Based on these findings, the patient had fibroblast testing to determine levels of alpha‐mannosidase (alpha‐mannosidosis, types I and II, MIM# 248500), arylsulfatase‐A (metachromatic leukodystrophy, MIM# 250100), beta‐galactosidase (GM1‐gangliosidosis, MIM# 230500 and mucopolysaccharidosis type IVB (Morquio), MIM# 253010), beta‐glucuronidase (mucopolysaccharidosis VII, MIM# 253220), cerebroside beta‐galactosidase (Krabbe disease, MIM# 245200), and hexosaminidase (Tay–Sachs disease, MIM# 272800), which were normal, thus excluding these disorders. The gene discussed is GLB1; the disease is mucopolysaccharidosis type 4B.