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Open AccessArticle

Enhancing Genetic Medicine: Rapid and Cost-Effective Molecular Diagnosis for a GJB2 Founder Mutation for Hearing Impairment in Ghana

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West African Centre for Cell Biology of Infectious Pathogens (WACCBIP), University of Ghana, P. O. Box LG 54 Accra, Ghana
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Division of Human Genetics, Faculty of Health Sciences, University of Cape Town, 7925 Cape Town, South Africa
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Bacteriology Department, Noguchi Memorial Institute for Medical Research, University of Ghana, P.O. Box LG 581 Accra, Ghana
4
Department of Eye Ear Nose & Throat, School of Medical Sciences, Kwame Nkrumah University of Science and Technology, Private Mail Bag Kumasi, Ghana
*
Author to whom correspondence should be addressed.
Genes 2020, 11(2), 132; https://doi.org/10.3390/genes11020132
Received: 21 December 2019 / Revised: 21 January 2020 / Accepted: 22 January 2020 / Published: 27 January 2020
(This article belongs to the Special Issue Genetic Epidemiology of Deafness)
In Ghana, gap-junction protein β 2 (GJB2) variants account for about 25.9% of familial hearing impairment (HI) cases. The GJB2-p.Arg143Trp (NM_004004.6:c.427C>T/OMIM: 121011.0009/rs80338948) variant remains the most frequent variant associated with congenital HI in Ghana, but has not yet been investigated in clinical practice. We therefore sought to design a rapid and cost-effective test to detect this variant. We sampled 20 hearing-impaired and 10 normal hearing family members from 8 families segregating autosomal recessive non syndromic HI. In addition, a total of 111 unrelated isolated individuals with HI were selected, as well as 50 normal hearing control participants. A restriction fragment length polymorphism (RFLP) test was designed, using the restriction enzyme NciI optimized and validated with Sanger sequencing, for rapid genotyping of the common GJB2-p.Arg143Trp variant. All hearing-impaired participants from 7/8 families were homozygous positive for the GJB2-p.Arg143Trp mutation using the NciI-RFLP test, which was confirmed with Sanger sequencing. The investigation of 111 individuals with isolated non-syndromic HI that were previously Sanger sequenced found that the sensitivity of the GJB2-p.Arg143Trp NciI-RFLP testing was 100%. All the 50 control subjects with normal hearing were found to be negative for the variant. Although the test is extremely valuable, it is not 100% specific because it cannot differentiate between other mutations at the recognition site of the restriction enzyme. The GJB2-p.Arg143Trp NciI-RFLP-based diagnostic test had a high sensitivity for genotyping the most common GJB2 pathogenic and founder variant (p.Arg143Trp) within the Ghanaian populations. We recommend the adoption and implementation of this test for hearing impairment genetic clinical investigations to complement the newborn hearing screening program in Ghana. The present study is a practical case scenario of enhancing genetic medicine in Africa.
Keywords: hearing impairment; GJB2-p.R143W; NciI-RFLP; rapid diagnostic test; Ghana hearing impairment; GJB2-p.R143W; NciI-RFLP; rapid diagnostic test; Ghana
MDPI and ACS Style

Adadey, S.M.; Tingang Wonkam, E.; Twumasi Aboagye, E.; Quansah, D.; Asante-Poku, A.; Quaye, O.; Amedofu, G.K.; Awandare, G.A.; Wonkam, A. Enhancing Genetic Medicine: Rapid and Cost-Effective Molecular Diagnosis for a GJB2 Founder Mutation for Hearing Impairment in Ghana. Genes 2020, 11, 132.

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