Familial infantile pyknocytosis in association with pulmonary hypertension.

Infantile pyknocytosis is a rare condition characterized by transient neonatal hemolytic anemia associated with increased pyknocyte count on blood smear. We describe three siblings with infantile pyknocytosis, born to consanguineous parents. The first and third siblings had neonatal hemolytic anemia that resolved spontaneously at 6 months. The second sibling presented at 11 days with severe hemolytic anemia along with pulmonary hypertension. He died at 39 days from sepsis. The findings support a possible autosomal recessive inheritance. We hypothesize that pulmonary hypertension may be secondary to or aggravated by neonatal hemolysis.