الفهرس Only 14 pages are availabe for public view
 |  | from | 173 |  |  |
| | | from | 173 | | |
Abstract
Abstract
Congenital hearing loss affects 0.1% of children. Recent advances in genetics of deafness show that at least 50% of the congenital cases have a genetic background, with mutations in the Connexin 26 (Cx26) gene being by far the most frequent cause of hearing loss. The present study aimed at detection of connexin 26 protein in buccal smears obtained from hearing impairment children and healthy control cases. Moreover, auditory brain stem response and pure tone audiometry are studied.
The present study included 20 cases from seven families affected by congenital sensorineural hearing impairment. Ten subjects with normal hearing matched for age and sex representing control group. They were referred to the clinic of children with special needs, National Research Center. Cases >4 years old were subjected to pure tone audiometry and cases ?4 years old were subjected to auditory brain stem response. Out of the affected cases, ten patients from two families with known mutation in connexin 26 gene, affecting c-terminus of connexin 26 protein (35delG) mutation were selected. Meanwhile, the other 10 patients had other mutations rather than 35delG with unknown effect on connexin 26 protein. Immunofluorescent studies for detection of connexin 26 protein were applied to the cases with 35 delG mutation (10 cases) and compared to those with other mutations and control subjects.
Audiological analysis of the studied cases showed that, severe hearing loss (HL) in 50 % of cases, 20% of cases had moderately severe HL, 20% of cases had moderate HL while 10% of cases had profound hearing loss and non of the studied cases had mild HL. These results indicate that severe HL is the most common type of deafness.
Regarding detection of connexin 26 protein, absence of connexin 26 immunofluorescent signals in 10 patients with (35 delG) leading to a known effect on the c-terminus of connexin 26 protein. On the other hand, with mutations other than 35del G, connexin 26 protein was detected in 10 cases.
Image processing analysis software (Array Vision MCID) was used to quantify the connexin immunofluorescent signals, to compare the test slides with that of control slides. We verified that connexin signals are highly variable.
We concluded that detection of connexin 26 protein in buccal smear may help in the identification of mutations in connexin 26 gene specifically 35delG mutations. This will help in rapid diagnosis and management of cases with congenital sensorineural hearing loss and subsequently proper counseling.