Heterozygous p.Asp50Asn mutation in the GJB2 gene in two Cameroonian patients with keratitis-ichthyosis-deafness (KID) syndrome.

BACKGROUND: Keratitis-Ichthyosis-Deafness (KID) syndrome (OMIM 148210) is a congenital ectodermal defect that consists of an atypical ichthyosiform erythroderma associated with congenital sensorineural deafness. KID appears to be genetically heterogeneous and most cases are caused by GJB2 mutations. Mutations in African patients have been rarely described. CASE PRESENTATION: We report on two unrelated Cameroonian individuals affected with sporadic KID, presenting with the classic phenotypic triad. The two patients were heterozygous for the most frequent p.Asp50Asn mutation. This first report in patients from sub-Saharan African origin supports the hypothesis that the occurrence of KID due to p.Asp50Asn mutation in GJB2 seems not to be population specific. CONCLUSIONS: Our finding has implication in medical genetic practice, specifically in the molecular diagnosis of KID in Africans. These cases also reveal and emphasize the urgent need to develop appropriate policies to care for patients with rare/orphan diseases in Sub-Saharan Africa, as many of these cases become more and more recognizable.

Aetiology of childhood hearing loss in Cameroon (sub-Saharan Africa).

BACKGROUND: Severe hearing loss is a global problem affecting particularly developing countries. There is scarcity of recent published data on the epidemiology of childhood deafness in sub-Saharan Africa. OBJECTIVE: To determine the etiological profile of severe childhood deafness in Cameroon. METHODS: Prospective cross-sectional study of patients with a severe hearing loss that started before the age of 15 years. Detailed family and medical history was obtained; careful clinical, otological and audiological examinations were performed. RESULTS: A total of 582 patients with a severe hearing loss were examined. Prelingual deafness accounted for 75.1% (n = 437), with a mean age at medical diagnosis of 3.3 ± 1.2 years. This late presentation may be explained by limited parental awareness of signs raising suspicion of hearing loss, poor access to health care and the absence of neonatal screening for hearing loss in Cameroon. Identified genetic causes accounted for 14.8% (n = 86), putative environmental causes for 52.6% (n = 306) and unknown causes for 32.6% (n = 190). Amongst Genetic causes, the syndromic hearing loss accounted for 13.1% (n = 12) of cases, the rest being non syndromic (n = 74). Consanguineous families accounted for 5.7% (n = 33) of the whole sample, and 15.1% (n = 13) of genetic cases. No union between deaf parents was observed. CONCLUSION: These data highlight the possible predominance of putative environmental causes of childhood deafness in Cameroon, and emphasize the need for improved policies for prevention of infectious diseases and for neonatal hearing screening. However, further molecular analyses and targeted CT scan investigations are required to more accurately gauge the contribution of genetics etiologies.