Analysis on genetic polymorphism of 5 STR loci selected from X chromosome / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To select short tandem repeats(STR) from X chromosome.</p><p><b>METHODS</b>STR is a universal genetic marker that has changeable polymorphism and stable heredity in human genome. It is a specific DNA segment composed of 2-6 base pairs as its core sequence. It is an ideal DNA marker used in linkage analysis and gene mapping. In this study, 8 short tandem repeats were selected from two genomic clones on X chromosome by using BCM Search Launcher. Primers amplifying the STR loci were designed by using Primer 3.0 according to the unique sequence flanking the STRs. Polymorphisms of the short tandem repeats in Chinese population were evaluated by PCR amplification and PAGE.</p><p><b>RESULTS</b>Five of these STRs were polymorphic. Chi-square test indicated that the distribution of genotypes agreed with Hardy-Weinberg equilibrium (P>0.05).</p><p><b>CONCLUSION</b>Five polymorphic short tandem repeats have been identified on chromosome X and will be useful for linkage analysis and gene mapping.</p>

Fine mapping of Smith-Fineman-Myers syndrome and exclusion of GPC3, GPCR2 MST4 and GLUD2 as candidate genes / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>Smith-Fineman-Myers syndrome (SFMS) is an X-linked mental retardation syndrome. The authors had ascertained a large Chinese family with SFMS from Shandong and had mapped the disease locus to an interval of 19.8 Mb on Xq25 flanked by markers DXS8064 and DXS8050. Further investigation suggested that SFMS exhibited locus heterogeneity. In this study for facilitating the identification of the gene responsible for SFMS, the additional markers were analyzed to narrow down the candidate region, and four candidate genes (GPC3, MST4,GPCR2 and GLUD2) were chosen and screened for disease-causing mutation.</p><p><b>METHODS</b>PCR and denaturing polyacrylamide gel electrophoresis were used to genotype 13 new polymorphic markers distributed within the candidate region. Mutation detection was accomplished by sequencing the exons and intron-exon junctions of the candidate genes.</p><p><b>RESULTS</b>By analyzing 13 additional polymorphic markers, SFMS candidate region can be reduced to an interval of 10.18 Mb bounded by XSTR3 and XSTR4, and no disease-causing mutation was identified in the coding regions of four candidate genes.</p><p><b>CONCLUSION</b>GPCR2 GPC3, MST4 and GLUD2 were excluded as pathogenic genes for SFMS. The refined SFMS locus will assist in the identification and characterization of other candidate genes for SFMS.</p>