Leber's congenital amaurosis associated with hyperthreoninemia

Two siblings had Leber's congenital amaurosis. The girl (Patient 1) showed blindness shortly after birth, absent pupillary light reflex, and multiple round, white spots in both fundi. Her serum threonine level was increased (2.0 to 5.3 mg/dl; normal, 0.78 to 1.82 mg/dl). She died of massive pericardial effusion four months after birth. Her brother (Patient 2) was nearly blind shortly after birth. He had a poor pupillary light reflex and a nearly extinguished electroretinographic response. He also had hyperthreoninemia, hyperthreoninuria, hepatomegaly, and mental and physical retardation. We suspect a close relationship between hyperthreoninemia and Leber's congenital amaurosis in these siblings.