Whole exome sequencing in recurrent early pregnancy loss

Semiconductor Sequencing Analysis of Chromosomal Copy Number Variations in Spontaneous Miscarriage

BACKGROUND Array CGH is the criterion standard for identifying copy number variations (CNV), but the restrictive requirement of DNA quality and relatively high cost prevent the use of this method as a general assay in hospitals in developing countries. Our principal objective was to determine whether the semiconductor sequencing platform (SSP) could be an alternative method in CNV detection for spontaneous miscarriage. MATERIAL AND METHODS A total of 443 spontaneous miscarriage samples were collected and subjected to low-coverage (0.1X) whole-genome analysis by SSP. These samples were verified by array CGH and 8 low-quality DNA samples were analyzed by SSP and validated by MLPA. RESULTS SSP detected 195 chromosomal numerical abnormalities, 74 CNVs, and 9 mosaicisms among the 435 samples. Among 74 CNV abnormalities, SSP detected an equal number (56) of CNVs 56 >1 Mb with array CGH. However, SSP missed more 6 cases CNVs <1 Mb than array CGH (12 vs. 18). SSP detected more mosaicisms than array CGH (9 vs. 7, p=0.5). Interestingly, SSP detected the mosaicism which had only 8% X monosomy, which was much lower than the minimal percentage of monosomy that was detected by array CGH. CONCLUSIONS SSP is of equivalent efficacy as array CGH in detecting CNVs >1 Mb, and performs better in identifying mosaicism. With the merits of low cost and less demand of input DNA, SSP is a good alternative for use in genetic diagnosis.

Expression of thioredoxin, 8Hydroxy-deguanosine and peroxiredoxins in placental tissues

In this study we analyzed the expression of 8-hydroxy-deguanosine (8OHdG), thioredoxin (Trx) and peroxiredoxins (Prx) 2, 3, 4, 5 and 6 in 80 cases of placental samples representing both normal and diseased placentas. The staining was evaluated separately in the stromal, trophoblastic and vascular components of the tissues. The results indicate that during the first trimester the level of reactive oxygen species (ROS) as indicated by 8OHdG was highest in the stromal component, which was also the case for Trx, Prx3, Prx4 and Prx6. In diseased placentas stromal 8OHdG was lower in cases with chromosomal aberrations but higher in molar disease in both trophoblastic and stromal cells. In chorioamnionitis stromal prx 5 and prx6 were high. Stromal prx4 and trophoblastic prx6 and stromal and endothelial Trx were also higher in molar disease. The results show that the oxidative stress is high in placentas during the first trimester. This probably reflects the oxidation burst of the placental tissues due to development of vascularity. In diseased placentas elevated levels of Prxs were seen in chorioamnionitis reflecting the ROS stress induced by inflammatory cells. The higher values of antioxidative enzymes in molar disease are possibly due to defective placentation. All in all, the results underline the importance on ROS associated mechanisms in placental development and the function of placenta to protect the developing fetus from harmful effects of reactive oxygen species as evidenced by their abundant expression in different cellular compartments of the placenta.