X-linked lymphoproliferative syndrome. A new kindred with variable phenotypic expression.

A kindred with five affected maternally related male members showed variable phenotypic expression of the X-linked lymphoproliferative syndrome. In one of the children, agammaglobulinemia developed following infectious mononucleosis. His brother had aplastic anemia in infancy and 21/2 years later died of overwhelming pneumonia resulting from ornithosis. A third brother died of reticulum cell sarcoma. Two maternally related male cousins died of reticulum cell sarcoma of the neck.