ells remains 46, the presence of an extra part of the number 21 chromosome causes the features of Down syndrome. As with nondisjunction trisomy 21, translocation occurs either prior to or at conception. Unlike nondisjunction, maternal age is not linked to the risk of translocation. Most cases are sporadic, chance events. However, in about one-third of cases, one parent is a carrier of a translocated chromosome. For this reason, the risk of recurrence for translocation is higher than that of nondisjunction. The diagnosis of Down syndrome is usually suspected after birth as a result of the baby's appearance. There are many physical characteristics that form the basis for suspecting an infant has Down syndrome. Many of these characteristics are found in normal, healthy children who do not have Down syndrome. If the slightest traces of Down syndrome are suspected, a karyotype will be performed to obtain the diagnosis. Some infants with Down syndrome have only a few of these traits, while others have many. Doctors' look for traits like low muscle tone, flat facial profile, a somewhat depressed nasal bridge, a small nose, an upward slant to the eyes, an abnormal shape of the ear, a single deep crease across the center of the palm, an excessive ability to extend the joints, small skin folds on the inner corner of the eyes, excessive space between large and second toe, and an enlargement of tongue in relationship to size of mouth. Once a child is diagnosed with Down syndrome he or she is extremely exposed to many health related problems. Congenital heart defects, increased susceptibility to infection, respiratory problems, obstructed digestive tracts and childhood leukemia occur with greater frequency among children who have Down syndrome. However, advances in medicine have made it possible for most of these health problems treatable. In 1910, children with Down syndrome were expected to survive to age 9. With the discovery of...
