Gaucher disease in North Macedonia: Unexpected prevalence of the N370S GBA1 allele with attenuated disease expression.

The majority of Gaucher Disease (GD) cases result from pathologic mutations in the GBA1 gene. A rich mutational spectrum of about 500 identified variants has been recognized. The disease is characterized by phenotypic diversity. Data regarding the genotype-phenotype correlation are scanty and inconclusive. Here, we summarize the genetic and phenotypic "portraits" of 14 patients with GD type 1 in the Republic of North Macedonia, 4 of Macedonian and 10 of Albanian origin. Altogether, 6 variants were detected, compounding 6 different genotypes. All genotypes contained the N370S variant, which was detected with an overall prevalence of 60.7%. Other frequent variants included the 1263del55 deletion and the double mutant allele D409H;H255Q, each with a prevalence of 14.2%. We detected two rare mutations: W92* - a pathogenic nonsense mutation and D399N - a single nucleotide variant of uncertain pathogenicity. The most common genotypes were N370S/1263del55 and H255Q;D409H/N370S, both present in 4/14 patients, followed by N370S homozygosity (3/14). Splenomegaly was the most common clinical manifestation, identified in all patients. Hepatomegaly was less frequent and was present in 50% of cases. Thrombocytopenia was present in 9/14, while half of the patients had anemia. Bone pathology was demonstrated in 8 patients. Patients with different genotypes displayed a high degree of phenotypic heterogeneity, suggesting that the other allele determines the onset and severity of the disease in patients with the N370S mutation. Longer follow-up, bigger cohorts of patients and multicentric studies should be conducted to further define the association between the genotypic and phenotypic expression in GD.