Some properties of fibroblasts from a patient with debrancher deficiency.

Glycogenosis Type III is characterized by a deficiency of debranching enzyme (amylo-1,6-glucosidase, E.C. 3. 2. 1. 33) in most tissues. Low activity of liberating glucose from limited dextrin in the biopsied muscle can be demonstrated in a patient with this disease. We cultured fibroblasts from a skin biopsy from a patient with debrancher deficiency and examined the metabolism of glycogen in these cultured fibroblasts. Debrancher activity in the post-mitochondrial supernatant obtained from these fibroblasts showed a good concentration dependent manner but had approximately half of that from normal human fibroblasts (YH-1). Although the enzymatic activity of debrancher in the cultured fibroblasts from the skin was reduced essentially to the same levels as observed in muscle biopsy, little glycogen granules were accumulated in the cytoplasm of these fibroblasts as revealed by either light- or electron-microscopic observation. The fibroblasts obtained in the present study may be useful for the analysis of molecular mechanism of the debrancher deficiency disease, glycogenosis Type III.