Infantile Pyknocytosis in a Premature Dichorionic Diamniotic Twin.

Infantile pyknocytosis is a rare and self-limiting cause of hemolytic anemia in neonates. It can result in severe anemia and hyperbilirubinemia. The pathogenesis is unknown: a genetic origin has been discussed; however, based on the current literature it is not clear which genetic mutations should be considered. We present a case of a premature twin, in whom genetic screening was performed. Genetic mutations in 46 genes associated with hereditary hemolytic anemia and dyserythropoietic anemia were tested. No mutations were found. In infantile pyknocytosis, a genetic defect in these genes is unlikely.