Mutational and phenotypic spectra of KCNE1 deficiency in Jervell and Lange‐Nielsen Syndrome and Romano‐Ward Syndrome

KCNE1 encodes a regulatory subunit of the KCNQ1 potassium channel‐complex. Both KCNE1 and KCNQ1 are necessary for normal hearing and cardiac ventricular repolarization. Recessive variants in these genes are associated with Jervell and Lange‐Nielson syndrome (JLNS1 and JLNS2), a cardio‐auditory syndrome characterized by congenital profound sensorineural deafness and a prolonged QT interval that can cause ventricular arrhythmias and sudden cardiac death. Some normal‐hearing carriers of heterozygous missense variants of KCNE1 and KCNQ1 have prolonged QT intervals, a dominantly inherited phenotype designated Romano‐Ward syndrome (RWS), which is also associated with arrhythmias and elevated risk of sudden death. Coassembly of certain mutant KCNE1 monomers with wild‐type KCNQ1 subunits results in RWS by a dominant negative mechanism. This paper reviews variants of KCNE1 and their associated phenotypes, including biallelic truncating null variants of KCNE1 that have not been previously reported. We describe three homozygous nonsense mutations of KCNE1 segregating in families ascertained ostensibly for nonsyndromic deafness: c.50G>A (p.Trp17*), c.51G>A (p.Trp17*), and c.138C>A (p.Tyr46*). Some individuals carrying missense variants of KCNE1 have RWS. However, heterozygotes for loss‐of‐function variants of KCNE1 may have normal QT intervals while biallelic null alleles are associated with JLNS2, indicating a complex genotype‐phenotype spectrum for KCNE1 variants.     

Molecular characterization of alpha-thalassemia in Pakistan

Common alpha-thalassemia (thal) rearrangements were studied in a normal random population and in six ethnic groups of Pakistan. Analyses of 204 individuals from the normal population revealed the presence of only the -alpha(3.7) allele with an overall frequency of 8.3%. Ethnic differences were statistically significant for Pashtoon vs. Balochi (p < 0.0005) and Pashtoon vs. Sindhi (p < 0.002). Two hundred and eighty-five thalassemia patients were also studied to identify rare alpha-thal alleles. In this group, 24.6% of the patients had one or two alpha genes deleted. Two rare alleles in the Pakistani population, -alpha(4.2) (0.2%) and alphaalphaalpha(anti3.7) (0.9%), were identified in these patients. The -alpha(4.2) allele was found only in Sindhis, while alphaalphaalpha(anti3.7) was present in Punjabis, Sindhis and Balochis. Five patients with triplicated alpha genes were homozygous for either the beta+ or the beta(0) genotype.     

Determination of Multi-residue Insecticides of Organochlorine,Organophosphorus, and Pyrethroids in Wheat

The undesirable effects of green revolution include residues of extensively used pesticides in various food commodities. Several studies showed that pesticides could cause health problems. Keeping in view the problem of pesticide residues in various food commodities, the present study was conducted on domestic stored wheat as well as on imported wheat for the qualitative and quantitative analysis of organochlorine, organophosphorus and pyrethroids. Among the imported wheat, 22.5% samples were found contaminated by organophosphorus (chlorpyrifos 0.073–0.230 μg/g, malathion 0.0419–0.1003 μg/g) and pyrethroids (cypermethrin 0.1404–0.2005 μg/g, permethrin 0.0140–0.0480 μg/g) while in domestic wheat 6.7% samples were found contaminated by pyrethroids (deltamethrin 0.0650–1.2903 μg/g) only. Method used for extraction and analysis of insecticides was validated both by recovery studies and inter laboratory comparison proficiency test. The method recovery results show that the average recovery of the fortified wheat samples was in the range of 73.77%–100.17% with the RSD in the range of 2.21–9.27 whereas, the Z-scores of the inter laboratory comparison proficiency test’s result was less than 2.     

Origins and frequencies of SLC26A4 (PDS) mutations in east and south Asians: global implications for the epidemiology of deafness

Recessive mutations of SLC26A4 (PDS) are a common cause of Pendred syndrome and non-syndromic deafness in western populations. Although south and east Asia contain nearly one half of the global population, the origins and frequencies of SLC26A4 mutations in these regions are unknown. We PCR amplified and sequenced seven exons of SLC26A4 to detect selected mutations in 274 deaf probands from Korea, China, and Mongolia. A total of nine different mutations of SLC26A4 were detected among 15 (5.5%) of the 274 probands. Five mutations were novel and the other four had seldom, if ever, been identified outside east Asia. To identify mutations in south Asians, 212 Pakistani and 106 Indian families with three or more affected offspring of consanguineous matings were analysed for cosegregation of recessive deafness with short tandem repeat markers linked to SLC26A4. All 21 SLC26A4 exons were PCR amplified and sequenced in families segregating SLC26A4 linked deafness. Eleven mutant alleles of SLC26A4 were identified among 17 (5.4%) of the 318 families, and all 11 alleles were novel. SLC26A4 linked haplotypes on chromosomes with recurrent mutations were consistent with founder effects. Our observation of a diverse allelic series unique to each ethnic group indicates that mutational events at SLC26A4 are common and account for approximately 5% of recessive deafness in south Asians and other populations.     

Preconditioning enhances cell survival and differentiation of stem cells during transplantation in infarcted myocardium

AIMS: We hypothesized that preconditioning (PC) with stromal-derived factor 1 alpha (SDF-1) significantly enhances cell survival, proliferation, and engraftment of bone marrow-derived mesenchymal stem cells (MSCs) via SDF-1/CXCR4 signaling. METHODS AND RESULTS: MSCs were cultured and then incubated in medium for 60 min without SDF-1 (control group) or with SDF-1 0.05 microg/mL (SDF-1 group) or CXCR4-selective antagonist, AMD 3100 (AMD) (5 microg/mL, AMD group) or SDF-1 and AMD (0.05 microg/mL, 5 microg/mL, respectively, SDF-1+AMD group). MSCs were treated for 60 min, washed in normal medium, and then exposed to H2O2 (100 micromol/L) for 60 min to determine the effects of various treatments on cell injury, viability, and proliferation. For in vivo studies, rats were grouped (n = 6) after left anterior descending coronary artery ligation to receive 20 microL Dulbecco's modified Eagle's medium without cells or with 5 x 10(5) non-preconditioned MSCs (control group), SDF-1 preconditioned MSCs (SDF-1 group), AMD (AMD group), or MSCs treated with SDF-1 plus AMD (SDF-1+AMD group). Heart function, infarct size, fibrosis, and MSC proliferation and differentiation in infarcted myocardium were determined after 4 weeks. In vitro data showed a marked increase in cell viability and proliferation following SDF-1 PC. In vivo data in preconditioned group showed a robust cell proliferation, reduction in infarct size and fibrosis, and significant improvement in cardiac function. Effects of SDF-1 PC were abrogated by CXCR4 antagonist. CONCLUSION: We conclude that PC with the chemokine SDF-1 suppresses MSCs apoptosis, enhances their survival, engraftment, and vascular density, and improves myocardial function via SDF/CXCR4 signaling. Chemokine PC is a novel approach for enhancing stem cell survival and regeneration of infarcted myocardium.     

Mutation spectrum of MYO7A and evaluation of a novel nonsyndromic deafness DFNB2 allele with residual function

Recessive mutations of MYO7A, encoding unconventional myosin VIIA, can cause either a deaf-blindness syndrome (type 1 Usher syndrome; USH1B) or nonsyndromic deafness (DFNB2). In our study, deafness segregating as a recessive trait in 24 consanguineous families showed linkage to markers for the DFNB2/USH1B locus on chromosome 11q13.5. A total of 23 of these families segregate USH1 due to 17 homozygous mutant MYO7A alleles, of which 14 are novel. One family segregated nonsyndromic hearing loss DFNB2 due to a novel three-nucleotide deletion in an exon of MYO7A (p.E1716del) encoding a region of the tail domain. We hypothesized that DFNB2 alleles of MYO7A have residual myosin VIIA. To address this question we investigated the effects of several mutant alleles by making green fluorescent protein (GFP) tagged cDNA expression constructs containing engineered mutations of mouse Myo7a at codons equivalent to pathogenic USH1B and DFNB2 alleles of human MYO7A. We show that in transfected mouse hair cells an USH1B mutant GFP-myosin VIIa does not localize properly to inner ear hair cell stereocilia. However, a GFP-myosin VIIa protein engineered to have an equivalent DFNB2 mutation to p.E1716del localizes correctly in transfected mouse hair cells. This finding is consistent with the hypothesis that p.E1716del causes a less severe phenotype (DFNB2) than the USH1B-associated alleles because the resulting protein retains some degree of normal function.