West African Centre for Cell Biology of Infectious Pathogens (WACCBIP), University of Ghana, P. O. Box LG 54 Accra, Ghana.
Division of Human Genetics, Faculty of Health Sciences, University of Cape Town, 7925 Cape Town, South Africa.
Genes (Basel). 2020 Jan 27;11(2):132. doi: 10.3390/genes11020132.
In Ghana, gap-junction protein β 2 () variants account for about 25.9% of familial hearing impairment (HI) cases. The -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 -p.Arg143Trp variant. All hearing-impaired participants from 7/8 families were homozygous positive for the -p.Arg143Trp mutation using the NciIRFLP 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 -p.Arg143Trp NciIRFLP 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 p.Arg143Trp NciIRFLP-based diagnostic test had a high sensitivity for genotyping the most common 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.
在加纳，缝隙连接蛋白 β2 () 变体约占家族性听力障碍 (HI) 病例的 25.9%。-p.Arg143Trp (NM_004004.6:c.427C>T/OMIM: 121011.0009/rs80338948) 变体仍然是与加纳先天性 HI 相关的最常见变体，但尚未在临床实践中进行研究。因此，我们试图设计一种快速且具有成本效益的测试来检测这种变体。我们从 8 个分离常染色体隐性非综合征 HI 的家族中抽取了 20 名听力受损和 10 名正常听力的家庭成员进行采样。此外，还选择了 111 名孤立性 HI 无关个体和 50 名正常听力对照组参与者。使用优化并通过 Sanger 测序验证的内切酶 NciI 设计了一种限制性片段长度多态性 (RFLP) 测试，用于快速基因分型常见的-p.Arg143Trp 变体。使用 NciIRFLP 测试，8 个家族中的 7/7 个家庭的所有听力受损参与者均为-p.Arg143Trp 突变纯合阳性，该结果通过 Sanger 测序得到了证实。对先前通过 Sanger 测序的 111 名孤立性非综合征 HI 个体进行调查发现，-p.Arg143Trp NciIRFLP 测试的灵敏度为 100%。所有 50 名听力正常的对照组均未发现该变体。尽管该测试非常有价值，但它并非 100%特异，因为它无法区分限制酶识别位点处的其他突变。基于 p.Arg143Trp NciIRFLP 的诊断测试对加纳人群中最常见的致病性和起源变体 (p.Arg143Trp) 的基因分型具有很高的灵敏度。我们建议采用并实施该测试用于听力障碍遗传临床研究，以补充加纳的新生儿听力筛查计划。本研究是在非洲加强遗传医学的实际案例。
