2013, Number 2
Importance of the diagnosis of protein connexin 26 mutations in the integral management of nonsyndromic congenital deafness
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ABSTRACTBackground. Congenital deafness is a public health problem affecting 2-3/1000 newborns in Mexico. Neonatal audiologic screening allows early detection with important implications for the functional prognosis. About 70% of cases of congenital deafness are associated with a genetic etiology with an autosomal recessive pattern of inheritance. Most cases are caused by mutations in the GJB2 gene, which codifies connexin 26. The three most commonly reported mutations in this gene are c.35delG, c.167delT and c.235delC.
Methods. After obtaining informed consent, DNA was extracted from a blood sample, and the three previously mentioned mutations were searched for using PCR-RFLP or PCR followed by sequencing.
Results. Molecular analysis was carried out in 11 patients. In five of these patients, a change in sequence was observed. In none of the patients were c.167delT and c.235delC mutations found. One patient was homozygous for c.35delG and another patient was heterozygous for c.35insG, which is a mutation not previously reported. A third patient was heterozygous for c.34G›T. Two additional patients had the c.79G›A (p.V27I) polymorphism.
Conclusions. Frequency of the three mutations analyzed was lower compared to other populations. Five sequence changes were observed, two polymorphisms and three mutations, one of them novel. This study also demonstrates the relevance of early diagnosis and multidisciplinary management and the importance of determining the genetic basis of this disease in pediatric patients with congenital deafness.
Arenas-Sordo M, Hernández-Zamora E, Gutiérrez-Tinajero D, Murphy-Ruiz P, Leyva-Juárez X, Huesca-Hernández F, et al. Mutaciones de los genes GJB2 y GJB6 en pacientes con hipoacusia bilateral prelinguística del INR. Memorias del III Congreso Internacional de Investigación en Rehabilitación, Ciudad de México. Noviembre, 2012. Disponible en: http://www.inr.gob.mx/Descargas/ciir/memorias3erCongreso.pdf
Martínez-Saucedo M, González-Huerta LM, Berruecos P, Rivera-Vega MR, Cuevas-Covarrubias SA. Análisis de la deleción del gen GJB6 en pacientes heterocigotos para el gen GJB2 con hipoacusia neurosensorial no sindrómica en una muestra de población mexicana. XXXVII Congreso Nacional de Genética Humana, Guadalajara, Jalisco. Noviembre, 2012.