Amino acid metabolism in Friedreich's ataxia.

A study of amino acids determined by sequential Multi-sample Amino Acid Automatic Analyzer in plasma, urine and cerebrospinal fluid (CSF) in patients with Friedreich's ataxia and control subjects has revealed a number of mathematically significant variations from normal. Of practical physiological importance are the following: a high urinary excretion of alanine with slightly elevated plasma levels; a low plasma and CSF concentration of aspartic acid in the presence of normal urinary values and finally a low CSF concentration of taurine accompanied by normal plasma levels, but elevated urinary output and renal clearance rates. We postulate that the modifications in alanine and aspartic acid are less specific and probably secondary, but there could be a genetic defect in the membrane transport of taurine and the other beta-amino acids in Friedreich's ataxia.