Genetic analysis for 2 females carrying idic(Y)(p) and with sex development disorders / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To investigate the phenotype-genotype association of isodicentromere Y chromosome by analysis of two female patients carrying the chromosome with sexual development disorders.</p><p><b>METHODS</b>The karyotypes of the two patients were determined by application of conventional G banding of peripheral blood samples and fluorescence in situ hybridization (FISH). PCR was applied to detect the presence of SRY gene.</p><p><b>RESULTS</b>Conventional karyotype analysis showed case 1 to be a mosaic: mos.45,X[38]/46,X,+mar[151]/47,XY,+mar[5]/47,X,+mar × 2[2]/46,XY[4], FISH showed that 12 different cell lines were presented in the karyotype of case 1 and partial cell lines with SRY gene, the marker is an isodicentromere Y chromosome [idic(Y)(p)]. No mutation was found in the SRY gene. The karyotype of case 2 was mos.45,X[25]/46,X,+mar[35]. FISH showed the marker to be an idic(Y)(p) without the SRY gene.</p><p><b>CONCLUSION</b>The karyotype of patients carrying idic(Y)(p) seems unstable, and female patients have the characteristics of short stature and secondary sexual hypoplasia. Karyotype analysis combined with FISH analysis can accurately determine the breakpoint of idic(Y) and identify the types of complex mosaic, which may facilitate genetic counseling and prognosis.</p>

Study of a Bethlem myopathy pedigree resulted from a novel mutation of COL6A3 gene / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To determine the molecular etiology for a muscular dystrophy pedigree with target region sequencing platform using hereditary myopathy capture array.</p><p><b>METHODS</b>Specific gene testing was performed based on the clinical diagnosis. Since no pathogenic mutation was found, target region sequencing with hereditary myopathy capture array combined with Sanger sequencing and bioinformatics analysis were employed in turn. PolyPhen and NCBI were used to evaluate the pathogenicity of identified mutation and conservation of the gene.</p><p><b>RESULTS</b>Target region sequencing indicated the proband has carried a heterozygous c.3353 A>C mutation of COL6A3 gene, which was confirmed by Sanger-sequencing in 4 affected individuals from the family. The same mutation was not detected in healthy members of the pedigree. Bioinformatics analysis suggested that the mutation has caused a highly pathogenic amino acid substitution from Histidine to Proline. The affected patients featured normal intelligence with mild myogenic damage by muscle biopsy, slightly increased serum creatine kinase and slow disease progression, which was consistent with Bethlem myopathy.</p><p><b>CONCLUSION</b>Target region sequencing is an effective and efficient method for genetic testing. The heterozygous c.3353A>C mutation in exon 8 of the COL6A3 gene probably underlies the Bethlem myopathy with autosomal dominant inheritance.</p>

Analysis of a novel mutation of AR gene in a patient featuring mild androgen insensitivity syndrome / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To investigate the clinical and molecular genetics characteristics of a patient with mild androgen insensitivity syndrome (MAIS).</p><p><b>METHODS</b>Clinical data of the patient was collected, and DNA was isolated from peripheral blood sample. Eight exons of AR gene were amplified by PCR with specific primers and directly sequenced by Sanger method. The results were compared with standard sequences from GenBank. Online Polyphen-2 software was applied to predict the effect of mutation on the protein function and compare the conservation of the sequence at the mutation site in various species. The exon of the AR gene containing the mutated site was analyzed in 90 unrelated normal males using PCR and restrictive digestion with Sfa NI.</p><p><b>RESULTS</b>Sequence analysis has detected a novel missense mutation in codon 176 of exon 1 (Ser176Arg) of the AR gene. Analysis with polyphen-2 software has indicated the codon to be highly conserved across various species, and that the S176A mutation has caused damage to the protein structure and function (prediction score=0.999). The same mutation was not detected in 90 healthy males.</p><p><b>CONCLUSION</b>The S176A mutation of the AR gene may contribute to the mild androgen insensitivity syndrome.</p>