ABSTRACT
Cartilage-hair hypoplasia syndrome (CHH) is an autosomal recessive disorder frequently linked to n.72A>G (previously known as n.70A>G and n.71A>G), the most common RMRP variant worldwide. More than 130 pathogenic variants in this gene have already been described associated with CHH, and founder alterations were reported in the Finnish and Japanese populations. Our previous study in Brazilian CHH patients showed a high prevalence of n.197C>T variant (former n.195C>T and n.196C>T) when compared to other populations. The aim of this study was to investigate a possible founder effect of the n.197C>T variant in the RMRP gene in a series of CHH Brazilian patients. We have selected four TAG SNPs within chromosome 9 and genotyped the probands and their parents (23 patients previously described and nine novel). A common haplotype to the n.197C>T variant carriers was identified. Patients were also characterized for 46 autosomal Ancestry Informative Markers (AIMs). European ancestry was the most prevalent (58%), followed by African (24%) and Native American (18%). Our results strengthen the hypothesis of a founder effect for the n.197C>T variant in Brazil and indicate that this variant in the RMRP gene originated from a single event on chromosome 9 with a possible European origin.
Subject(s)
Founder Effect , Hair , Hirschsprung Disease , Osteochondrodysplasias , Polymorphism, Single Nucleotide , Humans , Brazil , Hirschsprung Disease/genetics , Male , Osteochondrodysplasias/genetics , Osteochondrodysplasias/congenital , Female , Hair/abnormalities , RNA, Long Noncoding/genetics , Haplotypes , Primary Immunodeficiency Diseases/genetics , Hypotrichosis/genetics , Chromosomes, Human, Pair 9/genetics , ChildABSTRACT
A síndrome do X frágil é a causa mais comum de retardo mental herdado; entretanto, é subdiagnosticada na populaçäo pediátrica. Objetivamos, neste estudo, determinar as características clínicas pré e pós-puberais mais significativas observadas entre indivíduos que apresentam a mutaçäo no gene FMR-1, e que possam ser utilizadas como método de triagem dos pacientes que devem ser submetidos à análise molecular. A partir de protocolo clínico-laboratorial, foram analisados 104 indivíduos (92 do gênero masculino e 12 do feminino) portadores de retardo mental idiopático. 17 pacientes (14 do gênero masculino) apresentaram a mutaçäo completa. História familiar de retardo mental e contato ocular pobre foram os achados que se mostraram associados, de forma estatisticamente significante (p<0,05), aos pacientes com a síndrome do X frágil em idade pré e pós-puberal. Os pacientes em idade pós-puberal também diferiram dos controles em relaçäo à presença de orelhas grandes, fronte proeminente e macroorquidismo