X AUTOSOME TRANSLOCATION IN 3 GENERATIONS ASCERTAINED THROUGH AN INFANT WITH TRISOMY 16P DUE TO FAILURE OF SPREADING OF X-INACTIVATION/

We report on a reciprocal translocation t(X;16)(q28;p12) detected in a newborn girl with clinical manifestations of partial trisomy 16p, A b alanced translocation was found in the mother and in the maternal gran dmother, Replication studies on lymphocytes and fibroblasts showed non random X-inactivation in both the patient and her mother. In the mothe r, the derivative X (der(X)) was active, whereas the normal X was late replicating, In contrast, in the patient the der(X) was late replicat ing, and there was no spreading of X-inactivation onto the autosomal s egment, thus giving an explanation for the full clinical picture of pa rtial trisomy 16p. (C) 1996 Wiley-Liss, Inc.