Monosomy 7 syndrome in an infant with neurofibromatosis.

A 9-month-old boy with known familial neurofibromatosis type I (NF-1) presented with a clinical and laboratory picture suggestive of juvenile chronic myelomonocytic leukemia (JCMMoL). Chromosomal studies obtained from the bone marrow indicated, however, that he had monosomy 7 syndrome. We believe this is the first reported case of monosomy 7 syndrome in a child with NF in the United States, and that this case complements a recent report of two cases of NF, JCMMoL, and monosomy 7 in Japanese children. Since monosomy 7 syndrome is very difficult to differentiate from JCMMoL or acute nonlymphocytic leukemia (ANLL) unless appropriate chromosomal studies are obtained, we believe it is possible that monosomy 7 may occur with increased frequency in patients with NF-1. Monosomy 7 syndrome might therefore be a significant cause of the known association between NF-1 and nonlymphoid leukemia.