Confirmation of diagnosis in Romanian children with DFNB1 related hearing loss

Cristina Dragomir, Adriana Stan Stan, Dragos Tiberiu Stefanescu, Lorand Savu, Codrut Sarafoleanu, Adrian Toma, Emilia Severin

Carol Davila, University of Medicine and Pharmacy, 37 Dionisie Lupu St, Bucharest, Romania.
Davila, University of Medicine and Pharmacy, 37 Dionisie Lupu St, Bucharest, Romania.
Genetic Lab, 43B Ghencea Avenue, Bucharest, Romania.
Panait Sirbu Hospital, Calea Giulesti, Bucharest, Romania.

DOI: 10.4236/ajmb.2013.34029                

Abstract

DFNB1 locus has been linked to a nonsyndromic “invisible disability” called congenital sensorineural hearing loss and deafness. Mutations of GJB2 and GJB6 genes are associated with deafness at the DFNB1 locus. The diagnosis of DFNB1 is made with molecular genetic testing. DNA-based testing can be used both prenatally and postnatally. Purpose: to get evidence for implementation of newborn hearing screening programs at national level; to use the molecular testing of children at risk for confirmation of diagnosis and early intervention. OAEs and ABR were performed for 4303 newborns. Audiologic evaluation of 38 children suspected of having hearing loss was performed too. Physical examinations and family history were used to get information about congenital deafness. DNA from blood samples was isolated, and two PCR multiplex assays were developed to detect DFNB1 mutations. Only 23 newborns were screened positive. Newborns were referred to audiologic evaluation, genetic counseling and testing for the etiologic diagnosis. Physical examination revealed no other abnormal findings. GJB2 mutations were detected in 36.03% of patients, and all of them have 35delG mutation. None of them was found to have GJB6 mutations. Our results suggested that molecular testing was an accurate method of early determining cause of congenital hearing loss and helped us to exclude GJB6 gene from the routine hearing screening protocol.

Keywords

DFNB1; Molecular Genetic Testing; GJB2; GJB6

Conflicts of Interest

The authors declare no conflicts of interest.

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