ABSTRACT
INTRODUCTION: Spinocerebellar ataxia type 2 (SCA2) is a dominant neurodegenerative disorder due to expansions of a CAG repeat tract (CAGexp) at the ATXN2 gene. Previous studies found only one ancestral haplotype worldwide, with a C allele at rs695871. This homogeneity was unexpected, given the severe anticipations related to SCA2. We aimed to describe informative ancestral haplotypes found in South American SCA2 families. METHODS: Seventy-seven SCA2 index cases were recruited from Brazil, Peru, and Uruguay; 263 normal chromosomes were used as controls. The SNPs rs9300319, rs3809274, rs695871, rs1236900 and rs593226, and the STRs D12S1329, D12S1333, D12S1672 and D12S1332, were used to reconstruct haplotypes. RESULTS: Eleven ancestral haplotypes were found in SCA2 families. The most frequent ones were A-G-C-C-C (46.7 % of families), G-C-C-C-C (24.6 %) and A-C-C-C-C (10.3 %) and their mean (sd) CAGexp were 41.68 (3.55), 40.42 (4.11) and 45.67 (9.70) (p = 0.055), respectively. In contrast, the mean (sd) CAG lengths at normal alleles grouped per haplotypes G-C-G-A-T, A-G-C-C-C and G-C-C-C-C were 22.97 (3.93), 23.85 (3.59), and 30.81 (4.27) (p < 0.001), respectively. The other SCA2 haplotypes were rare: among them, a G-C-G-A-T lineage was found, evidencing a G allele in rs695871. CONCLUSION: We identified several distinct ancestral haplotypes in SCA2 families, including an unexpected lineage with a G allele at rs695871, a variation never found in hundreds of SCA2 patients studied worldwide. SCA2 has multiple origins in South America, and more studies should be done in other regions of the world.
Subject(s)
Nerve Tissue Proteins , Spinocerebellar Ataxias , Humans , Ataxins/genetics , Nerve Tissue Proteins/genetics , Spinocerebellar Ataxias/genetics , Alleles , HaplotypesABSTRACT
A mucopolissacaridose tipo VI (MPS VI) é uma doença rara causada pela deficiência da enzima lisossômica arilsulfatase B, com consequente acúmulo de glicosaminoglicanos (GAGs) em vários tecidos, incluindo o cardiovascular. Com o objetivo de descrever as manifestações cardiovasculares na MPS VI, uma das principais causas de óbito, seis pacientes (4 a 13 anos) foram avaliados por exame físico, eletrocardiograma e ecocardiograma. Todos os pacientes, exceto a paciente com a menor idade, apresentaram sopro cardíaco e alterações ecocardiográficas. Os 6/6 pacientes apresentaram, no eletrocardiograma, desvio do eixo cardíaco para a direita, associado à sobrecarga atrial esquerda (1/6) ou distúrbio de condução (1/6).
