THIS communication describes our preliminary findings on 2 children who have what appears to be a hitherto undescribed inborn error of metabolism.Case ReportsCase 1. M.M., a 3-year-old girl, was first seen in February, 1960, because of retardation of speech. The mother had had some vaginal bleeding in the 3d and an attack of rubella in the 7th month of pregnancy. The child was born normally at term and weighed 3.3 kg. (7 pounds, 2 ounces). She suffered several respiratory infections in infancy and, at the age of 1 year, had an attack of diarrhea lasting for 3 weeks. . . .