Rare non-syndromic prelingual hearing disorders in a southeast European patient collective

Introduction 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. At this juncture 170 gene loci can be associated with this type of hearing disorder, in total there are 127 genes identified for the number of dominant and recessive inheritance.

Genetic changes in the DFNB1 gene locus, in which the genes GJB2 gene (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 in addition the GJB2 and GJB6 genes are involved in prelingual hearing disorders.

Methods To date 120 patients have been included in our study who have been diagnosed with severe non-syndromic 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.

Results First of all, the genes MPZL2 and CABP2 were analyzed in this patient group followed by genes TPRN, SPNS2 and CLDN9. By DNA sequencing, 1 novel mutations, 6 unknown polymorphisms and 8 known alterations that are already cataloged in the databases of international sequencing projects have been detected so far.

Conclusions In the investigated patients mutations and previously unknown polymorphisms were occasionally characterized in the genes MPZL2, CABP2 as well as TPRN, SPNS2 and CLDN9, 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.

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Artikel online veröffentlicht:
10. Juni 2020