Introduction: Hearing loss (HL) is the most common sensorineural disorder with the frequency of 1 to 1000 neonates and it's seen in two syndromic and non-syndromic states. Given that the mutations of DFNB1 locus, containing Connexin 26 (Cx26) and 30 (Cx30) genes are the only responsible for 50% non-syndromic HL with autosomal recessive hereditary in different populations, the aim of this study is the screening of the connexin30 gene deletion mutations including Del (GJB6-D13S1830) and Del (GJB6-D13S1854) in HL subjects were negative to mutation in Cx26 gene.
 
Materials & methods: In this descriptive study, 85 unrelated patients (44 males and 41 females) with autosomal recessive hearing loss of Khorasan Razavi province that were negative towards the Cx26 gene mutations, were studied. Genomic DNA was extracted from 1 ml of EDTA anticoagulated peripheral blood by rapid genomic DNA extraction (RGDE) method. For molecular analysis, multiplex PCR and direct sequencing methods were used.
 
Findings: Out of 170 studied chromosomes, none of the Del (GJB6-D13S1830) and Del (GJB6-D13S1854) mutations found in the studied subjects.
 
Discussion & conclusions: Lack of the deletion mutations in the Cx30 gene, indicates the involvement of other genes in causing disease. Thus, it is necessary to study other HL genes in these subjects.