They might flap their hands, say certain words over and over, have temper tantrums, or play only with one particular toy. Most kids with autism don’t like changes in routines. They like to stay on a schedule that is always the same. They also may insist that their toys or other objects be arranged a certain way and get upset if these items are moved or disturbed.

If someone has autism, his or her brain has trouble with an important job: making sense of the world. Every day, your brain interprets the sights, sounds, smells, and other sensations that you experience. If your brain couldn’t help you understand these things, you would have trouble functioning, talking, going to work or school, and doing other everyday things. People can be mildly affected by autism, so that they only have a little trouble in life, or they can be very affected, so that they need a lot of help.

Causes:
It has long been presumed that there is a common cause at the genetic, cognitive, and neural levels for autism’s characteristic triad of symptoms. However, there is increasing suspicion that autism is instead a complex disorder whose core aspects have distinct causes that often co-occur.

Autism has a strong genetic basis, although the genetics of autism are complex and it is unclear whether ASD is explained more by multigene interactions or by rare mutations with major effects. Complexity arises due to interactions among multiple genes, the environment, and epigenetic factors which do not change DNA but are heritable and influence gene expression. Early studies of twins estimated heritability explains more than 90% of the risk of autism, assuming a shared environment and no other genetic or medical syndromes. However, most of the mutations that increase autism risk have not been identified. Typically, autism cannot be traced to a Mendelian (single-gene) mutation or to a single chromosome abnormality like Angelman syndrome or fragile X syndrome, and none of the genetic syndromes associated with ASDs has been shown to selectively cause ASD. Numerous candidate genes have been located, with only small effects attributable to any particular gene. The large number of autistic individuals with unaffected family members may result from copy number variations—spontaneous deletions or duplications in genetic material during meiosis. Hence, a substantial fraction of autism cases may be traceable to genetic causes that are highly heritable but not inherited: that is, the mutation that causes the autism is not present in the parental genome.

Gene replacement studies in mice suggest that autistic symptoms are closely related to later developmental steps that depend on activity in synapses and on activity-dependent changes, and that the symptoms may be reversed or reduced by replacing or modulating gene function after birth. All known teratogens (agents that cause birth defects) related to the risk of autism appear to act during the first eight weeks from conception, and though this does not exclude the possibility that autism can be initiated or affected later, it is strong evidence that autism arises very early in development. Although evidence for other environmental causes is anecdotal and has not been confirmed by reliable studies, extensive searches are underway. Environmental factors that have been claimed to contribute to or exacerbate autism, or may be important in future research, include certain foods, infectious disease, heavy metals, solvents, diesel exhaust, PCBs, phthalates and phenols used in plastic products, pesticides, brominated flame retardants, alcohol, smoking, illicit drugs, vaccines, and prenatal stress. Although parents may first become aware of autistic symptoms in their child around the time of a routine vaccination (and parental concern about vaccines has led to a decreasing uptake of childhood immunizations and an increasing likelihood of measles outbreaks), there is overwhelming scientific evidence showing no causal association between the measles-mumps-rubella vaccine and autism, and no scientific evidence that the vaccine preservative thiomersal helps cause autism.

Despite extensive investigation, how autism occurs is not well understood. Its mechanism can be divided into two areas: the pathophysiology of brain structures and processes associated with autism, and the neuropsychological linkages between brain structures and behaviors. The behaviors appear to have multiple pathophysiologies.

Autism affects about 1 in every 150 people, but no one knows what causes it. Some scientists think that some children might be more likely to get autism because it or similar disorders run in their families. Knowing the exact cause of autism is hard because the human brain is very complicated.

The brain contains over 100 billion nerve cells called neurons. Each neuron may have hundreds or thousands of connections to other nerve cells in the brain and body. The connections (which are made by releasing neurotransmitters) let different neurons in different areas of the brain — areas that help you see, feel, move, remember, and much more — work together.

For some reason, some of the cells and connections in the brain of a child with autism — especially those that affect communication, emotions, and senses — don’t develop properly or get damaged. Scientists are still trying to understand how and why this happens.

Symptoms:
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Core symptoms:
The severity of symptoms varies greatly between individuals, but all people with autism have some core symptoms in the areas of:

Social interactions and relationships. Symptoms may include:
*Significant problems developing nonverbal communication skills, such as eye-to-eye gazing, facial expressions, and body posture.

*Failure to establish friendships with children the same age.

*Lack of interest in sharing enjoyment, interests, or achievements with other people.

*Lack of empathy. People with autism may have difficulty understanding another person’s feelings, such as pain or sorrow.

Verbal and nonverbal communication. Symptoms may include:

*Delay in, or lack of, learning to talk. As many as 40% of people with autism never speak.1

*Problems taking steps to start a conversation. Also, people with autism have difficulties continuing a conversation after it has begun.

*Stereotyped and repetitive use of language. People with autism often repeat over and over a phrase they have heard previously (echolalia).

*Difficulty understanding their listener’s perspective. For example, a person with autism may not understand that someone is using humor. They may interpret the communication word for word and fail to catch the implied meaning.

Limited interests in activities or play. Symptoms may include:
*An unusual focus on pieces. Younger children with autism often focus on parts of toys, such as the wheels on a car, rather than playing with the entire toy.

*Preoccupation with certain topics. For example, older children and adults may be fascinated by video games, trading cards, or license plates.

*A need for sameness and routines. For example, a child with autism may always need to eat bread before salad and insist on driving the same route every day to school.

*Stereotyped behaviors. These may include body rocking and hand flapping.

Symptoms during childhood
Symptoms of autism are usually noticed first by parents and other caregivers sometime during the child’s first 3 years. Although autism is present at birth (congenital), signs of the disorder can be difficult to identify or diagnose during infancy. Parents often become concerned when their toddler does not like to be held; does not seem interested in playing certain games, such as peekaboo; and does not begin to talk. Sometimes, a child will start to talk at the same time as other children the same age, then lose his or her language skills. They also may be confused about their child’s hearing abilities. It often seems that a child with autism does not hear, yet at other times, he or she may appear to hear a distant background noise, such as the whistle of a train.

With early and intensive treatment, most children improve their ability to relate to others, communicate, and help themselves as they grow older. Contrary to popular myths about children with autism, very few are completely socially isolated or “live in a world of their own.”

Symptoms during teen years:
During the teen years, the patterns of behavior often change. Many teens gain skills but still lag behind in their ability to relate to and understand others. Puberty and emerging sexuality may be more difficult for teens who have autism than for others this age. Teens are at an increased risk for developing problems related to depression, anxiety, and epilepsy.

Symptoms in adulthood:
Some adults with autism are able to work and live on their own. The degree to which an adult with autism can lead an independent life is related to intelligence and ability to communicate. At least 33% are able to achieve at least partial independence.2

Some adults with autism need a lot of assistance, especially those with low intelligence who are unable to speak. Part- or full-time supervision can be provided by residential treatment programs. At the other end of the spectrum, adults with high-functioning autism are often successful in their professions and able to live independently, although they typically continue to have some difficulties relating to other people. These individuals usually have average to above-average intelligence.

Other symptoms:
Many people with autism have symptoms similar to attention deficit hyperactivity disorder (ADHD). But these symptoms, especially problems with social relationships, are more severe for people with autism. For more information, see the topic Attention Deficit Hyperactivity Disorder.

About 10% of people with autism have some form of savant skills-special limited gifts such as memorizing lists, calculating calendar dates, drawing, or musical ability.1

Many people with autism have unusual sensory perceptions. For example, they may describe a light touch as painful and deep pressure as providing a calming feeling. Others may not feel pain at all. Some people with autism have strong food likes and dislikes and unusual preoccupations.

Sleep problems occur in about 40% to 70% of people with autism.

Other conditions:
Autism is one of several types of pervasive developmental disorders (PDDs), also called autism spectrum disorders (ASD). It is not unusual for autism to be confused with other PDDs, such as Asperger’s disorder or syndrome, or to have overlapping symptoms. A similar condition is called pervasive developmental disorder-NOS (not otherwise specified). PDD-NOS occurs when children display similar behaviors but do not meet the criteria for autism. It is commonly called just PDD. In addition, other conditions with similar symptoms may also have similarities to or occur with autism.

Diagnosis:
Diagnosis is based on behavior, not cause or mechanism. Autism is defined in the DSM-IV-TR as exhibiting at least six symptoms total, including at least two symptoms of qualitative impairment in social interaction, at least one symptom of qualitative impairment in communication, and at least one symptom of restricted and repetitive behavior. Sample symptoms include lack of social or emotional reciprocity, stereotyped and repetitive use of language or idiosyncratic language, and persistent preoccupation with parts of objects. Onset must be prior to age three years, with delays or abnormal functioning in either social interaction, language as used in social communication, or symbolic or imaginative play. The disturbance must not be better accounted for by Rett syndrome or childhood disintegrative disorder. ICD-10 uses essentially the same definition.

Several diagnostic instruments are available. Two are commonly used in autism research: the Autism Diagnostic Interview-Revised (ADI-R) is a semistructured parent interview, and the Autism Diagnostic Observation Schedule (ADOS) uses observation and interaction with the child. The Childhood Autism Rating Scale (CARS) is used widely in clinical environments to assess severity of autism based on observation of children.

A pediatrician commonly performs a preliminary investigation by taking developmental history and physically examining the child. If warranted, diagnosis and evaluations are conducted with help from ASD specialists, observing and assessing cognitive, communication, family, and other factors using standardized tools, and taking into account any associated medical conditions. A pediatric neuropsychologist is often asked to assess behavior and cognitive skills, both to aid diagnosis and to help recommend educational interventions. A differential diagnosis for ASD at this stage might also consider mental retardation, hearing impairment, and a specific language impairment such as Landau-Kleffner syndrome.

Clinical genetics evaluations are often done once ASD is diagnosed, particularly when other symptoms already suggest a genetic cause. Although genetic technology allows clinical geneticists to link an estimated 40% of cases to genetic causes, consensus guidelines in the U.S. and UK are limited to high-resolution chromosome and fragile X testing. A genotype-first model of diagnosis has been proposed, which would routinely assess the genome’s copy number variations. As new genetic tests are developed several ethical, legal, and social issues will emerge. Commercial availability of tests may precede adequate understanding of how to use test results, given the complexity of autism’s genetics. Metabolic and neuroimaging tests are sometimes helpful, but are not routine.

ASD can sometimes be diagnosed by age 14 months, although diagnosis becomes increasingly stable over the first three years of life: for example, a one-year-old who meets diagnostic criteria for ASD is less likely than a three-year-old to continue to do so a few years later. In the UK the National Autism Plan for Children recommends at most 30 weeks from first concern to completed diagnosis and assessment, though few cases are handled that quickly in practice. A 2006 U.S. study found the average age of first evaluation by a qualified professional was 48 months and of formal ASD diagnosis was 61 months, reflecting an average 13-month delay, all far above recommendations.[102] Although the symptoms of autism and ASD begin early in childhood, they are sometimes missed; adults may seek diagnoses to help them or their friends and family understand themselves, to help their employers make adjustments, or in some locations to claim disability living allowances or other benefits.

Underdiagnosis and overdiagnosis are problems in marginal cases, and much of the recent increase in the number of reported ASD cases is likely due to changes in diagnostic practices. The increasing popularity of drug treatment options and the expansion of benefits has given providers incentives to diagnose ASD, resulting in some overdiagnosis of children with uncertain symptoms. Conversely, the cost of screening and diagnosis and the challenge of obtaining payment can inhibit or delay diagnosis. It is particularly hard to diagnose autism among the visually impaired, partly because some of its diagnostic criteria depend on vision, and partly because autistic symptoms overlap with those of common blindness syndromes.

Treatment:
There is no cure for autism, but doctors, therapists, and special teachers can help people with autism overcome or adjust to many difficulties. The earlier a child starts treatment for autism, the better.

The main goals of treatment are to lessen associated deficits and family distress, and to increase quality of life and functional independence. No single treatment is best and treatment is typically tailored to the child’s needs. Intensive, sustained special education programs and behavior therapy early in life can help children acquire self-care, social, and job skills, and often improve functioning and decrease symptom severity and maladaptive behaviors; claims that intervention by age two to three years is crucial are not substantiated. Available approaches include applied behavior analysis (ABA), developmental models, structured teaching, speech and language therapy, social skills therapy, and occupational therapy.Educational interventions have some effectiveness in children: intensive ABA treatment has demonstrated effectiveness in enhancing global functioning in preschool children and is well-established for improving intellectual performance of young children.[106] Neuropsychological reports are often poorly communicated to educators, resulting in a gap between what a report recommends and what education is provided. The limited research on the effectiveness of adult residential programs shows mixed results.

Many medications are used to treat ASD symptoms that interfere with integrating a child into home or school when behavioral treatment fails. More than half of U.S. children diagnosed with ASD are prescribed psychoactive drugs or anticonvulsants, with the most common drug classes being antidepressants, stimulants, and antipsychotics. Aside from antipsychotics, there is scant reliable research about the effectiveness or safety of drug treatments for adolescents and adults with ASD. A person with ASD may respond atypically to medications, the medications can have adverse effects, and no known medication relieves autism’s core symptoms of social and communication impairments.

Although many alternative therapies and interventions are available, few are supported by scientific studies.Treatment approaches have little empirical support in quality-of-life contexts, and many programs focus on success measures that lack predictive validity and real-world relevance. Scientific evidence appears to matter less to service providers than program marketing, training availability, and parent requests. Though most alternative treatments, such as melatonin, have only mild adverse effects some may place the child at risk. A 2008 study found that compared to their peers, autistic boys have significantly thinner bones if on casein-free diets; in 2005, botched chelation therapy killed a five-year-old child with autism.

Treatment is expensive; indirect costs are more so. A U.S. study estimated an average cost of $3.2 million in 2003 U.S. dollars for someone born in 2000, with about 10% medical care, 30% extra education and other care, and 60% lost economic productivity. Publicly supported programs are often inadequate or inappropriate for a given child, and unreimbursed out-of-pocket medical or therapy expenses are associated with likelihood of family financial problems; one 2008 U.S. study found a 14% average loss of annual income in families of children with ASD, and a related study found that ASD is associated with higher probability that child care problems will greatly affect parental employment. After childhood, key treatment issues include residential care, job training and placement, sexuality, social skills, and estate planning.

Different children need different kinds of help, but learning how to communicate is always an important first step. Spoken language can be hard for kids with autism to learn. Most understand words better by seeing them, so therapists teach them how to communicate by pointing or using pictures or sign language. That makes learning other things easier, and eventually, many children with autism learn to talk fluently.

Therapists also help children learn social skills, such as how to greet people, wait for a turn, and follow directions. Some children need special help with living skills (like brushing teeth or making a bed). Others have trouble sitting still or controlling their tempers and need therapy to help them control their behavior. Some children take medications to help their moods and behaviour, but there’s no medicine for autism.

Students with mild autism sometimes can go to mainstream school. But many children with autism need calmer, more orderly surroundings. They also need teachers trained to understand the problems they have with communicating and learning. They may learn at home or in classes at special or private schools.

Click to see:->
Gut and Psychology Syndrome: Natural Treatment for Autism
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Autism – Natural Remedies formulated by a Clinical Psychologist

Natural & Herbal Remedies for Autism

Chelation of Mercury for the Treatment of Autism

Native Remedies of Autism

Natural Therapy of Autism

Other conditions
Autism is one of several types of pervasive developmental disorders (PDDs), also called autism spectrum disorders (ASD). It is not unusual for autism to be confused with other PDDs, such as Asperger’s disorder or syndrome, or to have overlapping symptoms. A similar condition is called pervasive developmental disorder-NOS (not otherwise specified). PDD-NOS occurs when children display similar behaviors but do not meet the criteria for autism. It is commonly called just PDD. In addition, other conditions with similar symptoms may also have similarities to or occur with autism.

Prognosis:
There is no known cure. Children recover occasionally, sometimes after intensive treatment and sometimes not; it is not known how often this happens. Most children with autism lack social support, meaningful relationships, future employment opportunities or self-determination. Although core difficulties remain, symptoms often become less severe in later childhood. Few high-quality studies address long-term prognosis. Some adults show modest improvement in communication skills, but a few decline; no study has focused on autism after midlife. Acquiring language before age six, having an IQ above 50, and having a marketable skill all predict better outcomes; independent living is unlikely with severe autism. A 2004 British study of 68 adults who were diagnosed before 1980 as autistic children with IQ above 50 found that 12% achieved a high level of independence as adults, 10% had some friends and were generally in work but required some support, 19% had some independence but were generally living at home and needed considerable support and supervision in daily living, 46% needed specialist residential provision from facilities specializing in ASD with a high level of support and very limited autonomy, and 12% needed high-level hospital care. A 2005 Swedish study of 78 adults that did not exclude low IQ found worse prognosis; for example, only 4% achieved independence. A 2008 Canadian study of 48 young adults diagnosed with ASD as preschoolers found outcomes ranging through poor (46%), fair (32%), good (17%), and very good (4%); 56% of these young adults had been employed at some point during their lives, mostly in volunteer, sheltered or part time work. Changes in diagnostic practice and increased availability of effective early intervention make it unclear whether these findings can be generalized to recently diagnosed children.

Living With Autism:
Some children with mild autism will grow up and be able to live on their own. Those with more serious problems will always need some kind of help. But all children with autism have brighter futures when they have the support and understanding of doctors, teachers, caregivers, parents, brothers, sisters, and friends.

Disclaimer: This information is not meant to be a substitute for professional medical advise or help. It is always best to consult with a Physician about serious health concerns. This information is in no way intended to diagnose or prescribe remedies.This is purely for educational purpose.

Resources:
http://www.charliebrewersworld.com/page4.htm
http://en.wikipedia.org/wiki/Autism
http://www.webmd.com/brain/autism/autism-symptoms

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Faulty Gene Causes Heart Attack Death

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A faulty gene variant that can cause heart attack mortalities also potentially opens the way for improved treatment following such attacks.
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“It’s been known for some time that a defective ACE2 gene is associated with high blood pressure, but our research has also clearly linked one variant of this gene to a greater likelihood of mortality after heart attack,” said lead researcher Barry Palmer of Otago University, Christchurch.

“This is particularly in middle aged males who have acute coronary syndromes, or reduced flow of blood to the heart,” he added.

Otago scientists carried out the study over three years on a large cohort of 1,075 people (males and females) recruited from hospitals. They found, after adjusting for variables such as age, that male patients are almost twice as likely to die if they had one particular (defective) variant of the ACE2 gene.

“This is the first time ever that this variant of the ACE2 gene has been identified in terms of survivability,” said Palmer. “It will be useful in terms of other research we’re doing on tailoring heart disease treatment more accurately to the patient.”

“If we can identify those people at greater risk we may be able to do more earlier on in their treatment, and it’s easy enough to identify if someone has this variant of the gene.”

Males are more prone than females to the effects of the ACE2 gene variant which is linked to reduced survival because of their chromosomal make-up. That’s because males have only one copy in each cell of the ACE2 gene on the X chromosome and none on the Y chromosome, whereas females have two X chromosomes, according to an Otago release.

This means that if a male has a defective ACE2 gene variant there is no complementary chromosome which can compensate for that ineffective gene. Females have an alternative copy of the gene on their second X chromosome which can compensate for the defective ACE2 gene, and provide normal blood pressure to the heart.

In its normal form on the X chromosome the ACE2 gene produces an enzyme which controls blood pressure by influencing hormone levels. It is only when that gene is defective that blood pressure may increase.

The research was published in the October issue of the American Heart Journal.

You may click to see:->FAMILIAL HYPERCHOLESTEROLAEMIA Cardiovascular disease

Sources:
The Times Of India

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How Contraceptive Pill Influences Partner Choice

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The contraceptive pill may disrupt women’s natural ability to choose a partner genetically dissimilar to themselves. This could result in difficulties when trying to conceive, an increased risk of miscarriage and long intervals between pregnancies. Passing on a lack of diverse genes to children could also weaken their immune systems.

Humans tend to be attracted to those with a dissimilar genetic make-up to themselves, maintaining genetic diversity, which is signaled by subtle odors. A research team analyzed how the contraceptive pill affects odor preferences, and found that the preferences of women who began using the contraceptive pill shifted towards men with genetically similar odors.

Not only could genetic similarity in couples lead to fertility problems, but it could ultimately lead to the breakdown of relationships when women stop using the contraceptive pill, as odor perception plays a significant role in maintaining attraction to partners, researchers said.
Sources:
Eurekalert August 12, 2008
Proceedings of the Royal Society B: Biological Sciences August 12, 2008

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Talk About Genes

Diagram of the location of introns and exons w...Image via Wikipedia

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People who are sick look at those who are well and wonder: Why am I ill? Why not them? Is it the environmental pollution? Or my diet? Perhaps it is the witches, curses or the evil eye. Maybe incantations and amulets will set things right.

Human genes are located on 23 pairs of chromosomes

Today, rapid scientific advance in microbiology has helped identify disease-causing organisms (bacteria and viruses) not visible to the naked eye. Biochemistry has helped locate the exact molecular level at which enzyme reactions become faulty and result in diseases. We also know now that most diseases have a genetic basis. People may have the same genotype or genetic configuration, but the expression of these genes in the body (the phenotype) may be different. This makes one’s response to disease different from another’s — some succumb to it while others don’t.

Genes are located on specific loci on chromosomes. We inherit 20,000-30,000 genes, located on 23 pairs of chromosomes, from our parents. Twenty-two of these are identical. The 23rd is the sex chromosome. If it is expressed as XX, the person is a female and if it is XY, the person is a male.

Abnormal genes that theoretically should cause disease can vary in their penetrability. A person may carry the gene and yet not express the disease. But he or she will, however, pass it to his or her children. The disease may suddenly manifest itself generations later, puzzling everyone as to why no one in the family has it. This is true of vitiligo (white patches), icthyosis (dry skin), psoriasis and other conditions.

A single defective gene can produce abnormalities in multiple organs. The gene causing osteogenesis imperfecta (where the fragile bones keep breaking) also causes deafness and defective teeth. Some gene positive individuals may have normal bones, but their joints may be abnormally mobile and hyper extensible. They are often advertised in circus acts as “rubber or plastic people”.

A defective gene may be dominant — that is, it expresses itself in all the people who carry it. Or it may be recessive and a person expresses the disease only if he or she has inadvertently been saddled with two defective genes, one from each parent. This is most likely to occur in communities where consanguinity (marrying a relative like a cousin or an uncle) is prevalent. This accounts for diseases like sickle cell disease and thalassaemia.

Some traits are X-linked and carried on the X chromosome. Females are protected as they have two copies of the X, one from the mother and the other from the father. Males get their X from their mother and their Y from their father. Unprotected by a normal chromosome, they express any disease caused by a defective X from the mother. Muscular dystrophy and haemophilia are X-linked diseases carried by apparently normal women and passed on to their sons.

Sex limited inheritance may be expressed only in one sex even if the inheritance is dominant. A typical example is premature baldness. Men are more likely to be bald even though women, too, may carry the gene. Women are protected until menopause by the female hormones. Sometimes an abnormality occurs in a child despite the parents being genetically normal. This occurs because of spontaneous changes or mutations during early embryonic development, with an injury — like a viral infection, medications or radiation — causing the changes. Eighty per cent of “circus dwarfs” fall in this category.

As cells age, the proteins comprising genes become faulty. The chromosomes themselves may develop deletions, translocations and abnormal attachments. Parents may then give birth to children with diseases like Down’s Syndrome.

Many diseases like high blood pressure, diabetes, heart disease and cancer have a “multifactorial inheritance”. Although the defective genes have been inherited, the disease manifests itself only when there is the required mix of environmental and genetic factors. Alcoholism and drug abuse are hereditary, but will not manifest themselves in a regimentalised, teetotal society where neither alcohol nor drugs is available.

Genes, chromosomes and their inheritance can be plotted and studied. Genetic screening can identify people at risk for a particular disorder. Testing is appropriate even before symptoms begin if there is a strong family history of the disorder. In the case of sickle cell anaemia, thalassaemia and breast cancer, it may help to identify asymptomatic people and may be life saving. Tests can be done for some diseases before birth (in utero) with maternal blood samples, chorionic villous sampling, or amniotic fluid or umbilical cord blood. Neonates with inborn errors of metabolism (IEM) can be diagnosed a few hours after birth. At this time it may be possible to initiate life-saving treatment.

Gene therapy is being studied. It involves the insertion of copies of normal genes, switching off faulty genes or stem cell transplantation and therapy. Science is progressing by leaps and bounds. Perhaps the day is not far when genetic diseases, too, will be a part of the past.

Sources: The Telegraph (Kolkata, India)

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Decoding Diseases

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The 1000 Genome Project promises to provide genetic clues to all the major ailments plaguing humankind.

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For a long time in the history of science, scientists had relied on tact and finesse in their investigations into Nature. They designed ingenious experiments and constructed exquisite theories to probe into Nature’s patterns. But some of them are now combining finesse with brute force, and in the process uncovering some of Nature’s most profound mysteries.

At the Wellcome Trust Sanger Institute in Cambridge in the United Kingdom, biologists are using brute force like never before in the history of biology. They are sequencing genomes (the full complement of genes in a person) at breakneck speed: about 300 million bases of DNA an hour, seven billion a day, 50 billion a week. In the last six months, scientists there have sequenced more than one trillion letters of genetic code. That is the equivalent of 300 human genomes. Every two minutes, the institute generates as much sequence as was done in the first five years of genome mapping (from 1982-1987).

While sequencing at such a speed, which will itself keep going up each year, biologists are getting closer to answering some critical questions. At a fundamental and philosophical level, it will tell us why we are all so similar and yet so different. At a more practical level, it will tell us why some of us get sick while others don’t. Or to be precise, we will soon know how genetic variation contributes to disease. Says Richard Durbin, co-leader of the three-year 1000 Genome Project that the Institute launched with two other institutions: “At the end of the project, we will have a much clearer picture of what the human genome really looks like.”

The first draft of the human genome, produced by US and UK scientists in 2000, was a major breakthrough in biology. However, there were many gaps in the draft that have still not been plugged. It turns out that the gaps contain the crucial data that we need to understand health and disease. Moreover, the draft was based only on primary data. It is the secondary data, the variations in the reference sequence, which will tell us about risk factors for diseases. That is what biologists are after now.

The 1000 Genome Project was launched in January this year with the aim of producing a map of the human genome that is medically relevant. There are three institutions in the project: the Wellcome Trust Sanger Institute, the Beijing Genomics Institute at Shenzen in China, and the National Human Genome Research Institute at Bethesda, Maryland, in the US. Later, three US based companies — 454 Life Sciences, Illumina and Applied Biosystems — joined the project by providing sequencing equipment. This sequencing equipment has been developed recently and has not been tested in actual research. It has provided what biologists there call the next generation sequencing technology.

The power of this technology was unimaginable even two years ago. At that time the institute had 75 machines and could sequence 50 billion bases a year. Now it has 25 machines and can sequence 50 billion bases a week. “We had a major shift in technology last year,” says Harold Swerdlow, head of sequencing technology at the Wellcome Trust Sanger Institute. “The speed of sequencing has gone up 100 times and the cost has gone down by 100 times.”

Without this improvement in technology, the 1000 Genome Project may not have been possible or would have taken too long. As the plans stand now, the first year is for a pilot project. It will do two things: learning to work with the technology, and test the technology itself. Scientists in the project are now sequencing the DNA of 180 people in three equal sets of 60: people of European origin (the sample came from Utah in the US), Africans (sample from Nigeria) and East Asians (sample from China and Japan). The sequencing is at a low depth, a term biologists use to denote the number of times they sequence a gene and thus its accuracy. By the end of the project, they would have sequenced 1000 genomes at an accuracy unavailable so far. They would have had to sequence a genome at least about 40 times to reach this stage.

Maps of genetic variation that exist now are called HapMap. The scientists already have about 130 places of genetic variation that can increase the risk of diabetes, breast cancer, arthritis, inflammatory bowel disease and so on. However, this map identifies variations at a frequency of 5 per cent or more. The 1000 Genome Project will identify gene variations at a frequency of 1 per cent or even less. It will then open up possibilities of developing markers and treatment for a large number of diseases. Says Sameer Brahmachari, a biologist and director general of the Council of Scientific and Industrial Research, New Delhi: “If the physical traits of the sequenced individuals are studied and correlated with their genome, the 1000 genome sequence can be an invaluable resource.”

Sources: The Telegraph (Kolkata, India)

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