Clinical study and genetics of non syndromic congenital deafness

Hearing impairment affects 1/1000 infants. Congenital deafness is inherited or apparently sporadic. DFNB1 on chromosome 13 is a major locus for recessive deafness in about 80% of Mediterranean families and the connexin-26 gene gap junction protein b2 [GJB2] is mutated in DFNB1 families. We acquired DNA samples from 38 families of Moroccan children with recessive non-syndromic deafness and 95 unrelated participants with apparently sporadic congenital deafness. Therefore, we analysed the coding region of the GJB2 gene for mutations. Findings: 31.5% of participants with recessive deafness and 21.5% of sporadic deafness had mutations in the GJB2 gene. The 35delG mutation represented 24.1% of GJB2 mutations. GJB2 gene mutation is a major cause of inherited congenital deafness. 35delG mutation is the most common mutation for inherited congenital deafness. This study shows that 35delG mutation prevalence is important in Morocco with a prevalence of 31.5%, while it is inexistent in Asian population, and very rare in Africa [2.2%]. Such prevalence disparity may reflect an anthropological history of human travels. So, 35delG mutation has a Mediterranean origin. In conclusion, the mutation in the connexion-26 GJB2 gene is the most common cause of non syndromic autosomal recessive deafness in Morocco. More studies are needed to confirm these findings

[Interests of the assessment of non A non B hepatitis's indirects markers anti HBc and ALAT]

This is a study of the incidence of anti HBc and the seric rate of ALAT transaminases in the blood donors. The presence of the anti HBc has been searched by the ELISA technic in 4104 donors. Anti HBc was detected in 1358 [33,1%]. The HBs antigen has been searched to by ELISA technic and detected in 209 [5,1%] of the donors screened. This both markers, have been found in 134 [3,3%] donors. The seric rate of ALAT has been determined on 2627 serums by colorimetric method. 87[3,4%] donors had ALAT levels above 40 UI/I. The simultaneous study of presence of the anti-HBc and seric rate of ALAT has been realesed on 1754 serums. 25 [1,4%] of these donors have avered to be positive anti-HBc with raised ALAT. The HIV serology was negative for all the samples tested in hepatitis B virus serology. These results high light the importance of infection by hepatitis B virus in Morocco. Immunization measures against this virus would be desirables. however, for such a strategy, economic and epidemiological values need to be taken into consideration