ABSTRACT
Mucopolysaccharidosis (MPS) IVA is a rare autosomal recessive disease with a highly variable distribution worldwide. Discrepancies in the incidence of MPS IVA among populations of different ethnicities are mostly attributed to founder effects. Demographic and clinical data from 28 MPS IVA patients, followed at a single center, and ancestry (Y chromosome and mitochondrial markers) of a subsample of 17 patients, most with the p.Ser341Arg (c.1023C>G) mutation were analyzed. Parental consanguinity was observed in 15/20 couples; a rare homozygous N-acetylgalactosamine-6-sulfatase (GALNS) mutation was found in 7/16 families with intra-familial phenotypic heterogeneity. Paternal ancestry was 94.2% (16/17) European, 5.8% (1/17) African, and 0% Amerindian. The European paternal haplogroups R1a, R1b, and R* accounted for 94.2% (16/17) of the patients. The R1b haplogroup, identified in 59% (10/17) of the patients, is frequently found in populations from the Iberian Peninsula. European, Amerindian, and African maternal ancestry was observed in 46.9% (8/17), 35.4% (6/17), and 17.7% (3/17) of the patients, respectively. Study of a cluster of MPS IVA patients from Northeastern Brazil, with high parental consanguinity and phenotypic heterogeneity showed predominantly European parental ancestry. This ancestry finding corroborates historical data on the local settlement, formed predominantly by European men.
Subject(s)
Chondroitinsulfatases/genetics , Genetic Heterogeneity , Haplotypes/genetics , Mucopolysaccharidosis IV/genetics , Adolescent , Adult , Amino Acid Sequence/genetics , Black People/genetics , Brazil/epidemiology , Child , Chromosomes, Human, Y , Consanguinity , DNA, Mitochondrial/genetics , Demography/statistics & numerical data , Female , Humans , Male , Middle Aged , Mucopolysaccharidosis IV/epidemiology , Mucopolysaccharidosis IV/pathology , Mutation, Missense , Young AdultABSTRACT
Alpha thalassemia and beta-globin haplotype are considered classical genetic disease modifiers in sickle cell anemia (SCA) causing clinical heterogeneity. Nevertheless, their functional impact on SCA disease emergence and progression remains elusive. To better understand the role of alpha thalassemia and beta-globin haplotype in SCA, we performed a retrospective study evaluating the clinical manifestations of 614 patients. The univariate analysis showed that the presence of alpha-thalassemia -3.7-kb mutation (αα/-α and -α/-α) decreased the risk of stroke development (p = 0.046), priapism (p = 0.033), and cholelithiasis (p = 0.021). Furthermore, the cumulative incidence of stroke (p = 0.023) and cholelithiasis (p = 0.006) was also significantly lower for patients carrying the alpha thalassemia -3.7-kb mutation. No clinical effects were associated with the beta-globin haplotype analysis, which could be explained by the relatively homogeneous haplotype composition in our cohort. Our results reinforce that alpha thalassemia can provide protective functions against hemolysis-related symptoms in SCA. Although, several genetic modifiers can impact the inflammatory state of SCA patients, the alpha thalassemia mutation remains one of the most recurrent genetic aberration and should therefore always be considered first.
