Mild expression of 3qter trisomy due to a de novo (X;3)(p22.3;q25.3) translocation.

A 3-year-old girl was found to have a 3qter trisomy resulting from a de novo t(X;3)(p22.3;q25.3) with a mild expression of the imbalance. Replication studies revealed a late replicating der (X) in 86% of the scored lymphocytes with variable patterns of inactivation of the 3q segment.