Epidemiology and Genetics of Mucopolysaccharidosis Type VI in Russia.

Mucopolysaccharidosis VI (MPS VI) is an autosomal recessive lysosomal storage disease caused by mutations in the arylsulfatase B gene (ARSB) and consequent deficient activity of ARSB, a lysosomal enzyme involved in the glycosaminoglycan (s) (GAGs) metabolism. Here, we present the results of the study of ARSB DNA analysis in MPS VI patients in the Russian Federation (RF) and other republics of the Former Soviet Union. In a cohort of 68 patients (57 families) with MPS VI, a total of 28 different pathogenic alleles were found. The most prevalent nucleotide changes included NM_000046.5:c.194C>T and NM_000046.5:c.454C>T. Five pathogenic alleles were novel, not previously reported (NM_000046.5:c.304C>G, NM_000046.5:c.533A>G, NM_000046.5:c.941T>C, NM_000046.5:c.447_456del10, and NM_000046.5:c.990_10003del14). The nucleotide variant NM_000045.6:c.454C>T was the prevalent allele among Slavic Russian patients. The nucleotide variant NM_000045.6:c.194C>T was found only in MPS VI families from the Republic of Dagestan. Based on the analysis of dry blood spots (DBSs) collected from newborns in this RF region, we showed the frequency of this mutant allele in the Republic of Dagestan to be 0.01 corresponding to the MPS VI frequency of nearly 1:10,000, which is one of the highest worldwide. This may eventually make the selective asymptomatic carrier test and newborn screening highly feasible in this region of the country.

Novel mutations in arylsulfatase A gene in three Ukrainian families with metachromatic leukodystrophy.

Metachromatic leukodystrophy (MLD) is a lysosomal storage disease caused by the deficiency of arylsulfatase A (ARSA) or saposin B. The majority of mutations identified in patients with MLD are unique within individual families. Here, we report on the novel missense mutations (F247S, D381E, and A469G) and the known mutations "A" allele and P136S in the ARSA gene in three unrelated Ukrainian families with MLD. The mutations F247S and P136S were found in compound heterozygous with the "A" allele in two patients with juvenile onset MLD. The clinical features of the typical patient with genotype D381E/A469G (early onset with very rapid manifestation of disease) suggest the reason to distinguish an early infantile MLD variant.