Red blood cell uridine sugar nucleotide levels in patients with classic galactosemia and other metabolic disorders.

While dietary galactose restriction eliminates the life-threatening complications of classic galactosemia, central nervous system and ovarian disease are still evident in these patients, despite milk restriction. Because of the possibility that reduced tissue levels of uridine diphosphate galactose (UDPgalactose), the product of the deficient enzyme, galactose-1-phosphate uridyltransferase, are the cause of these unexplained complications, we have measured the concentration of red blood cell (RBC) uridine sugar nucleotides in these patients, comparing their values not only with those of normal subjects, but also with those of children who have other metabolic disorders. RBC UDPgalactose and uridine diphosphate glucose (UDPglucose) levels were measured by high-performance liquid chromatography (HPLC) in 35 control subjects, 24 galactosemic patients, and 19 patients with inborn errors of amino acid, organic acid, or ammonia metabolism. The last group of patients served as dietary controls, as they were all on special low-protein diets that restricted milk intake. The mean levels of UDPgalactose in galactosemic children and adults were 38% and 54% lower, respectively, than the levels in normal children and adults. While only six of 19 galactosemic children had levels below the 95% confidence limit for normals, four of five galactosemic adults had levels of UDPgalactose in the low range. The mean UDPgalactose level in children with other metabolic diseases who were on a low-milk diet was also reduced by 38%, with a mean not significantly different from galactosemics. Compared with normal adults, the level of UDPglucose in galactosemic adults was also reduced by 29%, with three of five affected adults having UDPglucose values below the 95% confidence limit.(ABSTRACT TRUNCATED AT 250 WORDS)