Association of polymorphisms at LDLR locus with coronary artery disease independently from lipid profile

Coronary artery disease (CAD) is the leading cause of mortality in many parts of the world. Genome-wide association studies (GWAS) have identified several genetic variants associated with CAD in Low-density lipoprotein receptor (LDLR) locus. This study was evaluated the possible association of genetic markers at LDLR locus with CAD irrespective to lipid profile and as well as the association of these SNPs with severity of CAD in Iranian population. Sequencing of 2 exons in LDLR gene (Exon 2, 12) and part of intron 30 of SMARCA4 gene include rs1122608, was performed in 170 Iranian patients angiographically confirmed CAD and 104 healthy controls by direct sequencing. Sullivan's scoring system was used for determining the severity of CAD in cases. Our results showed that homozygote genotypes of rs1122608 (P<0.0001), rs4300767 (P<0.005) and rs10417578 (p<0.007) SNPs have strong protective effects on the CAD. In addition, we found that rs1122608 (GT or TT) was at higher risk of three vessel involvement compared to single vessels affecting (P=0.01).

Optimizing A Lipocomplex-Based Gene Transfer Method into HeLa Cell Line

One of the most significant steps in gene expression studies is transferring genes into cell cultures. Despite there are different methods for gene delivery such as viral and non-viral producers, some cationic lipid reagents have recently developed to transfect into mam- malian cell lines. The main aim of this study was optimizing and improving lipocomplex based transient transfection procedures into HeLa cell line which is being used widely as a typical cell in biological studies. This study was an experimental research. In this work, pCMV β-Gal DNA plasmid was used as a reporter DNA for determining the rate of gene transfection into HeLa cells. To accomplish the highest gene delivery into HeLa cells, optimizing experiments were car- ried out in different volumes of FuGENE-HD, Lipofectamine(TM)2000 and X-tremeGENE. Also, we investigated tranasfection efficiency in presence of various cell densities of HeLa cells. Then, transfection efficiency and cell toxicity were measured by beta gal staining and trypan blue methods, respectively. Using FuGENE-HD in volume of 4µl along with 10(5) HeLa cells, transfection efficiency was higher (43.66 ± 1.52%) in comparison with the cationic lipids Lipofectamine(TM)2000 and X-tremeGENE. In addition, the rate of cell toxicity in presence of FuGENE-HD was less than 5%. In summary, the cationic lipid FuGENE-HD indicates a suitable potential to transfer DNA into HeLa cells and it can be an efficient reagent for gene delivery for HeLa cells in vitro. Moreover, it is worth designing and optimizing gene transfer experiments for other cell lines with FuGENE-HD due to its low toxicity and high efficiency.

Genomic characterization of some Iranian children with idiopathic mental retardation using array comparative genomic hybridization

BACKGROUND

Mental retardation (MR) has a prevalence of 1-3% and genetic causes are present in more than 50% of patients. Chromosomal abnormalities are one of the most common genetic causes of MR and are responsible for 4-28% of mental retardation. However, the smallest loss or gain of material visible by standard cytogenetic is about 4 Mb and for smaller abnormalities, molecular cytogenetic techniques such as array comparative genomic hybridization (array CGH) should be used. It has been shown that 15-25% of idiopathic MR (IMR) has submicroscopic rearrangements detectable by array CGH. In this project, the genomic abnormalities were investigated in 32 MR patients using this technique.

MATERIALS AND METHODS

Patients with IMR with dysmorphism were investigated in this study. Karyotype analysis, fragile X and metabolic tests were first carried out on the patients. The copy number variation was then assessed in a total of 32 patients with normal results for the mentioned tests using whole genome oligo array CGH. Multiple ligation probe amplification was carried out as a confirmation test.

RESULTS

In total, 19% of the patients showed genomic abnormalities. This is reduced to 12.5% once the two patients with abnormal karyotypes (upon re-evaluation) are removed.

CONCLUSION

The array CGH technique increased the detection rate of genomic imbalances in our patients by 12.5%. It is an accurate and reliable method for the determination of genomic imbalances in patients with IMR and dysmorphism.

Investigation of the asporin gene polymorphism as a risk factor for knee osteoarthritis in Iran

Osteoarthritis (OA) is a degenerative disease of the joints characterized by degradation of the hyaline articular cartilage and remodeling of the subchondral bone with sclerosis. The asporin (ASPN) gene encodes a cartilage extracellular protein belonging to the small leucine-rich proteoglycan family. Polymorphisms in the aspartic acid (D) repeat region in the second exon of this gene, which consist of GAT repeats, are associated with OA susceptibility. The D14 allele, which contains 14 D-repeats, is associated with increased OA susceptibility in the Japanese and the Han Chinese but is not an important factor in OA etiology among Caucasians, though the D15 allele is a risk allele for the Greek population. To examine the possibility of this controversial association, we explored the effect of ASPN on Iranians with knee OA. The D-repeat polymorphism was genotyped in 100 knee OA patients and 100 controls, and the allelic association of the D-repeat was examined. Our data suggest that the D15 allele could be considered a risk allele significant only for women (P = .045, odds ratio = 1.73, 95% confidence interval [CI] = 1.01-2.94) in the Iranian population. This association is in part similar to that found for the Greek population.

Utility of the multivariate approach in predicting β-thalassemia intermedia or β-thalassemia major types In Iranian patients

Recently, five genetic modifiers [β-globin mutations, coinheritance of α-thalassemia (α-thal), XmnI polymorphism and single nucleotide polymorphisms (SNPs) in the BCL11A and HBS1L-MYB loci] were used to predict the β-thal major (β-TM) or β-thal intermedia (β-TI) types in 106 French patients with 83.2% accuracy. The dichotomous grouping was based on the age when the patient received his/her first transfusion (4 years). Here, a similar study was conducted in a cohort of 306 Iranian β-thal patients having distinct β-globin mutations and minor allele frequencies of key SNPs in these loci. Multivariate regression analyses and a simple scoring system were used to predict the β-TM/β-TI types using three scenarios: 1) when considering only the severe β-TM and the mild β-TI cases, 2) using clinical parameters for β-thal typing, and 3) using age at first transfusion as the basis for classification. Using these scenarios, the β-thal types could be correctly predicted in 77.6, 75.5 and 68.0% of cases, respectively.

Serotonin Transporter Polymorphism (5-HTTLPR) and Citalopram Effectiveness in Iranian Patients with Major Depressive Disorder

OBJECTIVE

Several studies have implicated the 5-HTTLPR polymorphism in treatment outcomes of selective serotonin re-uptake inhibitors in patients with major depression. The aim of this study was to examine the association between polymorphism in the serotonin transporter gene and citalopram effectiveness in Iranian patients suffering from major depressive disorder (MDD).

METHODS

The sample consisted of 104 patients, with Fars ethnic background, who were diagnosed according to DSM-IV-TR criteria. Beck Depression inventory was used to evaluate the severity of the symptoms during the follow-up, and to determine clinical response of the patients at 4th and 8th week, respectively.

RESULTS

Our results showed a correlation between the genotype and response to antidepressant drug citalopram, (odds ratios for L/S and L/L were 3.90 (95 percent CI: 1.29- 11.80) and 1.90 (95 percent CI: 0.72-5.08), respectively).

CONCLUSION

In conclusion, our results reveal that genetic variation of serotonin transporter is involved in clinical remission of major depressive episodes in Iranian patients after citalopram treatment.

cAMP response element-binding protein 1 is required for hydroxyurea-mediated induction of γ-globin expression in K562 cells

1. Hydroxyurea (HU) is a drug used for the treatment of haemoglobinopathies. Hydroxyurea functions by upregulating γ-globin transcription and fetal haemoglobin (HbF) production in erythroid cells. The K562 erythroleukaemia cell line is widely used as a model system in which to study the mechanism of γ-globin induction by HU. However, the transcription factors required for the upregulation of γ-globin expression by HU in K562 cells have not been identified. Similarities between the HU and sodium butyrate (SB) pathways suggest cAMP response element-binding protein (CREB) 1 as a potential candidate. Thus, the aim of the present study was to investigate the possible role of CREB1 in the HU pathway. 2. Experiments were performed using transient and stable RNA interference (RNAi) to show that CREB1 is necessary for HU-mediated induction of γ-globin expression and haemoglobin production in K562 cells. 3. Furthermore, western blot analyses demonstrated that CREB1 becomes phosphorylated in a dose-dependent manner after HU (100-400 µmol/L) treatment of K562 cells for 72 h. 4. We also investigated role of a Gγ promoter CREB1 response element (G-CRE) in this pathway. Quantitative amplification refractory mutation system-polymerase chain reaction experiments were performed to demonstrate that HU induces the expression of both Gγ and Aγ in this cell line. In addition, electrophoretic mobility shift assays were used to show that levels of CREB1 complexes binding to the G-CRE site are increased following HU treatment and are decreased in CREB1-knockdown cells. 5. The results suggest that CREB1 is necessary for γ-globin induction by HU in K562 cells, a role that may be mediated, in part, through the G-CRE element.

Iranian hereditary hemochromatosis patients: baseline characteristics, laboratory data and gene mutations

BACKGROUND

Hereditary hemochromatosis (HH) is the most common autosomal recessive disorder in white people, characterized by highly abnormal uptake of iron from the gastrointestinal tracts. Recently, mutation studies have focused to detect the genes responsible for HH.

MATERIAL/METHODS

In this cross-sectional study, 12 HH patients were recruited, who were referred to Firoozgar Hospital, Tehran, Iran. In addition to the clinical assessments, a complete laboratory evaluation, imaging modalities, histopathologic assessment, atomic absorption spectrophotometry and gene mutation study were performed. The genetic study for HFE gene mutation was examined for all of the patients since 2006, while non-HFE mutation was conducted since December 2010 (only for 1 of them).

RESULTS

Twelve patients were evaluated consisting of 11 men and 1 woman, with the mean age of 39.58±12.68 yr. The average of atomic iron loads was 13.25±4.83-fold higher than normal standards. Four patients had heterozygotic mutation of H63D (33.3%). There was no significant difference in either the iron load of liver (P=0.927) and heart (P=0.164) or serum concentration of ferritin (P=0.907) and TIBC (P=0.937) between the HFE-mutant and without HFE mutation HH cases.

CONCLUSIONS

In contrast to other studies, C282Y mutation was not detected in any of our Iranian HH patients. Heterozygotic mutations of H63D (HFE) and TFR2 (non-HFE) genes were found to be more common in these patients. Similar to previous reports, these mutations were not found to be significantly associated with severity of presentation in HH patients.

Novel mutations responsible for α-thalassemia in Iranian families

α-Thalassemia (α-thal) is usually caused by deletions on the α-globin gene cluster and the role of point mutations is less well investigated. In the present study, a total of 1048 individuals with hypochromic microcytic anemia, who did not present the most common α-thal deletions, were referred for α-globin gene DNA sequencing. The nucleotide changes were studied and a total of five new mutations was identified, of which three were located on the α2 gene [codon7 (Lys→Stop), codon 34 (Leu→Pro) and codon 83 (Leu→Arg)] and two on the α1 gene [IVS-I-116 (A>G) and codon 44 (+C)]. These novel mutations not only explain new findings by molecular analysis of the α-globin gene but also have clinical importance due to their changes in α-globin production in means of decreased hemoglobin (Hb) related values. Moreover, considerations of its role in combination with other mutations, and the possibility of causing Hb H (β4) are yet to be studied.

A mutation causes MuSK reduced sensitivity to agrin and congenital myasthenia

Congenital myasthenic syndromes (CMSs) are a heterogeneous group of genetic disorders affecting neuromuscular transmission. The agrin/muscle-specific kinase (MuSK) pathway is critical for proper development and maintenance of the neuromuscular junction (NMJ). We report here an Iranian patient in whom CMS was diagnosed since he presented with congenital and fluctuating bilateral symmetric ptosis, upward gaze palsy and slowly progressive muscle weakness leading to loss of ambulation. Genetic analysis of the patient revealed a homozygous missense mutation c.2503A>G in the coding sequence of MUSK leading to the p.Met835Val substitution. The mutation was inherited from the two parents who were heterozygous according to the notion of consanguinity. Immunocytochemical and electron microscopy studies of biopsied deltoid muscle showed dramatic changes in pre- and post-synaptic elements of the NMJs. These changes induced a process of denervation/reinnervation in native NMJs and the formation, by an adaptive mechanism, of newly formed and ectopic NMJs. Aberrant axonal outgrowth, decreased nerve terminal ramification and nodal axonal sprouting were also noted. In vivo electroporation of the mutated MuSK in a mouse model showed disorganized NMJs and aberrant axonal growth reproducing a phenotype similar to that observed in the patient's biopsy specimen. In vitro experiments showed that the mutation alters agrin-dependent acetylcholine receptor aggregation, causes a constitutive activation of MuSK and a decrease in its agrin- and Dok-7-dependent phosphorylation.

Detection of HER2 status in breast cancer: comparison of current methods with MLPA and real-time RT-PCR

Human epidermal growth factor receptor (HER) status is an important prognostic factor in breast cancer. There is no globally accepted method for determining its status, and which method is most precise is still a matter of debate. We here analyzed HER2 mRNA expression by quantitative reverse transcription-PCR (qRT-PCR) and HER2 DNA amplification using multiplex ligation-dependent probe amplification (MLPA). In parallel, we performed a routine evaluation of HER2 protein by immunohistochemistry (IHC). To assess the accuracy of the RT-PCR and MLPA techniques, a combination of IHC and fluorescence in situ hybridization (FISH) was used, substituting FISH when the results of IHC were ambiguous (2+) and for those IHC results that disagreed with MLPA and qRT-PCR, this approach being termed IHC-FISH. The IHC results for four samples were not compatible with the MLPA and qRT-PCR results; the MLPA and qRT-PCR results for these samples were confirmed by FISH. The correlations between IHC-FISH and qRT-PCR or MLPA were 0.945 and 0.973, respectively. The ASCO/CAP guideline IHC/FISH correlation with MLPA was (0.827) and with RT-PCR was (0.854). The correlations between the IHC results (0, 1+ as negative, and 3+ as positive) and qRT-PCR and MLPA techniques were 0.743 and 0.831, respectively. Given the shortcomings of IHC analysis and greater correlations between MLPA, qRT-PCR, and FISH methods than IHC analysis alone with each of these three methods, we propose that MLPA and real-time PCR are good alternatives to IHC. However a suitable cut-off point for qRT- PCR is a prerequisite for determining the exact status of HER2.

The spectrum of α-thalassemia mutations in the Kurdish population of Northeastern Iraq

In an attempt to determine the spectrum of α-thalassemia (α-thal) mutations in the Kurdish population of Northeastern (NE) Iraq, a total of 101 unrelated adults with unexplained hypochromia and/or microcytosis were enrolled. α-Thalasssemia mutations were characterized by gap polymerase chain reaction (gap-PCR), multiplex PCR (m-PCR) and reverse hybridization and sequencing for both α genes. A total of nine α-thal mutations were characterized including four deletional ones: -α(3.7) (rightward), - -(MED-I), -(α)(20.5), -α(4.2) (leftward) and five nondeletional ones: α(polyA1)α, αα(Adana), α(-5 nt)α, α(CS)α and α(polyA2)α. These determinants were arranged in 12 different genotypes, the most frequent of which were: -α(3.7)/αα, - -(MED-I)/αα, -α(3.7)/-α(3.7), α(polyA1)α/αα, αα(Adana)/αα and -(α)(20.5)/αα. This pattern is similar to that reported in Turkey, western (W) Iran, Cyprus and Greece, and to some extent, different from the pattern observed in the Arabian Peninsula.

Mutational screening of ARX gene in Iranian families with X-linked intellectual disability

BACKGROUND

Mutations in the human aristaless-related homeobox (ARX) gene are amongst the major causes of developmental and neurological disorders. They are responsible for a wide spectrum of phenotypes, including nonsyndromic X-linked intellectual disability (NS-XLID), and syndromic (XLIDS) forms such as X-linked lissencephaly with abnormal genitalia (XLAG), Partington syndrome (PRTS), and X-linked infantile spasm syndrome (ISSX). The recurrent 24 bp duplication mutation, c.428_451dup(24 bp), is the most frequent ARX mutation, which accounts for ~40% of all cases reported to date.

METHODS

We have screened the entire coding sequences of the ARX gene in 65 Iranian families with intellectual disabilities in order to obtain the relative prevalence of ARX mutations. At first these families were screened for the most recurrent mutation, the c.428_451dup(24 bp). For samples with negative results, single strand conformation polymorphism (SSCP) analysis was performed.

RESULTS

We identified one family with the c.428_451dup(24 bp) duplication. Three shifts (one shift in exon 5 and two shifts in exon 4) were also identified among the total families. According to the results of the sequencing analysis, two shifts were not associated with any mutation and the other one was a c.1347C>T (p.G449G) substitution in exon 4.

CONCLUSION

Hence, we suggest that molecular analysis of ARX mutations as a second cause of XLID should be considered as routine diagnostic procedure in any male who presents with either NS-XLID or XLIDS.

A novel mutation in MCPH1 gene in an Iranian family with primary microcephaly

Primary microcephaly (MCPH) is a genetic disorder in which affected individuals present with a head circumference 3 standard deviations (SDs) below the age- and sex-related mean and is accompanied by mental retardation without further associated malformations. Here we report a patient with sporadic MCPH from Northwest of Iran who was investigated for MCPH1 locus. Clinical examination and karyotype analyses were performed and microsatellite based mapping was done by using flanking and intragenic short tandem repeat (STR) markers for MCPH1 locus. For these markers the affected individual was homozygote and the parents were heterozygote. According to this pattern of allele sharing and also the cytogenetic findings, mutation screening of Microcephalin gene was performed and subsequent sequencing revealed a novel mutation in Microcephalin gene.

Hydroxyurea responsiveness in β-thalassemic patients is determined by the stress response adaptation of erythroid progenitors and their differentiation propensity

β-thalassemia is caused by mutations in the β-globin locus resulting in loss of, or reduced, hemoglobin A (adult hemoglobin, HbA, α2β2) production. Hydroxyurea treatment increases fetal γ-globin (fetal hemoglobin, HbF, α2γ2) expression in postnatal life substituting for the missing adult β-globin and is, therefore, an attractive therapeutic approach. Patients treated with hydroxyurea fall into three categories: i) 'responders' who increase hemoglobin to therapeutic levels; (ii) 'moderate-responders' who increase hemoglobin levels but still need transfusions at longer intervals; and (iii) 'non-responders' who do not reach adequate hemoglobin levels and remain transfusion-dependent. The mechanisms underlying these differential responses remain largely unclear. We generated RNA expression profiles from erythroblast progenitors of 8 responder and 8 non-responder β-thalassemia patients. These profiles revealed that hydroxyurea treatment induced differential expression of many genes in cells from non-responders while it had little impact on cells from responders. Part of the gene program up-regulated by hydroxyurea in non-responders was already highly expressed in responders before hydroxyurea treatment. Baseline HbF expression was low in non-responders, and hydroxyurea treatment induced significant cell death. We conclude that cells from responders have adapted well to constitutive stress conditions and display a propensity to proceed to the erythroid differentiation program.

Prevalence of ACTN3 (the athlete gene) R577X polymorphism in Iranian population

BACKGROUND

Ability of athletes in speed or endurance contests somehow is determined by inherited muscle fiber types. One of the important genes involved in sport genetics is ACTN3 that is located on chromosome 11q13-q14 and encodes α-actinin-3, which belongs to highly conserved family of α-actinin proteins. Genetic analysis of α-actinin-3 gene has showed a polymorphism R577X (rs1815739), which results in premature stop codon and leads to non functional α-actnin-3 protein. ACTN3 genotype can contribute to the performance in elite and endurance activities. R577X polymorphism replaces arginine by stop codon. Individuals homozygous for R577 have full copy of α-actinin-3 and elite and power sprint athletes show significantly higher frequency of 577R allele. In the other hand, some studies represented that X allele have high level of frequency in endurance athletes. However, this data remains controversial Since there is no information about the frequency of ACTN3 genotype in our population therefore as the first step it is essential to determine the genetic background of Iranian population. The objective of this study was to genotype normal Iranian individuals to determine the prevalence of each allele in our population.

METHODS

We used PCR-RFLP method for genotyping 210 normal individuals.

RESULTS

Total of 210 Iranian normal individuals for distribution of R577X and R alleles were genotyped. The different genotypes were as follow; 24% RR (50/210), 65%RX (136/210) and 11%XX (24/210), with allelic distribution of 0.56 and 0.44 for 577R and 577X alleles of ACTN3.

CONCLUSION

This allelic distribution for Iranian's is more close to Caucasian population, which is concurrent with the route of ancient human's migration from Iran Plateau toward Europe. Our results showed no different patterns of allelic distribution among female and males, which was the same in other studies too, although some differences has been reported in the studies on athletes population.

A comprehensive study to determine heterogeneity of autosomal recessive nonsyndromic hearing loss in Iran

Hearing loss is the most common sensory disorder worldwide and affects 1 of every 500 newborns. In developed countries, at least 50% of cases are genetic, most often resulting in nonsyndromic deafness (70%), which is usually autosomal recessive (∼80%). Although the cause of hearing loss is heterogeneous, mutations in GJB2 gene at DFNB1 locus are the major cause of autosomal recessive nonsyndromic hearing loss (ARNSHL) in many populations. Our previous study showed that mutations of GJB2 gene do not contribute to the major genetic load of deafness in the Iranian population (∼16%). Therefore, to define the importance of other genes in contributing to an ARNSHL phenotype in the Iranian population, we used homozygosity mapping to identify regions of autozygosity-by-descent in 144 families which two or more progeny had ARNSHL but were negative for GJB2 gene mutations. Using flanking or intragenic short-tandem repeat markers for 33 loci we identified 33 different homozygous variations in 10 genes, of which 9 are novel. In aggregate, these data explain ∼40% of genetic background of ARNHSL in the Iranian population.

The spectrum of GJB2 mutations in the Iranian population with non-syndromic hearing loss--a twelve year study

OBJECTIVE

Mutations in GJB2, encoding connexin 26 (CX26), are causally related to autosomal recessive form of non-syndromic hearing loss (NSHL) at the DFNB1 locus and autosomal dominant NSHL at the DFNA3 locus. In this study, we investigated the prevalence of GJB2 mutations in the Iranian deaf population.

METHODS

A total of 2322 deaf probands presenting the ethnically diverse Iranian population were screened for variants in GJB2. All persons were first screened for the c.35delG mutation, as this variant is the most prevalent GJB2-deafness causing mutation in the Iranian population. In all persons carrying zero or one c.35delG allele, exons 1 and 2 were then sequenced.

RESULTS

In total, 374 (~16%) families segregated GJB2-related deafness caused by 45 different mutations and 5 novel variants. The c.35delG mutation was most commonly identified and accounts for ~65% of the GJB2 mutations found in population studied.

CONCLUSION

Our data also show that there is a gradual decrease in the frequency of the c.35delG mutation and of GJB2-related deafness in general in a cline across Iran extending from the northwest to southeast.

Screening for MYO15A gene mutations in autosomal recessive nonsyndromic, GJB2 negative Iranian deaf population

MYO15A is located at the DFNB3 locus on chromosome 17p11.2, and encodes myosin-XV, an unconventional myosin critical for the formation of stereocilia in hair cells of cochlea. Recessive mutations in this gene lead to profound autosomal recessive nonsyndromic hearing loss (ARNSHL) in humans and the shaker2 (sh2) phenotype in mice. Here, we performed a study on 140 Iranian families in order to determine mutations causing ARNSHL. The families, who were negative for mutations in GJB2, were subjected to linkage analysis. Eight of these families showed linkage to the DFNB3 locus, suggesting a MYO15A mutation frequency of 5.71% in our cohort of Iranian population. Subsequent sequencing of the MYO15A gene led to identification of 7 previously unreported mutations, including 4 missense mutations, 1 nonsense mutation, and 2 deletions in different regions of the myosin-XV protein.

The XmnI and BCL11A single nucleotide polymorphisms may help predict hydroxyurea response in Iranian β-thalassemia patients

Hydroxyurea (HU), a drug which can reactivate fetal hemoglobin (Hb F) production, is frequently prescribed to β-thalassemia (β-thal) patients. However, transfusion requirements of only a subset of patients are reduced upon HU treatment. Because of its potential side-effects, targeted prescription of HU is imperative. To identify genetic markers that correlate with drug response, we have carried out a retrospective association study of single nucleotide polymorphisms (SNPs) in three Hb F quantitative trait loci (QTLs): the XmnI polymorphism, BCL11A, and the HBS1L-MYB intergenic region, with the response to HU in a cohort of 81 transfusion-dependent Iranian β-thal patients. An increase in blood transfusion intervals post-therapy was used to measure drug response. Our results suggest that presence of the XmnI T/T genotype or the BCL11A rs766432 C allele correlates strongly with response to HU (p <0.001). Accordingly, these markers may be used to accurately predict the HU response of Iranian β-thal patients.

Two novel SLC26A4 mutations in Iranian families with autosomal recessive hearing loss

OBJECTIVE

Due to the fact that SLC26A4 has been suggested as the second cause of hearing loss (HL) in Iran as well as many other countries, obtaining more comprehensive information about SLC26A4 mutations can facilitate more efficient genetic services to the patients with hereditary hearing loss. This investigation aims to detect genetic cause of two Iranian families with hearing loss.

METHODS

In the present study, genetic linkage analysis via 4 short tandem repeat markers linked to SLC26A4 was performed for two consanguineous families originating from Hormozgan and Chaharmahal va Bakhtiari provinces of Iran, co-segregating autosomal recessive hearing loss and showed no GJB2 mutations in our preliminary investigation. For identification of mutations, DNA sequencing of SLC26A4 including all the 21 exons, exon-intron boundaries and the promoter was carried out.

RESULTS

The results showed linkage to this gene in both families. After sequencing, two novel SLC26A4 mutations (c.65-66insT in exon 2 and c.2106delG in exon 19) were revealed in the two studied families.

CONCLUSION

Results of this study stress the necessity of considering the analysis of SLC26A4 in molecular diagnosis of deafness especially when phenotypes such as goiter or enlarged vestibular aqueduct are present.