نجمه فتاحی

Hearing loss is a most common sensory deficit in humans. The hearing loss may be conductive, sensorineural, or mixed (syndromic or nonsyndromic), prelingual or postlingual. Due to the complexity of the hearing mechanism, it is not surprising that several hundred genes might be involved in causing hereditary hearing loss. So far 152 loci have been identified which are associated with the most common type of hearing loss. This study aimed to analyze genetic linkage of DFNB7/11 locus in families with autosomal recessive nonsyndromic hearing loss from Hamedan province.
In this descriptive laboratory study, 24 families from Hamedan province with autosomal recessive nonsyndromic hearing loss were examined. Selected families in this study had consanguinity and they were negative for GJB2 gene mutations. Linkage analysis was performed by 7 markers (STR) for DFNB7/11 locus.
After examining different families, one family of the 24 families (4.16%) showed linkage to the DFNB7/11 locus, but in examining different exons and promoter of TMC1 gene, no mutation was found. Lack of TMC1gene mutations in mentioned familyy suggests mutations exist in noncoding regions of TMC1 genes or new gene exists in this locus. SLINK value and LOD score of this family was 1.45 and 0.54 respectively.
Based on the results of this study, DFNB7/11 locus may not have important role in causing hearing loss of population studied, but further studies are necessary to determine more precisely the role of this locus in hearing loss in Iranian population.

Sensorineural hearing loss (SNHL) is the most common sensory disorder and 1 in every 500-1000 newborns is affected. Non-syndromic SNHL accounts for 70% of hereditary hearing loss and 80% of SNHL cases have an autosomal recessive mode of inheritance (ARNSHL). The Purpose of the recent study is genetic linkage analysis to determine the prevalence of DFNB40 and DFNB48 loci in studying families with ARNSHL from the western provinces of Iran.
In this study, 60 families from 3 provinces of Iran involving Hamedan, Kohgiluyeh and Boyer-Ahmad and Chaharmahal and Bakhtiari with autosomal recessive non syndromic hearing loss were examined. The selected families in this study were consanguineous and had at least two patients. They also were negative for GJB2 mutations. Linkage analysis was performed by using 6 markers short tandem repeat (STR) for the DFNB40 locus and 7 markers STR for the DFNB48 locus.
Findings: After examining different families, it was revealed that none of them showed linkage to the DFNB40 and DFNB48 loci.
The recent study suggests that DFNB40 and DFNB48 loci might not play an important role in causing hearing loss in the mentioned provinces. However, further studies are necessary to determine more precisely the role of these loci in the Iranian population.

Bilateral sensorineural hearing loss is one of the most frequent congenital defects, and it has the prevalence of one in thousand among the infants. The most cases of hearing impairment are nonsyndromic and about 80 percent of patients with sensorineural HE show authosomal recessive pattern. ARSNL is a very heterogenic defect for over 70 loci and 50 genes have been found. In this study, in order to prove the prevalence of DFNB59 mutations, we examined DFNB59 mutations in 54 families from 3 provinces of Iran including Hamedan, Kohgiluye& Boveir Ahmad and Chaharmahal Bakhtiari. The gene (PJVK) in this locus encodes Pejvakin protein (PJVK) and causes nerve stimulation to conduct. Selected families in this study have consanguinity and at least have two patients with the defect; they also are negative in having the GJB2 mutations. Six markers were selected for this locus and linkage analysis was performed. However, after examining different families, it was revealed that none of them had linkage to the DFNB59 locus. Therefore, this study suggests that that Pejvakin mutations might not play an important role in causing hearing loss in these provinces.

Hearing loss is a sensorineural impairment and is one of the most widespread congenital impairments with a prevalence of one in thousand among children. Studies have shown that 50 percent of congenital hearing loss have genetic causes and the remaining 50 percent are due to environment and unknown reasons; in addition, it is noted that this impairment is very heterogeneous. Almost 70 percent of cases are nonsyndromic with hearing loss presenting as the only impairment. About 80 percent of this type of hearing loss is inherited in recessive manner (ARNSHL). In this study, we determined the role of DFNB63 locus in a series of families in two western provinces of Iran. In this descriptive-laboratory study, to determine the prevalence of DFNB63 mutations in western provinces of Iran, we studied 150 individuals from 30 families in Hamadan and Kohgiluyeh and Boyer-Ahmad provinces. The selected families in this study were consanguineous, had at least 2 patients, and were negative for GJB2 mutations. Linkage analysis was performed using six appropriate short tandem repeats (STR) markers. With linkage analysis of selected families, no family was shown to be linked to the DFNB63 locus. It was shown that the LRTOMT mutations played no role in causing hearing loss in the studied families. The present study suggests that LRTOMT mutations may not be clinically important in causing autosomal recessive nonsyndromic hearing loss in the investigated provinces.