Mucopolysaccharidosis VI

Mucopolysaccharidosis VI; MPS VI; MPS 6Maroteaux-Lamy syndromeN-acetylgalactosamine 4-sulfatase deficiencyArylsulfatase B deficiency; ASB deficiencyMucopolysaccharidosis VI (MPS VI) or Maroteaux-Lamy syndrome (MIM # 253200) is an autosomal recessive lysosomal storage disorder described in 1963 by Dr. Pierre Maroteaux and Dr. Maurice Lamy [1] and determined by mutations in the arylsulfatase B (ARSB) gene located in chromosome 5 (5q13-5q14)[2]. Pathogenic mutations of this gene result in reduced or absent activity of the enzyme arylsulfatase B (ASB) also called N-acetylgalactosamine 4-sulfatase (E.C.3.1.6.12) leading to incomplete degradation and cellular accumulation of the glycosaminoglycan(s) (GAG), (previously also known as a "mucopolysaccharide" dermatan sulfate (DS)), and cell injury. Another GAG, chondroitin 4-sulfate (CS), is also a substrate for ASB [3,4] but is hydrolyzed by hyaluronidase and β-glucuronidase to trisaccharides and higher oligosaccharides that also accumulate but are not recognized as "classic storage material" [J Hopwood, personal communication]. Clinical manifestations are related to progressive accumulation of DS GAG and sulfated oligosaccharides derived from both DS and CS in lysosomes, cells and tissues.The epidemiological studies of MPS VI are limited to publications describing birth prevalence whereas no studies describing population prevalence are available. These birth prevalence studies are based on clinical identification of patients and regional birth rate [5] as represented in Table 1. They range from 1 in 43,261 births in Turkish immigrants living in Germany [6] to 1 in 1,505,160 births in Sweden [7]. Because these birth prevalence estimates are derived from patient referrals based mostly on clinical identification, (except for a single publication that mentions prenatal diagnosis for one patient in Australia [8]), they will be underestimates of the true birth prevalence, which will only be determined when newborn screening becom