Biotin deficiency in a glycogen storage disease type 1b girl fed only with glycogen storage disease-related formula.

Glycogen storage disease type I is an autosomal recessive disorder caused by the defect in the glucose-6-phosphate enzyme system. Frequent intake of glucose-containing glycogen storage disease formula, uncooked cornstarch, or both, are usually needed to maintain normal blood glucose level. We report a glycogen storage disease type 1b girl with biotin deficiency caused by an exclusive glucose-containing glycogen storage disease formula for years, presenting with the appearance of severe skin lesions, and diagnosed by urinary organic acid analysis by gas chromato-spectrometry, and blood acylcarnitine analysis by tandem mass-spectrometry.