Continuation of a case report.

We previously reported on two male sibs with an unknown syndrome which included microcephaly, seizures, mental retardation, congenital heart disease, and skeletal abnormalities.' The subsequent clinical course and necropsy findings of one of the boys (sib 2) contribute substantial information to the original report. At 15 months of age he had findings of a large atrial septal defect with significant left to right shunt and signs of congestive heart failure. At 22 months of age he was admitted to the hospital in status epilepticus of new onset for which no aetiology was determined. At 29 months of age he had new and striking findings of pulmonary artery hypertension not previously observed. Cardiac catheterisation showed marked pulmonary artery hypertension with markedly raised pulmonary vascular resistance (10 units/M2n) and a small left to right atrial shunt. The ventricular, septal defect was closed. Oxygen breathing failed to reduce pulmonary vascular resistance. At 36 months ofage he required oxygen up to 4 1/min because of increased tachypnoea, respiratory distress, and lack of energy. At 39 months of age he suddenly deteriorated and was dead on arrival in the emergency department of a local hospital. Necropsy findings showed marked right ventricular hypertrophy and dilatation, dilatation and hypertrophy of the main pulmonary artery and its branches, and hypoplasia of the left atrium, left ventricle, and the entire aorta. There was a 2 cm atrial septal defect partially closed and no ventricular septal defect. The right ventricular wall thickness was 1 7 cm, the left ventricular wall thickness was 07 cm (normal). The aortic diameter was 0 9 cm at the root, 0-6 cm at the arch, and 0 5 cm at the descending thoracic