Down\'s Syndrome


Down\'s syndrome is a genetic condition involving an extra chromosome,
this change occurs around the time of conception. A person with Down\'s syndrome
has forty-seven chromosomes instead of the usual forty-six. A relatively
common genetic disorder, Down\'s strikes 1 out of 600 babies. In 95 percent of
all cases, the disorder originates with the egg, not the sperm, and the only
known risk factor is advanced maternal age-at age 35, a woman has 1 chance in
117 of having a baby with Down\'s; at 40, her odds are 1 in 34. (Graves, 1990)

People with Down\'s syndrome all have a certain degree of learning
disability . This means that they develop and learn more slowly than other
children. However, most children with Down\'s syndrome today will walk and talk,
many will read and write, go to ordinary school, and look forward to a semi-
independent adult life. (Platt and Carlson, 1992)

Facts on Down Syndrome

*Down syndrome is not a lethal anomaly. One to two percent of persons
born with this disorder have uncorrectable heart defects at birth. The average
life expectancy for all others is now beyond age 55 years.
*Today less than 5% of persons with Down syndrome have severe-to-
profound mental retardation. The majority are on the border of mild-to-moderate
mental retardation, and some are exhibiting normal IQ scores today.
*The average reading level for persons with Down syndrome is 3rd grade,
with many reading at 6th-12th grade levels today.
*The vast majority of adults with Down syndrome today can be expected to
live semi- or totally independently and many enter the work force with today\'s
supported employment programs and some are competitively employed.

Some medical conditions that demand special attention for people with
Down syndrome include:

*Congenital Heart Disease: usually in the form of endocardial cushion
defects, affects 40% of babies and should be screened for by echocardiography
soon after birth as it may well be difficult to detect.
* Gastrointestinal disorders: the most common congenital abnormality of
the gastrointestinal tract associated with Down syndrome is duodenal atresia,
although pyloric stenosis, Hirschsprung\'s disease and tracheo-oesophageal
fistulae have all been reported.
* Vision: Three percent of newborns with Down syndrome will have dense
congenital cataracts which should be removed early. Glaucoma is also common.
* Congenital Hypothyroidism: This condition is slightly more prevalent
in babies with Down syndrome. It should be detected by the routine heelprick
screen performed on all babies.
*Congenital dislocation of the hips: Joint laxity and hypotonia can
combine to increase the incidence of hip dislocation, although true congenital
dislocation is quite rare.
* Sensory deficits: Significant hearing impairments occur in the
majority of children with Down syndrome. Annual audiometry and specialist
consultation is recommended.
* Atlantoaxial instability: Up to 15% of children with Down syndrome
will have evidence of instability of the atlantoaxial joint but in only a
handful of cases will this instability result in an impingement on the spinal
cord with resultant neurological signs.
* Physical growth: Physical development is invariably delayed in
children with Down syndrome. A tendency towards obesity requires special
attention to healthy diet and exercise habits in this group.
* Dental care: The teeth of children with Down syndrome tend to be small,
irregularly spaced and misshapen. Early and frequent dental care is required to
ensure adequate dentition for adult life.
* Psychiatric disorders: Psychiatric illnesses occur in people with Down
syndrome with much the same frequency as in the rest of the population.
*Dementia: Much recent attention has been focused on the association
between Down syndrome and Alzheimer\'s disease. There appears to be a gene-dose
effect where having an extra chromosome 21 gives an individual a higher chance
of developing Alzheimer\'s disease. (Newton, 1992)

A significant amount of research has been conducted on Down syndrome, in
particular many methods to detect Down syndrome in fetuses have been developed.
This is a controversial issue for researchers and for families who have Down
syndrome children and adults. The following is a discussion of some of the
detection methods for Down syndrome, and the facilities in which they were
developed.

Jones Institute

Scientists at Norfolk\'s Jones Institute for Reproductive Medicine say
they have overcome most technical hurdles to screening embryos for Down syndrome
and many other chromosomal defects before the embryos are implanted in a woman\'s
uterus.
The institute, part of Eastern Virginia Medical School, hopes to try out
the technique with a handful of high-risk couples who come to the institute for
in-vitro fertilization, in the near future. (www #1)
Eventually, all couples who go through the Jones Institute may have the
option to screen for Down and most of the other conditions caused by an extra
chromosome on one of 23 pairs that make