Slavic populations are also characterized by a high occurrence of pan-European FAH c.554-1G>T (e.g., 42% of pathogenic alleles in Russian patients) and c.1062 + 5G>A (17% of pathogenic alleles in Russian patients) variants, which are associated with the development of hereditary tyrosinemia type I [43], as well as increased frequency of IDS (iduronate-2 sulfatase) alleles c.253G>A, c.257C>T, c.263G>A, c.998C>T, c.1327C>T, and c.1403G>A, which are linked to Hunter’s syndrome (mucopolysaccharidosis type 2) [44,45]. The gene discussed is IDS; the disease is mucopolysaccharidosis type 2.