Down syndrome
Down syndrome is
usually diagnosed at birth on the basis of the
typical facial features, hypotonia, and single
palmar crease. Down syndrome is the most common chromosomal
disorder. An estimated 1 in 800 infants are born
with Down syndrome. Down syndrome is also a common
cause of miscarriage. Down syndrome is a genetic disorder that results
in varying degrees of physical and mental
retardation. The condition varies in severity,
causing developmental problems that range from mild
to severe. The disorder occurs as a result of extra
genetic material.
Risk factors
Many pregnancies
carrying a fetus with Down syndrome can be detected in the early second
trimester trough screening maternal serum for alpha - fetoprotein
and certain hormones ("triple screen") and by detecting increased nuchal
thickness on fetal ultrasound. Woman's chances of
giving birth to a child with Down syndrome increase with age. Because a
woman's eggs age, there's a greater inclination for chromosomes to
divide improperly. At 35 the chance a woman will have a child with Down
syndrome is one in 400. At 40, it's one in 105. By age 49, the risk of
having a child with Down syndrome jumps to one in 12.
With more women
delaying childbearing, doctors continue to be concerned about an
increasing incidence of Down syndrome.
Typically, a
mother who has one child with Down syndrome has about a one in 100
chance of having another child with Down syndrome.
