Clinical research Aetiology of childhood hearing loss in Cameroon (sub-Saharan Africa) Ambroise Wonkam a, b, * , Jean Jacques N. Noubiap b , François Djomou b , Karen Fieggen a , Richard Njock b , Geneviève Bengono Toure b a Division of Human Genetics, Department of Clinical Laboratory Sciences, Faculty of Health Sciences, University of Cape Town, South Africa b Faculty of Medicine and Biomedical Sciences, University of Yaoundé I, Yaoundé, Cameroon article info Article history: Received 10 January 2012 Accepted 30 September 2012 Available online 17 October 2012 Keywords: Prelingual deafness Syndromic deafness Non-syndromic deafness Cameroon Sub-Saharan Africa abstract 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 audi- ological examinations were performed. Results: A total of 582 patients with a severe hearing loss were examined. Prelingual deafness accounted for 75.1% (n ¼ 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 ¼ 86), putative environmental causes for 52.6% (n ¼ 306) and unknown causes for 32.6% (n ¼ 190). Amongst Genetic causes, the syndromic hearing loss accounted for 13.1% (n ¼ 12) of cases, the rest being non syndromic (n ¼ 74). Consanguineous families accounted for 5.7% (n ¼ 33) of the whole sample, and 15.1% (n ¼ 13) of genetic cases. No union between deaf parents was observed. Conclusion: These data highlight the possible predominance of putative environmental causes of child- hood 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. Ó 2012 Elsevier Masson SAS. All rights reserved. 1. Introduction Severe hearing loss is the most frequent sensorineural disorder in children, affecting about one in 500 neonates worldwide [1,2]. Although it is a global problem, almost two-thirds of individuals with hearing impairment live in developing countries [3]. The etiological profile of childhood deafness varies considerably from one region to another. In industrialized countries, genetic causes are now responsible for more than 50% of cases [4]. In developing countries there is dearth of recent published data on the epide- miology of childhood deafness, but available data reported that environmental causes are predominant, with almost 30% of deaf- ness still of unknown origin [5e9]. With 20 million inhabitants, Cameroon is frequently referred to as “Africa in miniature” because of its central location on the continent and its many geographical and cultural attributes and human population diversity (there are more than 200 distinct local languages in the country). The country spans two main geographical zones of almost equal size: the equatorial rain forest in the south and the tropical savanna and the Sahel region in the north. The health-care system of the country is organized into the public, private and traditional sectors [10]. There is no universal medical insurance coverage in Cameroon; typically, CT scan that is necessary for investigating causes and associated malformation in some patients with hearing loss, is available only in the two main cities in Cameroon (Douala and Yaoundé), and unaffordable for the majority of patients. Like most low and middle-income countries, Cameroon is facing an epidemiologic transition with an increasing and recog- nized burden of chronic non-communicable diseases, some of which are of genetic origin A medical genetic service was inaugu- rated in Cameroon in January 2007, but molecular diagnosis is not yet available locally or in neighbouring countries. With the ability to extract DNA locally, prenatal genetic diagnosis for sickle cell anaemia and aneuploïdies, as well as some occasional molecular analysis, is possible only in collaboration with European centres [11]. * Corresponding author. Division of Human Genetics, Faculty of Health Sciences, University of Cape Town, Anzio Road-7925, Observatory, Cape Town, South Africa. Tel.: þ27 21 406 6307; fax: þ27 21 406 6826. E-mail address: Ambroise.wonkam@uct.ac.za (A. Wonkam). Contents lists available at SciVerse ScienceDirect European Journal of Medical Genetics journal homepage: http://www.elsevier.com/locate/ejmg 1769-7212/$ e see front matter Ó 2012 Elsevier Masson SAS. All rights reserved. http://dx.doi.org/10.1016/j.ejmg.2012.09.010 European Journal of Medical Genetics 56 (2013) 20e25