Trisomy 9 mosaicism in two girls with multiple congenital malformations and mental retardation.

Two girls with mosaicism for an extra chromosome 9 are reported. Clinical findings included growth and mental retardation, facial dysmorphism, delayed ossification, single flexion crease, gastro-oesophageal reflux in one girl, and ventricular and atrial septal defects in the other patient. These findings are compared to the other previously reported cases of trisomy 9 mosaicism.