Efficiency of multiplex ligation-dependent probe amplification combined with short tandem repeat linkage analysis for the prenatal diagnosis for Duchenne muscular dystrophy / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To investigate the efficiency of multiplex ligation-dependent probe amplification (MLPA) combined with short tandem repeat (STR) linkage analysis for the prenatal diagnosis for Duchenne muscular dystrophy (DMD).</p><p><b>METHODS</b>Gender of the fetus was first determined by the presence of Y chromosome sex-determining gene (SRY). Subsequently, combined MLPA and STR linkage analysis were applied for the probands, pregnant women and fetuses in 45 affected families.</p><p><b>RESULTS</b>Among the 45 families, 31 SRY-positive fetuses were identified, among whom six were diagnosed with DMD. For 14 SRY-negative fetuses, four were diagnosed as carriers. The remainders were normal.</p><p><b>CONCLUSION</b>MLPA can detect mutations in the exons of dystrophin gene, whilst STR linkage analysis can determine whether the fetus has inherited the maternal X chromosome bearing the mutant gene. As the result, the method can detect affected fetuses in which no exonic mutations are detected with MLPA. By combining the two methods, the diagnostic rate for DMD can be greatly improved.</p>

Detection and prenatal diagnosis for RS1 gene mutations in two Chinese families with X-linked juvenile retinoschisis / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To identify potential mutations of retinoschisis 1 (RS1) gene responsible for X-linked retinoschisis (XLRS) in two Chinese families.</p><p><b>METHODS</b>The 6 exons and flanking intronic regions were analyzed with PCR and direct sequencing.</p><p><b>RESULTS</b>Two RS1 mutations were identified in the two families, which included 1 frameshift mutation (c.573delG, p.Pro192fs) and 1 missense mutation (c.626G>A, p.Arg209His).</p><p><b>CONCLUSION</b>Two RS1 mutations have been identified, among which Pro192fs mutation is discovered for the first time in Chinese population. Above results may enrich our understanding of the clinical manifestations of XLRS and facilitated early diagnosis and genetic counseling for the disease.</p>

Analysis of CYP17A1 gene mutation in a child patient with 17 alpha-hydroxylase/17, 20-lyase deficiency / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To analyze CYP17A1 gene mutations in a child patient with 17 alpha-hydroxylase/17, 20-lyase deficiency (17OHD), and to review characteristics of CYP17A1 gene mutations in Chinese patients with 17OHD.</p><p><b>METHODS</b>Clinical data were collected. PCR and DNA sequencing were performed to detect mutations in the patient.</p><p><b>RESULTS</b>The patient has presented classical features of 17OHD including hypertension, hypokalemia, decreased sex hormones and plasma cortisol, and elevated blood adrenocorticotrophic hormone. A compound heterozygous mutation c.987C>A and c.985del was detected in the CYP17A1 gene, which resulted in two premature stop codons at positions 328 and 417.</p><p><b>CONCLUSION</b>A compound mutation, c.987C>A and c.985del, has been identified in a patient with 17OHD. Among CYP17A1 gene mutations identified in Chinese patients, missence mutations have been most common, and exons 5 and 8 have been the mutation hotspots.</p>

Significance of detecting free DNA from maternal plasma for the diagnosis of fetal chromosomal aneuploidies / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To determine the feasibility and accuracy of detecting numerical chromosomal abnormalities by high-flux sequencing analysis of free fetal DNA from maternal plasma.</p><p><b>METHODS</b>High-flux sequencing was applied to analyze fetal chromosome sequence copy numbers in 153 pregnant women. Fetal karyotyping was also carried out on amniocentesis samples.</p><p><b>RESULTS</b>Six cases were detected with fetal chromosomal abnormalities by high-flux sequencing analysis, among which five were confirmed by karyotyping to be chromosomal aneuploidies (47,XYY; 45,X; 47,XY,+18; 47,XY,+21 and 47,XY,+13), 1 case was confirmed to be structural rearrangement, i.e., 46,XY,der(13;21)(q10;q10),+21. Furthermore, 3 chromosomal polymorphisms (one 46,XY,21p+ and two 46,XY,Yqh-) were identified. The two methods yielded similar results on fetal chromosome copy number detection.</p><p><b>CONCLUSION</b>High-flux sequencing analysis of free DNA derived from maternal plasma is efficient for detecting fetal chromosomal aneuploidies, and is non-invasive, highly sensitive and specific. It therefore has a broad application in antenatal diagnosis.</p>