In a case where a fetus is diagnosed with Patau's
Syndrome, do both parents have to have the genetic gene? Would you also
give me more information on this syndrome?
Patau's is very rare. It is caused by a trisomy, or nondisjunction of the
13th chromosome pair. This happens during the formation of eggs or sperm.
Normally each pre-egg or pre-sperm cell starts out with 46 chromosomes.
During formation the number of chromosomes is cut in half so there are 2
cells each with 23 chromosomes. At fertilization then, each parent
contributes 23 for a new total in the baby of 46. However, in a trisomy, one
pair of chromosomes fails to separate, so that one sperm (or egg) gets 24 and
the other gets 23. If the one with 24 gets fertilized, the offspring will
now have 47 chromosomes instead of 46. If the pair that failed to separate
was the 13th pair, the result is Patau's. Most often embryos affected in
this way are spontaneously miscarried.
If they survive, there are a number
of characteristics abnormalities such as fusion of the eyes or the absence of
an eye, the nose is malformed, cleft lip and/or palate is present and the
head is small. There may be extra fingers and toes. There can also be an
extra spleen, abnormal liver structure,rotated intestines and an abnormal
pancreas. Affected individuals usually do not progress developmentally
the six-month level. (Human Genetics, R. Lewis. 4th ed.)
This is a trisomy (3 copies) of the 13th chromosome and occurs in about
1:5000 births..., 20% survive beyond 1 year. Check the human genome
web-site form more info...They should have quite a bit more on this than I
have in my head.
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Update: June 2012