Double primary cancers in 2 young sibs, leukemia in another, and dextrocardia in a fourth

Two brothers developed multiple primary neoplasms in childhood; one had glioblastoma and non-Hodgkin's lymphoma at age 11 years, and the other brain tumor and acute leukemia at six years. A third brother died with myelogenous leukemia at thre years, and a fourth with cyanotic congenital heart disease at 11 weeks. Each child also had at least one hamartomatous lesion of the skin. The clinical features suggested von Recklinghausen's neurofibromatosis or other inherited cancer syndrome, but laboratory studies identified no markers of susceptibility to familial neoplasia.