Occurrence of acute leukemia in females in a genetically isolated population.

Acute lymphoblastic leukemia was found in six young females in a genetically isolated Syrian Jewish Community in Brooklyn, N.Y. over a 15-year period. This represents a frequency 30 times greater than the expected rate. In this community the frequency of first cousin marriages is estimated to be seven percent. Three cases were related on their maternal side, the parents of a fourth case were themselves related as were both sets of grandparents of a fifth case. In two families a history of infertility was present. On average, fathers of the cases were 5.5 years older at birth of the cases than a matched sample of community controls and 7.2 years older than a matched sample of non-community controls. The high frequency of consanguinity and the older age of the fathers may increase risk to acute leukemia for young girls in this community.