Essential Pentosuria: Renal or Enzymic Disorder

ESSENTIAL pentosuria is a rare, recessive genetic metabolic disorder characterized by the excretion of gram quantities of L -xylulose. It was included among Garrod's “inborn errors of metabolism” 1 and has usually been considered to be the result of an enzyme deficiency. Garrod's original concept of a hereditary metabolic anomaly has been broadened by some to include renal defects, and, in regard to essential pentosuria, Knox 2 has recently stated, “the paramount question of a renal or an enzymic mechanism is still to be decided”.