Neonate with Down's syndrome and transient congenital leukemia. In vitro studies.

A white female neonate with clinical manifestations of Down's syndrome was found to have a peripheral white count of 74,000/mm3 with 65% blast forms. Bone marrow aspirate revealed 36% blasts. On chromosomal analysis of bone marrow and peripheral blood, two cell lines were found, one with trisomy 21 and another with pentasomy 21. Colony cultures on the patient's bone marrow cells revealed an adequate growth pattern of CFU/GM. Cells were reactive with myeloblast alloantisera. At the age of 3 weeks, peripheral counts were within normal limits as was morphology of the repeat bone marrow aspirate. Chromosome analysis at that time showed complete absence of pentasomy 21 cell line, and repeat cell colony studies revealed normal growth, differentiation, and maturation of CFU/GM. Maternal serum totally inhibited colony growth of the patient's remission marrow and allogeneic blast cells. This serum inhibitor actually disappeared 1 month postpartum. The patient has had no recurrence of blast cells up to the present age of 3 years.