title: Genetic Basis of Nonsyndromic Sensorineural Hearing Loss in the Sub-Saharan African Island Population of São Tomé and Príncipe: The Role of the DFNB1 Locus?
abstract: Hearing loss (HL) is a common condition with both genetic and environmental causes, and it greatly impacts global health. The prevalence of HL is reportedly higher in developing countries such as the Sub-Saharan African island of São Tomé and Príncipe, where the deaf community is estimated to be less than 1% of the population. We investigated the role of the DFNB1 locus (GJB2 and GJB6 genes) in the etiology of nonsyndromic sensorineural hearing loss (NSSHL) in São Tomé and Príncipe. A sample of 316 individuals, comprising 136 NSSHL patients (92 bilateral, 44 unilateral) and 180 controls, underwent a clinical and audiological examination. Sequencing of the GJB2 coding region and testing for the (GJB6-D13S1830) and del(GJB6-D13S1854) GJB6 deletions were performed. A total of 311 out of 316 individuals were successfully analyzed regarding the GJB2 and GJB6 genetic variations, respectively. The frequency of the GJB2 coding mutations in patients and controls was low. Some of those coding mutations are the most commonly found in Eurasian and Mediterranean populations and have also been identified in Portugal. None of the GJB6 deletions was present. The presence of certain coding variants in São Tomé and Príncipe suggests a non-Sub-Saharan genetic influx and supports the previously reported genetic influx from European (mainly Portuguese) ancestors. In summary, DFNB1 locus does not appear to be a major contributor to NSSHL in São Tomé and Príncipe. However, the presence of both pathogenic and likely pathogenic mutations in GJB2 suggests that GJB2-related NSSHL might still occur in this population, warranting further research on GJB2 testing in NSSHL cases.
authors: 1 Otolaryngology Department, Nova Medical School/Faculty of Medical Sciences , Universidade Nova de Lisboa, Lisboa, Portugal .|2 Hospital CUF Infante Santo , Otolaryngology Department, Hospital CUF Infante Santo, Lisboa, Portugal .
authors: Cristina
authors: C
authors: Caroça
authors: 3 Deafness Research Group, Biomedicine and Translational Research, BioISI, Faculty of Sciences, University of Lisbon , Lisbon, Portugal .
authors: Tiago Morim
authors: TM
authors: de Matos
authors: 2 Hospital CUF Infante Santo , Otolaryngology Department, Hospital CUF Infante Santo, Lisboa, Portugal .
authors: Diogo
authors: D
authors: Ribeiro
authors: 2 Hospital CUF Infante Santo , Otolaryngology Department, Hospital CUF Infante Santo, Lisboa, Portugal .
authors: Vera
authors: V
authors: Lourenço
authors: 2 Hospital CUF Infante Santo , Otolaryngology Department, Hospital CUF Infante Santo, Lisboa, Portugal .
authors: Tânia
authors: T
authors: Martins
authors: 2 Hospital CUF Infante Santo , Otolaryngology Department, Hospital CUF Infante Santo, Lisboa, Portugal .
authors: Paula
authors: P
authors: Campelo
authors: 3 Deafness Research Group, Biomedicine and Translational Research, BioISI, Faculty of Sciences, University of Lisbon , Lisbon, Portugal .
authors: Graça
authors: G
authors: Fialho
authors: 4 Centre for Toxicogenomics and Human Health (ToxOmics), NOVA Medical School , Faculty of Medical Sciences, Universidade Nova de Lisboa, Lisboa, Portugal .
authors: Susana Nunes
authors: SN
authors: Silva
authors: 1 Otolaryngology Department, Nova Medical School/Faculty of Medical Sciences , Universidade Nova de Lisboa, Lisboa, Portugal .|2 Hospital CUF Infante Santo , Otolaryngology Department, Hospital CUF Infante Santo, Lisboa, Portugal .
authors: João
authors: J
authors: Paço
authors: 3 Deafness Research Group, Biomedicine and Translational Research, BioISI, Faculty of Sciences, University of Lisbon , Lisbon, Portugal .|5 School of Health, Polytechnic Institute of Setubal , Setubal, Portugal .
authors: Helena
authors: H
authors: Caria
mesh_terms: D000293:Adolescent; D000328:Adult; D016022:Case-Control Studies; D002648:Child; D002675:Child, Preschool; D000072259:Connexin 26; D017630:Connexins / Q000235:genetics*; D005260:Female; D014644:Genetic Variation; D014943:Global Health; D006319:Hearing Loss, Sensorineural / Q000453:epidemiology / Q000235:genetics*; D006801:Humans; D008297:Male; D009154:Mutation; D000073136:Sao Tome and Principe / Q000453:epidemiology; D017384:Sequence Deletion; D055815:Young Adult
chemical_list: D017630:Connexins; C000607042:GJB2 protein, human; D000072259:Connexin 26