Non-syndromic hearing impairment in a multi-ethnic population of Northeastern Brazil

Abstract

SUMMARYObjective: There are many hearing impaired individuals in Monte Santo, a rural municipality in the state of Bahia, Brazil, including multiple familial cases strongly suggestive of a genetic aetiology.Methods: The present study investigated 81 subjects with hearing impairment (HI) recruited from 36 families. Mutations previously associated with HI were initially analyzed: c.35delG in gene GJB2, del(GJB6-D13S1830) and del(GJB6-D13S1854) in gene GJB6, and A1555G in the mitochondrial gene MTRNR1, with additional mutations in GJB2 identified by sequencing the coding region of the gene.Results: Seven different mutations were present in GJB2 with mutations c.35delG and p.R75Q, which are known to be pathogenic, identified in 37.0% of the subjects. Individuals homozygous for the c.35delG mutation were diagnosed in eight families, corresponding to 24.6% of unrelated individuals with nonsyndromic hearing impairment (NSHI), and an additional heterozygote for this mutation was present in a single family. Ten individuals (12.4%) in another family were heterozygous for the mutation p.R75Q. Conclusions:Significant heterogeneity was observed in the alleles and patterns of NSHI inheritance among the subjects studied, probably due to the extensive inter-ethnic admixture that characterizes the peoples of Brazil, and a high prevalence of community endogamy and consanguineous marriage.

Targeted Resequencing of Deafness Genes Reveals a FounderMYO15AVariant in Northeastern Brazil

“…Its population has been estimated at 54,733 (IBGE, ). Only a few HL studies have focused on the northeast region of Brazil (Manzoli et al., ; Melo et al., ); our data greatly expands what is known about the genetics of HL in this region and facilitates diagnostic etiology there. The variant p.(Val1400Met) in MYO15A is the most frequently identified.…”

“…Evidence of the genetic etiology of HL in Brazil has been demonstrated by a number of independent studies (Pfeilsticker et al., ; Piatto et al., ; Bernardes et al., ; de Oliveira et al., ; Christiani et al., ; Batissoco et al., ; Cordeiro‐Silva et al., ; Motta et al., ; Castro et al., ; Manzoli et al., ; Ramos et al., ; Melo et al., ; Moreira et al., ). Most studies present data representative of Brazil's southeast region, while few studies show genetic HL data from the north and northeast regions.…”

Genealogical data in population medical genetics: field guidelines

“…For instance, no reference was found in Aicuña to the long civil war occurred in that Argentine province, La Rioja, during the 19 th century (Castilla and Adams, 1996), or to the Guerra de Canudos in the military garrison, Monte Santo, in the late 1890s (Manzoli et al ., 2013). …”

Estudo do Papel do Gene SLC26A4 na Surdez Neurossensorial Não-Sindrômica Pré-Lingual em uma Série de Casos no Sudeste Brasileiro

“…Entretanto, os tipos e freqüências das mutações são fortemente influenciados pela composição étnica da população. Na população brasileira, estudos apontam a presença de c.35delG em homozigose em 3,9 a 24,1% dos casos estudados no Nordeste e Sudeste do país (CORDEIRO-SILVA et al, 2011;MANZOLI et al, 2013 aminoglicosídeos está associada a um efeito aditivo destes danos (PREZANT et al, 1993;ESTIVILL et al, 1998b;OLIVEIRA et al, 2007;ITO et al, 2010). A freqüência desta alteração na população não é tão alta quanto aquela encontrada para os genes GJB2 e GJB6.…”

“…A freqüência desta alteração na população não é tão alta quanto aquela encontrada para os genes GJB2 e GJB6. Alguns estudos têm relatado a ausência desta alteração na população brasileira e, quando m.1555A>G é encontrada, se apresenta em freqüências muito baixas (0,46%) (OLIVEIRA et al, 2007;MANZOLI et al, 2013;MELO et al, 2014;QIAN et al, 2014).…”