Gene mapping of a nonsyndromic hearing impairmint family / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To map the gene responsible for nonsyndromic hearing impairment in a consanguineous family.</p><p><b>METHODS</b>Firstly, X chromosome scanning was used to exclude X chromosome. Secondly, candidate gene analyzing and genome scanning were performed by homozygosity mapping. Then, additional markers flanking the tightly linked marker were tested to confirm linkage and decide the candidate region.</p><p><b>RESULTS</b>The nonsyndromic hearing impairment of this family was autosomal recessive. Twenty-five known genes were excluded. Autosomal genome scanning indicated that D17S1293 was tightly linked with disease gene. And further study mapped the disease gene to a 5.07 cM interval bounded by D17S1850 and D17S1818.</p><p><b>CONCLUSION</b>The disease gene of the family is mapped to a 5.07 cM interval between D17S1850 and D17S1818, which is a new locus of autosomal recessive nonsyndromic hearing impairment.</p>

Genomic structure of low density lipoprotein receptor related protein 5 gene / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To determine the genomic structure of low density lipoprotein receptor related protein 5 (LRP5) gene.</p><p><b>METHODS</b>cDNA sequence encoding LRP5 was used to screen genomic clones containing LRP5 gene by computer hybridization approach. By comparing the cDNA sequence of LRP5 with the genomic sequences, the genomic structure of LRP5 was determined, and then it was conformed by amplifying and sequencing the sequences of exons and splicing junction.</p><p><b>RESULTS</b>The genomic sequence of LRP5 gene was 131.6 kb in length, containing 23 exons and 22 introns. Three single nucleotide polymorphisms were detected within the coding sequences of LRP5 gene, namely A459G in exon 2, C2220T in exon 10 and G4416C in exon 21. Four polymorphic markers, D11S1917, D11S4087, D11S1337 and D11S4178, located in the 5' flank sequence, introns 1, 4, and 13 of the LRP5 gene, respectively.</p><p><b>CONCLUSION</b>The characterization of genomic structure of LRP5 gene allows the investigators to detect disease-causing mutation within the gene and further study the function of LRP5 gene.</p>

The C677T mutation in the methylenetetrahydrofolate reductase gene and its association with deep vein thrombophilia in Shandong Hans / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To study the prevalence of methylenetetrahydrofolate reductase (MTHFR) C677T genotype and its association with deep vei n thrombophilia in Chinese.</p><p><b>METHODS</b>Polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) analysis was conducted to examine mutation with 63 deep vein thrombophilic patients and 80 health controls in Shandong Hans. The genotype frequencies were calculated by gene counting in patients and controls, and an analysis was made on the association of MTHFR C677T mutation with deep venous thrombosis in Shandong Hans.</p><p><b>RESULTS</b>In case- controls, the frequencies of C/T heterozygote were 41.27% and 43.75%; whereas those of T/T homozygote were 52.38% and 36.25%. Significantly elevated mutation was observed in patients(Chi-square=6.372, P 0.01 OR(T/T)=4.552 95% confidence interval:1.440-14.390, Chi-square =6.742 P=0.009).</p><p><b>CONCLUSION</b>The C677T mutation of methylenetetrahydrofolate reductase gene is a risk factor associated with deep vein thrombophilia in Shandong Hans.</p>

Linkage analysis of X-linked nuclear protein gene in Smith-Fineman-Myers syndrome / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To determine the linkage between Smith-Fineman-Myers syndrome (SFMS) and X-linked nuclear protein(XNP) locus.</p><p><b>METHODS</b>Polymerase chain reaction and denaturing polyacrylamide gel electrophoresis were used to genotype two polymorphic short tandem repeats within XNP gene.</p><p><b>RESULTS</b>One of the two short tandem repeats was informative in SFMS family from Shandong, China. Recombination between SFMS locus and XNP gene was observed in the SFMS family.</p><p><b>CONCLUSION</b>XNP gene is not associated with the disease in the SFMS family from Shandong, China. SFMS exhibits locus heterogeneity at molecular level.</p>

Relationship between polymorphism of N-acetyltransferase 2 and genetic susceptibility to laryngeal carcinoma / 中华肿瘤杂志

<p><b>OBJECTIVE</b>To investigate the relationship between polymorphism of N-acetyltransferase (NAT2) gene and genetic susceptibility to laryngeal carcinoma.</p><p><b>METHODS</b>A case-control study on 62 laryngeal carcinoma patients and 56 controls was conducted. NAT2 alleles were differentiated by polymerase chain reaction-based restriction fragment length polymorphism (PCR-RFLP) methods using originally created PCR primers and genomic DNA extracted from peripheral white blood cells. Genetic risk for NAT2 genotype was analyzed by smoking index (SI, cigarettes smoked per day x years of smoking).</p><p><b>RESULTS</b>The frequency of NAT2 slow genotype was 80.6% in patients with laryngeal carcinoma and 60.7% in the controls, the difference of which was statistically significant (chi(2) = 5.70, P = 0.017). The odds ratios were 2.70 (95% CI 1.19 approximately 6.11). Among the individuals with NAT2 slow genotype at high level of cigarette smoking, there was a significantly higher risk of 5.64 (95% CI 1.77 approximately 17.92), while those at low level were considered the reference group (OR 1.38, 95% CI 0.42 approximately 4.52).</p><p><b>CONCLUSION</b>NAT2 slow genotype increases the risk of susceptibility to laryngeal carcinoma. The combined effect of NAT2 slow genotype and exposure to smoking is observed during the development of laryngeal cancer.</p>