March 5, 2007 10:32pm CST
It is a congenital disorder, caused by the presence of an extra 21st chromosome, in which the affected person has mild to moderate mental retardation, short stature, and a flattened facial profile. The most common type (trisomy 21) is due to a nondisjunction of chromosome 21 during the original cell division, resulting in an extra chromosome 21. These children have a total of 47 chromosomes instead of the usual 46. However, the extra material from chromosome 21 can also be attached to another chromosome through translocation; such children have Down syndrome but only 46 chromosomes. More rarely, the trisomy 21 breaks up, giving some cells with 47 chromosomes and some with 46 (mosaicism). The characteristic physical features include almond-shaped eyes; a rounded, brachycephalic skull with flattened occipital region; a broad, flattened bridge of the nose; an enlarged fissured tongue; broad hands with stubby fingers; often a single “simian” palmar crease; hypotonic muscle development; thick, everted, and cracked lips; dry, rough skin; subnormal height; and infantile genitalia. Not all of these physical signs are present in every case, and some may be observed in individuals without Down syndrome. However, Down syndrome is diagnosed when most of the anomalies are present. I have 2 daughters and the younger is like this. But she gives us a lot of joy and I love her very much.