Familial translocation (X;3) (p22.3;p23): chromosomal in situ suppression (CISS) hybridization and inactivation pattern study

High-resolution chromosome banding and chromosomal in situ suppression hybridization were used to identify a derivative X in a 10-month-old female patient with congenital heart defect and slight dysmorphism. The unbalanced karyotype was monosomic for Xp22.3-pter and trisomic for 3p23-pter regions. The derivative X was inherited from the mother carrier of a balanced translocation (X;3) (p22.3;p23). Replication study of the patient showed the abnormal X,t(X;3) to be late replicating, except for the translocated segment. This patient demonstrated only epicanthus and congenital heart defect, despite her partial trisomy 3. The clinical phenotype may be less severe when the X-chromosome is involved in an unbalanced translocation.