By Alan Harchik, Ph.D., BCBA
causes developmental disabilities in children? This is a question
parents and professionals often ask. Some disabilities appear to
be due to chromosome or gene disorders. Learning more about these
types of disorders may lead to better prevention, and can help couples
make decisions when they are planning to start a family.
and genes are in every cell of our body. In every cell, we have
46 chromosomes that occur in 23 pairs. One of each pair came from
each of our parents. Chromosomes contain genes that instruct our
body to grow, develop, and function. It is estimated that there
are more than 20,000 genes in every cell.
part of a chromosome is missing or duplicated. Other times, parts
of the chromosome stick together or get rearranged in the wrong
order. As a result, genes are missing, altered, or deformed. This
may result in a medical condition or a learning problem. Sometimes
there is no obvious impairment.
are conducting more and more chromosomal and genetic research to
(1) identify the chromosome and gene irregularities that occur in
children with specific disabilities, (2) explore what causes the
irregularities, and (3) examine best treatments for these children.
Disorders and Their Causes
Researchers have identified specific chromosome or genetic problems
for a number of developmental and cognitive disabilities. At May
Institute, we support individuals with these disabilities in our
programs here in western Massachusetts.
Down syndrome occurs when the cells contain an extra chromosome.
The extra chromosome causes delays in development, mild to moderate
mental retardation, and specific physical characteristics. Approximately
one in 800 newborns is diagnosed with Down syndrome.
Fragile X syndrome is a hereditary deformity of a specific gene
FMR1) on the X chromosome. This usually results in mild mental retardation,
language delays, behavioral problems, and/or autistic-like behavior.
It occurs once in approximately every 5,000 newborns.
Rett syndrome, a disorder on the autism spectrum, includes mental
retardation, loss of motor ability, and/or purposeless wringing
Recently, a specific gene MECP2 located on the X chromosome,
was identified in children with this syndrome. Rett occurs in fewer
than one in 10,000 births.
specific chromosome or gene abnormalities is a first step in learning
more about these disabilities. Unfortunately, we still know very
little about what causes these genetic disturbances. Some are passed
down from parent to child, others might be random occurrences, and
still others may be due to environmental factors.
The cause of autism may turn out to be a combination of genetic
and environmental factors. Currently, no specific genes or environmental
factors have been identified. There continues to be a lot of speculation
in the public about things that could cause autism, such as pollutants,
viruses, and vaccines. Research findings, however, remain unconvincing
of the causes of developmental disabilities may help prevent future
occurrences, but there are thousands of children and adults who
need education and therapy today. We know that individuals with
these disabilities can learn, grow, and lead high-quality lives.
How can we support them? First, each persons needs should
be assessed to determine goals. Then, best practices (those with
evidence showing their effectiveness) should be used. These include
teaching in small steps, providing rewards, and guiding correct
performance. Second, related medical conditions should be monitored
and the potential positive role of medications should be considered.
Third, support groups for individuals as well as families are available
and are useful. Finally, many families may find genetic counseling
to be valuable.
Institute operates schools for children and adolescents with autism
and other developmental disabilities in Arlington, Braintree, Chatham,
and West Springfield, Mass., and in Freeport, Maine. We also provide
residential and day services for adults. For more information, contact
us at 800-778-7601, or at www.mayinstitute.org.