Molecular genetic analysis of rare non-syndromal prelingual hearing disorders in a Romanian patient collective
23 April 2019 (online)
About 1 – 3/1000 newborns are affected by a profound hearing disorder at birth or in the first two years of life. About 60% of these cases are due to genetic causes. To date, 181 gene loci and 116 genes have been identified for this type of hearing impairment. Genetic changes in the DFNB1 gene locus, in which the genes GJB2 (connexin-26) and GJB6 (connexin-30) are localized represent the main cause of prelingual non-syndromal hearing disorders. The aim is to clarify which other genes in unclear etiology genes are involved in prelingual hearing disorders.
To date 120 patients have been included in our study who have been diagnosed with severe non-syndromal hearing impairment in their first two years of life and who have been shown to show no change in the DFNB1 gene locus or GJB2 and GJB6 gene, respectively. The detection of genetic alterations was carried out by bi-directional sequencing of the coding exons, as well as the intron transitions.
First of all, the genes GRXCR1 and ESRRB were analyzed in this patient group followed by genes TMIE, GIPC, CLDN14, CABP2 and LHFPL5. By DNA sequencing, 2 novel mutations, 5 unknown polymorphisms and 10 known alterations that are already cataloged in the databases of international sequencing projects have been detected so far.
In the investigated patients mutations and previously unknown polymorphisms were occasionally characterized in the genes GRXCR1, ESRRB as well as TMIE, GIPC and LHFPL5, however, an accumulation of changes is not available, therefore, further investigations are required to better characterize the etiology of prelingual hearing disorders to be able to.