An infant girl, born small for gestational age, with abnormal single c
reases on the fifth digits, subsequent severe developmental delay, hyp
ertelorism, bilateral equinovalgus deformities, grade IV genitourinary
reflux and mild right hydronephrosis, was found to have an inverted d
uplication of the short arm of chromosome 16 [46,XX; inv dup (16) (p 1
3.3 --> p 11.2]. The cardiac anomalies included a large perimembranous
ventricular septal defect (VSD) and a moderate-sized atrial septal de
fect (ASD), Cardiac catheterization at 6 months of age revealed system
ic level pulmonary artery pressure, bilateral pulmonary venous desatur
ation, and in room air a pulmonary/systemic blood flow ratio (Qp/Qs) o
f 0.8:1.0, which did not change significantly with administration of o
xygen and nitric oxide, To our knowledge, this is the first descriptio
n of early nonreactive pulmonary vascular disease in a patient with du
plication 16p and a large VSD.