Fragile X syndrome and acute lymphoblastic leukemia.

Fragile X [Fra(X)] syndrome is an example of a heritable fragility syndrome associated with mental retardation. It is characterized by a fragile site on the X chromosome at Xq27-28. There have recently been three reports of malignant solid tumors associated with Fra(X) syndrome. We describe the first case of a hematologic malignancy [T-cell acute lymphocytic leukemia (ALL)] in a patient with Fra(X) syndrome. The possibility of a predisposition to malignancy in Fra(X) is discussed.