Hyperpipecolic acidemia: clinical and biochemical observations in two male siblings.

Hyperpipecolic acidemia was diagnosed in two male siblings. Both infants had an unusual constellation of clinical findings including hepatomegaly, retinopathy, developmental delay, and several minor dysmorphic features. Pipecolic acid values were elevated in serum, urine, and in liver tissue, but none was detected using an automated amino acid analyzer. The older sibling died at 18 months of age. The younger sibling has been treated with a protein-restricted diet, with lowering of the serum pipecolic acid concentration. He is alive at 18 months of age; there has been no apparent progression in his liver disease or retinopathy since therapy began, but he remains developmentally delayed.