Down syndrome is a genetic disease that affects about one person per every 733 births. This condition is very rare, but it is much more frequent among people who are born by older parents. For example, if a maternal age is 20 to 24, the probability is one in 1562. At the age of 35 women will have one in 214 chances of conceiving a baby with Down syndrome, while much older mothers, above 45, have even more risk of delivering baby with this condition: one in every 19 births.
Parental age is an important factor because of increased mutagenic exposures upon some older parents' reproductive cells. Down syndrome develops as a chromosomal abnormality that happens with an error in cell division. When this chromosomal abnormality results in an extra copy of chromosome 21, a child is born with Down syndrome.
Down syndrome palms
One of the most common features seen in people suffering from Down syndrome is a typical appearance of their palms. In most cases, people with Down syndrome will have a single transverse palmar crease. This appears as a single crease that stretches across the palm of the hand. It is actually formed by fusion of two palmar creases, which are normally seen on a human hand.
This feature is commonly seen among the non-human higher primates – simians, usually among the monkeys. Therefore, it is also referred to as a simian crease or simian line. According to scientific information, men are twice likely as females to have this feature. People with Down syndrome usually have atypical fingerprints in about 90 percent of all cases. Single transverse palmar crease is also very frequent sign of this disease, but it is actually seen in only about 45 percent of patients.
A single transverse palmar crease is also used as one of the most valuable diagnostic clues. A look at the infant’s hand can reveal certain abnormalities in palm lines and fingertip patterns, which may signal presence of some serious health problems. For example, this may give a clue to pediatricians to the existence of congenital heart defects, and other chromosomal disorders.
A single transverse palmar crease is also seen among children who suffer from a fetal alcohol syndrome, or cri du chat syndrome. Cri du chat syndrome is also a genetic disorder that occurs when the part of chromosome 5 is missing.
Bilateral or unilateral single palmar creases are associated with many chromosomal conditions such as aberrations on chromosome 9, Klinefelter syndrome, Noonan syndrome, Patau syndrome, Edward's syndrome, and Aarskog-Scott syndrome.