Recurrence risks for down syndrome

摘要

The recurrence risks for Down syndrome due to an inherited translocation are estimated from empirical data in the literature for two maternal age groups: mothers under 30 and mothers 30 and over. These risks were found to be approximately 0.3 and 0.05, respectively. The probability for two Down syndrome sibs both having an inherited translocation was estimated as about 18.2 for the former age group and 2.7 for the latter. The relative effectiveness in preventing Down syndrome births by karyotyping affected children is discussed.