Abstract
Congenital Sensorineural Non syndromic hearing loss involves genetic mutations and acquired environmental factors. In both of these cases inner ear function is disturbed resulting in dysfunction of inner ear and auditory system. New advances were under progress for the identification of deafness causing genes during last decade. Infections like meningitis, measles and cytomegalovirus infection were also known to be involved in postnatal cases of childhood deafness. One in 800-1000 children have hearing impairment since birth and it may affect the people as they age. More than 50% cases of childhood deafness have defect in a single gene. Genetic factors and intrauterine dysplasia caused congenital hearing loss. Hearing loss might be non-syndromic or syndromic and may existing as autosomal recessive, autosomal dominant or sex linked. The first gene to be found to affect non-syndromic autosomal recessive hearing loss was gap junction protein beta 2(GJB2). Connexin 26 protein is encoded by gap protein beta 2 and connexion 26 functions to maintain inner ear homeostasis. Another gene involved in hearing loss is LHFPL that encodes lipoma HMGIC fusion partner like 1 protein. Mutations in LHFPL also result in genetic deafness in humans. This work was designed to recognize the causative mutations and variation analysis in GJB2 and LHFPL genes in affected families of Bahawalnagar region. Families (09) with 2 or more affected members of deafness were identified and have been registered after informed consent. Total 36 samples from all nine families were selected and sent for sequencing that showed only four families carried variations, among total 36 samples at six different positions. All the variations were observed by comparing with bio edit file of sequencing result with primer sequence. This study found that GJB2 gene exon 1 have no variations in all subjects on the other hand, Exon 2 showed 2 variations in one family at c899mis A and c901 A>G. this suggested that exon 1 is less peculiar gene in causing genetic hearing loss in this region. Along with this, Another heterozygous base chain observed at c561 G>A( GAG to GAA) with no change in amino acid (synonyms). According to this study out of 9 families we found variations in GJB2 genes in only 2 families which accounts for 22.22% in this region. For more advanced and widespread analysis of congenital causes of childhood deafness genetic testing, prenatal analysis, family history records and counselling to avoid first cousin marriages is suggested.
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