title: Genetics of hearing loss in Africans: use of next generation sequencing is the best way forward.
abstract: Hearing loss is the most common communication disorder affecting about 1-7/1000 births worldwide. The most affected areas are developing countries due to extensively poor health care systems. Environmental causes contribute to 50-70% of cases, specifically meningitis in sub-Saharan Africa. The other 30-50% is attributed to genetic factors. Nonsyndromic hearing loss is the most common form of hearing loss accounting for up to 70% of cases. The most common mode of inheritance is autosomal recessive. The most prevalent mutations associated with autosomal recessive nonsyndromic hearing loss (ARNSHL) are found within connexin genes such as GJB2, mostly in people of European and Asian origin. For example, the c.35delG mutation ofGJB2 is found in 70% of ARNSHL patients of European descent is rare in populations of other ethnicities. Other GJB2 mutations have been reported in various populations. The second most common mutations are found in the connexin gene, GJB6, also with a high prevalence in patients of European descent. To date more than 60 genes have been associated with ARNSHL. We previously showed that mutations in GJB2, GJB6 and GJA1 are not significant causes of ARNSHL inpatients from African descents, i.e. Cameroonians and South Africans In order to resolve ARNSHL amongst sub-Saharan African patients, additional genes would need to be explored. Currently at least 60 genes are thought to play a role in ARNSHL thus the current approach using Sanger sequencing would not be appropriate as it would be expensive and time consuming. Next Generation sequencing (NGS) provides the best alternative approach. In this review, we reported on the success of using NGSas observed in various populations and advocate for the use of NGS to resolve cases of ARNSHL in sub-Saharan African populations.
authors.affiliation: Division of Human Genetics, Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa.
authors.forename: Kamogelo
authors.initials: K
authors.lastname: Lebeko
authors.affiliation: Division of Human Genetics, Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa.
authors.forename: Jason
authors.initials: J
authors.lastname: Bosch
authors.affiliation: Faculty of Medicine and Biomedical Sciences, University of Yaoundé I, Yaoundé, Cameroon.
authors.forename: Jean Jacques Nzeale
authors.initials: JJ
authors.lastname: Noubiap
authors.affiliation: Division of Human Genetics, Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa ; Institute for Infectious Disease and Molecular Medicine (IDM), Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa.
authors.forename: Collet
authors.initials: C
authors.lastname: Dandara
authors.affiliation: Division of Human Genetics, Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa.
authors.forename: Ambroise
authors.initials: A
authors.lastname: Wonkam
mesh_terms: D017954:Africa South of the Sahara / Q000453:epidemiology; D044383:Black People / Q000235:genetics*; D000072259:Connexin 26; D000075302:Connexin 30; D017630:Connexins / Q000235:genetics; D034381:Hearing Loss / Q000453:epidemiology* / Q000235:genetics; D059014:High-Throughput Nucleotide Sequencing / Q000379:methods*; D006801:Humans; D009154:Mutation
chemical_list: D000075302:Connexin 30; D017630:Connexins; C000607042:GJB2 protein, human; C491020:GJB6 protein, human; D000072259:Connexin 26
keywords: ARNSHL; OTOScope®; Sub-Saharan Africa; hearing loss; next generation sequencing; targeted exome sequencing; whole exome sequencing