Variants in BTD (c.1270G > C; p. Asp424His); ASL (c.1300G > T; p.Val434Leu); GBE1 (c.985A > G; p.Tyr329Cys); and AGL (c.113C > G; p.T38S) have broadened the spectrum of mutations in these genes and provided additional evidence of involvement of these genes, when mutated, in various metabolic diseases. Here, GBE1 is linked to metabolic disease.