Knowledge and attitudes concerning medical genetics amongst physicians and medical students in Cameroon (sub-Saharan Africa).

PURPOSE: Little is known about physician's knowledge of, and attitudes toward genetics in sub-Saharan Africa. METHODS: Survey of 101 pre-clinical, 95 clinical medical students, and 110 physicians, in Cameroon. RESULTS: The awareness of DNA diagnosis was poor: 0, 2.2, and 1.2%, respectively, for sickle cell anemia. The majority of the respondents considered genetic counseling as indispensable (97.6, 98.9 and 100%); and prenatal diagnosis as acceptable. The acceptance of medical abortion increased with the level of medical education (62.6, 74.7 and 90.7%). Sickle cell anemia was considered as a "serious disease" by a greater majority of respondents than Down syndrome (P < 0.001). But, in all three groups, the acceptance of termination of affected pregnancy "if the respondent's own child was affected" was lower for sickle cell anemia than Down syndrome (22.4 versus 40.2%, 10.8 versus 29.3% and 36.1 versus 70.4%). CONCLUSIONS: The data suggest a poor knowledge of genetic tests among medical students and physicians. This cohort appears to accept the principles of medical genetics. Our data emphasized a need to introduce genetics and to develop research on its ethical and social implications in Cameroon.     

Perspective on noise induced hearing loss in Africa

Noise-induced hearing loss (NIHL) occurs everyday in both occupational and non-occupational settings in developed and developing countries. The good news is that NIHL is preventable through industrial control laws and programmes. In this paper, an attempt has been made to discuss the problem of NIHL, its relevance to African countries and strategies for its prevention.     

Rheopheresis for sudden hearing loss (SHL)

Rheopheresis has met an increasing interest and application in different disease conditions affecting microcirculation. Its last applications are for the management of Macular and Cochlear disorders. The sudden hearing loss syndrome is a condition that affects 20 out of 100,000 persons per year, reduces the patient's social interaction and quality of life. It is associated with vascular and coagulation risk factors and it is considered as a result of local hypoperfusion secondary both to inflammatory and dysimmune conditions determining inadequate NO release and endothelial dysfunction. Rheopheresis treatment is a new approach which brings to satisfactory clinical results. Cascade filtration, heparin induced lipid precipitation and conventional plasma exchange are equally effective, and only 2 sessions are required for producing long lasting benefits. Our experience is with 60 patients, 90% of which getting from partial to complete recovery after treatment as measured by pure tone audiometry.     

Scorpion stings in sub-Saharan Africa

Scorpionism in Sub-Saharan Africa is a poorly known problem but regarded as a public health preoccupation in several countries, especially Niger. The lack of knowledge of this question is due to non-existent information concerning mainly the composition of the scorpion fauna in Sub-Saharan areas, the distribution and density of dangerous species and the frequency and severity of scorpion stings in the Sub-Saharan areas. Until now, only the presence of Leiurus quinquestriatus and its involvement in fatal accidents have been attested to. In many areas, the presence of other classically dangerous species has not been confirmed, nor the dangerous potential of certain species belonging for example to the genera Androctonus. Buthus or Hottentota. The efficacy of prevention, treatment and scorpion control depend necessarily on further study of the fauna and medical investigations. Such studies are entirely feasible.     

Allergies and parasitoses in sub-Saharan Africa

There has been nearly an epidemic rise in allergic disease throughout the world. However, this significant increase in the prevalence of allergic diseases has not been reported on the African continent. There are many factors which have been offered to explain these differences, including nutrition, environmental factors and genetic contributions. In addition, these differences in allergic disease incidents have often been discussed in terms of the hygiene parasitoses and allergic diseases and illustrate their interactions with socioeconomic, cultural, and sanitary realities. The data is particularly applicable to Senegal but can be extrapolated to other regions throughout the world and the results have implications for the induction of allergic disease in both western and Third World countries.     

Genomic analysis of childhood hearing loss in the Yoruba population of Nigeria

Although variant alleles of hundreds of genes are associated with sensorineural deafness in children, the genes and alleles involved remain largely unknown in the Sub-Saharan regions of Africa. We ascertained 56 small families mainly of Yoruba ethno-lingual ancestry in or near Ibadan, Nigeria, that had at least one individual with nonsyndromic, severe-to-profound, prelingual-onset, bilateral hearing loss not attributed to nongenetic factors. We performed a combination of exome and Sanger sequencing analyses to evaluate both nuclear and mitochondrial genomes. No biallelic pathogenic variants were identified in GJB2, a common cause of deafness in many populations. Potential causative variants were identified in genes associated with nonsyndromic hearing loss (CIB2, COL11A1, ILDR1, MYO15A, TMPRSS3, and WFS1), nonsyndromic hearing loss or Usher syndrome (CDH23, MYO7A, PCDH15, and USH2A), and other syndromic forms of hearing loss (CHD7, OPA1, and SPTLC1). Several rare mitochondrial variants, including m.1555A>G, were detected in the gene MT-RNR1 but not in control Yoruba samples. Overall, 20 (33%) of 60 independent cases of hearing loss in this cohort of families were associated with likely causal variants in genes reported to underlie deafness in other populations. None of these likely causal variants were present in more than one family, most were detected as compound heterozygotes, and 77% had not been previously associated with hearing loss. These results indicate an unusually high level of genetic heterogeneity of hearing loss in Ibadan, Nigeria and point to challenges for molecular genetic screening, counseling, and early intervention in this population.Subject terms: Genetics research, Medical genomics     

Human immunodeficiency virus (HIV) and malaria interaction in sub-Saharan Africa: the collision of two Titans

HIV and malaria are among the leading causes of morbidity and mortality in sub-Saharan Africa, home to 10% of the world's population. An association between HIV and malaria is expected in theory, however, there is conflicting evidence regarding the impact of HIV infection on parasite loads. HIV-associated immunosuppression contributes to more frequent and more severe malaria and reduced efficacy of antimalarials in pregnant women and adults. These effects are modified by the endemicity and stability of malaria transmission. Co-infection with malaria and HIV in pregnant women is associated with anemia, low birth weight, and increased risk of infant mortality to a greater extent than infection with either disease alone. Studies investigating the impact of placental malaria on mother-to-child HIV-1 transmission continue to show conflicting results. This article attempts to review the pertinent information available about the interaction between HIV and malaria and information about chemoprophylaxis and treatment issues. Although much has been published in the last 10 years regarding the interaction of HIV and malaria in sub-Saharan Africa, we still need more information so as to understand the issues that will help us develop effective programs.     

Frequency of the branchio-oto-renal (BOR) syndrome in children with profound hearing loss

Nineteen of 421 white children in Montreal schools for the deaf had preauricular pits. The branchio-oto-renal (BOR syndrome was identified in four of the nine families who agreed to family investigation, including audiograms and intra-venous pyelograms (IVPs), and may have been present in several others. The penetrance of this autosomal dominant syndrome appears to be high. It is estimated that severe renal dysplasia occurs in about 6% of heterozygotes. The presence of a preauricular pit at birth suggests that the child has at least one chance in 200 of severe hearing loss, and this warrants a careful family history, as well as alertness for any signs of hearing impairment. Offspring of affected individuals are eligible for prenatal diagnosis of renal dysplasia.     

The search of a genetic basis for noise-induced hearing loss (NIHL)

Background and aim: Knowledge about the genetic factors responsible for noise-induced hearing loss (NIHL) is still limited. This study investigated whether genetic factors are associated or not to susceptibility to NIHL.

Subjects and methods: The family history and genotypes were studied for candidate genes in 107 individuals with NIHL, 44 with other causes of hearing impairment and 104 controls. Mutations frequently found among deaf individuals were investigated (35delG, 167delT in GJB2, Δ_rm;(GJB6- D13S1830), Δ_rm;(GJB6- D13S1854) in GJB6 and A1555G in MT-RNR1 genes); allelic and genotypic frequencies were also determined at the SNP rs877098 in DFNB1, of deletions of GSTM1 and GSTT1 and sequence variants in both MTRNR1 and MTTS1 genes, as well as mitochondrial haplogroups.

Results: When those with NIHL were compared with the control group, a significant increase was detected in the number of relatives affected by hearing impairment, of the genotype corresponding to the presence of both GSTM1 and GSTT1 enzymes and of cases with mitochondrial haplogroup L1.

Conclusion: The findings suggest effects of familial history of hearing loss, of GSTT1 and GSTM1 enzymes and of mitochondrial haplogroup L1 on the risk of NIHL. This study also described novel sequence variants of MTRNR1 and MTTS1 genes.     

Tinnitus and hearing loss in hamsters (Mesocricetus auratus) exposed to loud sound

Hamsters were trained to go left and right to sounds on their left and right sides, respectively. Silent trials were occasionally given in which no sound was presented. Hamsters exposed to a loud 2- or 10-kHz tone in 1 ear often shifted their responding on the silent trials to the side of the exposed ear, suggesting that they perceived a sound in that ear (i.e., tinnitus). The degree of tinnitus was related to the degree of the accompanying hearing loss (estimated by the auditory brainstem response). However, a conductive hearing loss (plugging 1 ear) did not cause a hamster to test positive for tinnitus. Tinnitus could be demonstrated within minutes following tone exposure, indicating an immediate onset, as occurs in humans.