Autism and genetics
Autism is a developmental disorder characterized by a range of challenges with social interaction, communication, and repetitive behaviors. Research indicates that genetics play a significant role in the likelihood of developing autism, with boys being nearly five times more likely to be diagnosed than girls. The risk of autism is notably higher in siblings of affected children, highlighting the genetic component. Various genetic markers and conditions, such as fragile X syndrome and neurofibromatosis, have been associated with autism, suggesting a complex interplay of multiple genes influencing its development.
The expression of autism is influenced by genetic, developmental, and environmental factors, making it a highly individualized condition. Symptoms typically emerge before the age of three and can vary widely in severity, with some children displaying exceptional abilities alongside their challenges. While there is currently no cure for autism, early intervention and supportive therapies can greatly enhance the quality of life for individuals with the condition. As research continues to explore the genetic underpinnings of autism, awareness and understanding remain vital for families and communities.
Autism and genetics
Also known as: Autism spectrum disorder (ASD), Pervasive development disorder (PDD)
DefinitionAutism represents a spectrum of complex brain disorders resulting in social, behavioral, and language problems. People with autism have difficulty communicating and forming relationships. They may be preoccupied, engage in repetitive behaviors, and exhibit marked inflexibility. Autism occurs in about one in sixty-eight children, according to the Centers for Disease Control and Prevention (CDC).
Risk Factors
Boys are nearly five times more likely than girls to have autism. Siblings of a child with autism have nearly a 20-percent chance of being autistic.
A number of other conditions are associated with autism, although the relationships among them are not clear. These conditions include neurofibromatosis, tuberous sclerosis, fragile X syndrome, phenylketonuria (PKU), Möbius syndrome, epilepsy, herpes encephalitis, and cytomegalovirus. The speech disorder apraxia, a rare disorder in non-autistic children, has a 65 percent chance of occurring in autistic children.
Children born to women who have problems during pregnancy or delivery, or who contract rubella during pregnancy, are also at risk. These conditions primarily affect the central nervous system.
Etiology and Genetics
Autism is a complex condition whose expression is determined by a host of genetic, developmental, and environmental factors. While the genetic determinants appear to play the predominant role, they are difficult to quantify since so many different genes are apparently involved.
The first genetic region shown to have an association with autism is a deoxyribonucleic acid (DNA) sequence on chromosome 5 that is between two genes that specify cell-adhesion molecules. These proteins are important components of nerve synapses, the junctions between nerve cells. In subsequent years, many additional genes or genetic regions have been implicated in autism occurring in some families. A 2019 report identifies no fewer than forty different genetic regions with rare copy number variations (duplications or deletions), located on twenty different chromosomes, that were found in children with autism but not in the control group. Specific genes that are thought to play a contributing role in some cases include Shank3 (at position 22q13.3), BZRAP1 (at position 17q23.2), MDGA2 (at position 14q21), MECP (at position Xq28), and PTEN (at position 10q23.31).
One classical estimate of the extent to which genetics plays a role in the development of a complex trait or disease is the measurement of concordance rates in monozygotic (identical) twins as compared with those for dizygotic (fraternal) twins. Such measurements for autism have been reported as 70 percent in monozygotic twins and 5 percent in dizygotic twins, confirming the importance of genetic factors in the etiology of the disease.
Symptoms
Autism first appears in children aged three and younger. The severity of symptoms varies over a wide spectrum. Behaviors and abilities may differ from day to day; symptoms may decrease as the child grows older. Children with autism may exhibit a combination of abnormal behaviors.
Symptoms include avoiding social contact, loss of language, using words incorrectly, changing the meaning of a common word, gesturing frequently, avoiding eye contact, and having trouble with nonverbal communication. Other symptoms include lack of interest in normal activities for their age; spending a lot of time alone; not playing imaginatively; not starting pretend games; not imitating others; sensitivity to sound, smell, taste, sights, and touch; responding to stimulation in an abnormal way; and not reacting to smiles in the manner expected. Hyperactivity; passiveness; tantrums; single-mindedness; aggression; hurting themselves or self-mutilation; repetitive movements, such as rocking or flapping a hand; resisting change; forming odd attachments to objects; sniffing or licking toys; and not understanding other people’s feelings and needs are additional symptoms.
Some people with autism suffer from other disorders as well, including seizures, intellectual disabilities, and genetic disorders, such as fragile X syndrome.
Some people with autism have unusual abilities. For example, they may memorize things or be able to play a musical instrument without lessons. Children with autism may show varying signs of cognitive impairment but have normal intelligence. According to the Autism Information Center, children with autism may be very good at putting puzzles together or solving problems, but instead have trouble in other areas, like talking or making friends. Autism, a group of developmental disabilities caused by abnormality in the brain, is a highly individualized disorder.
Screening and Diagnosis
Doctors who specialize in autism will observe a child’s behavior, social contacts, and communication abilities. They will assess mental and social development and ask parents about the child’s behavior. Different methods of screening and testing may be required for diagnosis, but the process follows two general steps: developmental screening and comprehensive diagnostic evaluation. The first step includes short tests before the age of three to determine if a child has any developmental delays, while the second includes more in-depth testing.
Tests may include neuropsychological tests, questionnaires and observation schedules, and intelligence quotient (IQ) tests. Medical tests can rule out other conditions that cause similar symptoms. Blood tests, urine tests, genetic testing, and electroencephalograms (EEG) are among these medical tests.
Treatment and Therapy
There is no cure for autism. The severity of symptoms may decrease over the years, but the condition lasts for life. Children with autism and their families may benefit from early intervention. Children with autism respond well to a structured, predictable schedule. With help, many children with autism learn to cope with their disabilities. Most need assistance and support throughout their lives. Others are able to work and live independently when they grow up.
Interventions to help children with autism include special education programs; these programs are designed to meet the child’s special needs and improve the odds of learning. Children with autism may have trouble with assignments, concentration, and anxiety. Teachers who understand the condition can build on the child’s unique abilities. Programs should incorporate the child’s interests. Some children do better in a small-group setting; others do well in regular classrooms with special support. Vocational training can help prepare young adults for jobs.
Therapy services, such as speech, physical, and occupational therapies, may improve speech and activities. Children with autism need help developing social skills.
Professional support helps a family cope with caring for a child with autism. Counselors help parents learn how to manage behaviors. Caring for a child with autism can be exhausting and frustrating; arranging occasional respite care is essential, so that the main caregiver can have some breaks.
Although there are no drugs to treat autism, several drugs are used to help manage symptoms. For example, drugs prescribed for anxiety and depression can help tone down obsessive and aggressive behaviors.
Prevention and Outcomes
There are no guidelines for preventing autism because the cause is unknown. Scientists are actively searching for its underlying causes.
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