Brachyolmia: a skeletal dysplasia with an altered mucopolysaccharide excretion

A 15-year-old girl is described with brachyolmia. She presented with short-trunked dwarfism, hypolordosis of the lower spine and radiological features of the disease. She was initially considered to have a mucopolysaccharidosis (type III Sanfilippo) on account of a pathological urinary glycosaminoglycan excretion pattern. The amount of urinary glycosaminoglycans was normal, but we found an increased amount of an undersulphated chondroitin sulphate molecule. Our finding of an undersulphated glycosaminoglycan points to a disturbance in chondroitin sulphate synthesis, and it is rare that a defect in glycosaminoglycan synthesis leads to a skeletal dysplasia. To our knowledge, this is the second case of brachyolmia with a possible defect in chondroitin sulphate-sulphotransferase.