The lottery of Life ?

[Hal.]

If 2 people who have Down's Syndrome have a child , what is the chance of that child having Down's Syndrome ?

[Ringer]

As far as I'm aware virtually all men with down syndrome are sterile, I would assume women have the same problem.

[Hal.]

Thanks Ringer !

 

 

[mooeypoo]

Actually, that's not true. It was ASSUMED men with down syndrome are sterile. That's not the case.

Read here: http://www.ds-health.com/issues.htm

 

Excerpt:

Significantly impaired fertility of both sexes is evident in the Down syndrome population (Rogers and Coleman, 1992). While males have long been assumed to be sterile, Sheridan reports one case of a cytogenetically normal male infant that was fathered by a man with Down syndrome (Sheridan et al, 1980). Women have impaired but still significant fertility: a number of reviews document women with Down syndrome carrying pregnancy to term and delivering infants with and without Down syndrome (Bovicelli et al, 1982; Rani et al, 1990). Infants born to mothers with Down syndrome are at increased risk for premature delivery and low birth weight (Bovicelli et al, 1982). Pregnancy outcomes obtained from a study of mothers with Down syndrome are displayed in Table 5. Whether a woman with Down syndrome constitutes a high risk pregnancy depends largely on cognitive level and medical status. Obviously, the presence of maternal cardiac, thyroid, or hepatic disease, as well as seizure disorder, complicates a pregnancy. The high incidence of congenital heart disease in any offspring with Down syndrome contributes to pregnancy risk, including stillbirth and neonatal death (Gordon, 1990). Offspring without Down syndrome have a greater than average number of congenital anomalies (Bovicelli et al 1982) (see Table 5).

 

Table 5 in that site (right under that excerpt) has the information the OP was looking for.

[Neotropic]

I did a quick google search, and I found this on wikipedia.

 

There has been reported some cases of Down syndrome parents having trisomy 21 children.^[5] In these cases (all from mothers), the ovaries were trisomy 21, leading to a secondary nondisjunction during gametogenesis and a gamete with an extra chromosome 21. Such Down syndrome trisomies are indistinguishable from Down syndrome trisomies created through meiotic nondisjunction.

 

Here is the whole article, it may answer your question. ( I don't really know)

 

http://en.wikipedia.org/wiki/Genetic_origins_of_Down_syndrome