STRIDOR AS THE MAJOR PRESENTING SYMPTOM IN RIBOFLAVIN-RESPONSIVE MULTIPLE ACYL-COA DEHYDROGENATION DEFICIENCY

Inspiratory strider of unknown origin was the leading clinical symptom in an Ii-month-old boy. The strider increased over a period of 4 week s, and assisted ventilation became necessary. Selective urinary screen ing by gas chromatography/mass spectrometry analysis revealed excretio n of ethylmalonic and 3-OH-isovaleric acid and of N-isobutyryl-, N-2-m ethylbutyryl-, N-isovaleryl-, N-hexanoyl- and N-suberylglycine. Neithe r hypoglycaemia nor metabolic acidosis were noticed. Treatment with 20 0 mg of riboflavin per day led to a dramatic clinical improvement with restoration of normal respiration and an increase in muscular tone wi thin 2 months, During this period, metabolite excretion in urine compl etely normalized. Riboflavin-sensitive multiple acyl-CoA dehydrogenati on deficiency was confirmed in cultured fibroblasts. With riboflavin s upplementation, the development of the child has been favourable, with normal school attendance now at an age of 9 years. Conclusion As resp iratory symptoms might precede other symptoms in disorders of mitochon drial oxidation, we propose determination of urinary organic acids in all cases of unexplained laryngeal strider.