Conditions Associated With Webbed Hands & Feet

Down Syndrome

Under normal circumstances, humans are born with two copies of each chromosome. In Down syndrome, also known as trisomy 21, the patient has either part or all of a third copy of chromosome 21. Trisomy 21 is a common chromosomal disorder that affects about one of every seven hundred babies, and it is most likely to occur if the mother is over thirty-five years old during her pregnancy.

Patients with trisomy 21 grow more slowly than normal children. Consequently, they are shorter than average; the typical man with trisomy 21 typically stands no more than five feet one inch tall. The vast majority of patients have at least some degree of intellectual disability; most have an IQ of about fifty, which means their intelligence matches that of an average eight- or nine-year-old child. Other common characteristics include poor muscle tone, eyes that slant upward, a flat nasal bridge, a large protruding tongue, and a single deep crease in the middle of the palm.

About fifty percent of Down syndrome patients are also born with a heart defect and are also more likely to develop epilepsy and leukemia than the general population. Adults with trisomy 21 are more susceptible to dementias like Alzheimer's. The current life expectancy of a patient with Down syndrome is around sixty years.