SNP-chip technology for identification of origins for prenatally detected marker chromosomes / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To determine the origin of 1 prenatally detected small supernumerary marker chromosome (sSMC) using SNP-chip technology, and to deduce the underlying mechanism.</p><p><b>METHODS</b>The fetal sample was subjected to karyotype analysis. The identified sSMC was subjected to genom wide scan using a SNP microarray chip. The results were validated with fluorescence in situ hybridization (FISH).</p><p><b>RESULTS</b>The karyotype of the fetus was determined as 46, X, +mar, which was verified by SNP microarray chip analysis as Yp11.2-11.3 duplication, along with loss of Yq11.2 region, FISH analysis has confirmed that the sSMC has derived from the Y chromosome.</p><p><b>CONCLUSION</b>The karyotype of the fetus was determined as 46, X, idic(Y) (pter→ p11.2::11.2→ pter). Regional deletion of Yq11.2 has been associated with male azoospermia. SNP chip analysis can exclude minor deletions and duplications with a size of more than 1 Mb, which may be applied for verifying difficult cases as well as microdeletion and duplication syndromes upon prenatal diagnosis.</p>

Rapid and high-throughput multiplex ligation-dependent probe amplification for diagnosis of chromosome aneuploidy / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To assess the diagnostic value of multiplex ligation-dependent probe amplification (MLPA) for detection of common chromosome aneuploidy in amniotic fluid (AF) cells in order to obtain an accurate, rapid, cost-effective and high-throughput method in routine prenatal clinical practice.</p><p><b>METHODS</b>The MLPA test was performed on 500 AF samples by using kit P095 and the results were obtained by using analysis software RH-MLPA-v511. The results were compared with that from fluorescence in situ hybridization (FISH) and traditional karyotyping (TK). The technical critical issues were analyzed in routine diagnostic application.</p><p><b>RESULTS</b>The absolute specificity and sensitivity of the MLPA test to detect the aneuploidy were 100%. For the 500 AF samples, the success rate of the MLPA tests was 97%. Among them 92% were finished within three working days and 5% required more days for repeating. The test failure rate was 3%. The results confirmed that for the 38 detectable aneuploid samples, the probe reliability weighted mean ratio values were more than 4SD compared to normal diploids and the 2 suspected trisomy samples were more than 2SD. In this study, authors analyzed hybridization efficiencies of 8 probes for chromosome 21, and the presence of a trisomy was considered if at least 4 of the 8 probes gave probe ratio of >1.3.</p><p><b>CONCLUSION</b>Thedata suggested that MLPA is a rapid, simple and reliable method for large scale testing for aneuploidy of chromosomes 13, 18, 21, X, or Y in AF. The MLPA technology is complementary to AF culture and valuable for prenatal diagnosis.</p>