Phenylketonuria in Indian children.

Three untreated phenylketonuric Indian children aged respectively 3 1/2 years, 1 1/2 years and 1 year showed rapid neurological deterioration. Plasma, cerebrospinal fluid and urine phenylalanine concentrations were significantly raised and the phenylalanine-tyrosine ratio was high. Analysis of a biopsy of the right frontal lobe of the brain in one case showed the myeline lipids--cerebroside and sulphatide--to be decreased. The total cerebroside in white matter was low. Light microscopy showed marked pallor of the white matter of the brain and extensive spongy degeneration. Ultrastructurally these spongy vesicles are located between the lamellae of the myelin sheath.