Mutation analysis of the arylsulfatase B gene among Egyptian patients with Maroteaux–Lamy disorder

Abstract

Background Mucopolysaccharidosis type VI (Maroteaux-Lamy syndrome) (OMIM: # 253200), is an autosomal recessive lysosomal storage disorder. It is caused by deficiency of the enzyme arylsulfatase B (ARSB), also known as N-acetylgalactosamine-4-sulfatase. ARSB is responsible for the degradation of the glycosaminoglycans dermatan sulfate and chondroitin 4-sulfate. Deficiency of the ARSB enzyme leads to accumulation of partially degraded dermatan sulfate in the lysosomes especially in connective tissues leading to clinical complications. Aim This study aimed at identifying the molecular basis of MPS VI (Mucopolysaccharidosis VI) among 15 Egyptian patients. Method Patients were from 15 families, age ranged from 1year and 5 months to 11 years and 9 months(5.19±0.8) with parental consanguinity in 11 families out of 15 (73.3%). All patients were subjected to all necessary clinical, radiological and biochemical assessments. Molecular assessment was carried out by sequencing the 8 coding exons of the ARSB gene for the fifteen studied patients. Results The disease causing mutations were revealed in 13 patients. Four novel mutations; c.257delA, c.189insA, p.Ser94Leu and p.Leu51Pro were identified as well as four previously reported mutations; p.Leu82Arg, p.Ser96Arg, p.Arg160X and p.Arg160Gln. Conclusion The study highlights the heterogeneity of the mutational pattern which was obvious in finding novel mutations in homozygous forms in approximately 40% of the studied patients. Exons 1 and 2 seem to carry most of the mutations in the Egyptian MPS VI patients. Arginine at position 160 seems to be the most abundant mutational hot spot in the Egyptian MPS VI patients.