A fragile X female with Down syndrome.

Clinical and cytogenetic aspects of a female infant with trisomy 21 and the fragile X [fra(X)] chromosome are reported. Most of the facial characteristics of the patient are those observed in Down syndrome, but some features such as long face with prominent forehead and lower jaw, and large ears are related to the fra(X) syndrome. The origin of an additional chromosome 21 may be ascribed to maternal first meiotic nondisjunction in our case. It has been suspected that female carriers of the fra(X) chromosome may be predisposed to meiotic nondisjunctional events. However, there is probably no relationship between the two chromosomal abnormalities in our case because of the maternal age at the delivery.