Morquio's disease type B (beta-galactosidase deficiency) in three siblings

The clinical and biochemical findings in 3 siblings with Morquio's disease type B (mucopolysaccharidosis (MPS) IV B) are presented. Their phenotype is characterised by short trunk dwarfism with kyphoscoliosis and thoracic deformity. Radiographic findings include general platyspondyly, dysplasia of the pelvis and epiphyseal abnormalities. The patients are of normal intelligence. In the urine of all 3 affected children abnormal oligosaccharide excretion was found by thin-layer chromatography and in 1 of them keratosulphaturia was detected. The clinical diagnosis was confirmed biochemically by demonstration of a profound deficiency of beta-galactosidase activity in cultured fibroblasts. The clinical picture is compared with that of other cases in the literature and the possible molecular basis of the different phenotypes of beta-galactosidase deficiency (variants of monosialo-ganglioside-1 (GM1)-gangliosidosis, Morquio's disease type B) is discussed.