PathwayStep1110 PathwayStep4270 Defective GALNS does not hydrolyse sulfate from Gal6S Glycosaminoglycan metabolism MPS IV - Morquio syndrome A Authored: Jassal, B, 2012-04-26 Edited: Jassal, B, 2012-04-26 Mucopolysaccharidosis IV A (MPS IVA, MPS4A, Morquio's syndrome, Morquio's; MIM:253000) is a rare, autosomal recessive mucopolysaccharide storage disease, first described simultaneously in 1929 by L Morquio (Morquio L, Sur une forme de distrophie familiale, Bull Soc Pediat, Paris, 27, 1929, 145-152) and JF Brailsford (Brailsford, JF, Chondro-osteo-dystrophy: roentgenographic and clinical features of child with dislocation of vertebrae, Am j Surg, 7, 1929, 404-410). MPSIVA is caused by a deficiency in N-acetylgalactosamine 6-sulfatase (GALNS; MIM:612222) which normally hydrolyses 6-sulfate groups of N-acetylgalactosamine 6-sulfate units of chondroitin sulfate (CS) and of galactose 6-sulfate units of keratan sulfate (KS) (Matalon et al. 1974). The result is accumulation of KS/DS in cells and overexcretion in urine. Severe osteochondrodysplasia is a commonly seen phenotype for this disease. The severity of the disease is variable but severe cases limits lifespan to their 20's or 30's (Prat et al. 2008, Tomatsu et al. 2011). The gene coding for human GALNS was mapped to chromosome 16q24.3 (Masuno et al. 1993) and its structure described at the same time by two independent groups as comprising 14 exons and spanning approximately 40-50 kb (Nakashima et al.1994, Morris et al.1994). Pubmed18456538 Pubmed21506915 Pubmed4218100 Pubmed8001980 Pubmed8020961 Pubmed8325655 Reactome Database ID Release 432206290 Reactome, http://www.reactome.org ReactomeREACT_147825 Reviewed: Alves, Sandra, 2012-08-27 Reviewed: Coutinho, Maria, 2012-08-27