Abstract
BackgroundThe noninvasive prenatal diagnosis procedures that are currently used to detect genetic diseases do not achieve desirable levels of sensitivity and specificity. Recently, fetal methylated DNA biomarkers in maternal peripheral blood have been explored for the noninvasive prenatal detection of genetic disorders. However, such efforts have covered only chromosomal aneuploidy, and fetal methylated DNA biomarkers in maternal whole blood for detecting single-gene diseases remain to be discovered.MethodsTo address this issue, we systematically screened significantly hypermethylated genes in fetal tissues and compared them with maternal peripheral blood potential in an attempt to detect fetal genes in maternal peripheral blood. First, the methylated-CpG island recovery assay combined with a CpG island array was performed for four fetus-toward placental tissues and the corresponding maternal peripheral bloods. Subsequently, direct bisulfite sequencing and combined bisulfite restriction analysis (COBRA) were carried out to validate the methylation status of the hypermethylated genes that were identified by the microarray analysis.ResultsThree hundred and ten significantly hypermethylated genes in the placental tissues were detected by microarray. From the top 15 hypermethylated genes detected by microarray, two were selected for sequencing validation in placental tissue and chorionic villus samples and four were selected for COBRA validation in four placental tissues, ten amniotic fluids and five chorionic villus samples. The six selected genes were confirmed to be hypermethylated in placental tissue and chorionic villus samples, but methylation of the genes could not be detected in the amniotic fluids.ConclusionsOf the many hypermethylated genes and methylation sites that were found in the fetal tissues, some have great potential to be developed into molecular markers for noninvasive prenatal diagnosis of monogenic disorders. Further clinical studies are warranted to confirm these findings.
Highlights
The noninvasive prenatal diagnosis procedures that are currently used to detect genetic diseases do not achieve desirable levels of sensitivity and specificity
Four of the pairs were randomly selected for microarray analysis and combined bisulfite restriction analysis (COBRA); the three other pairs were used to confirm the bisulfite sequencing
We identified a large number of hypermethylated genes in fetal tissues; most of these genes have been recorded in the Online Mendelian Inheritance in Man (OMIM) database where the relationship between abnormalities in these genes and diseases has been defined
Summary
The noninvasive prenatal diagnosis procedures that are currently used to detect genetic diseases do not achieve desirable levels of sensitivity and specificity. Definitive prenatal diagnosis of genetic diseases usually requires obtaining fetal genetic material by invasive procedures such as amniocentesis, chorionic villus sampling and cordocentesis These invasive procedures put the fetus at a small but significant risk and, are carried out only when the risk of abnormal pregnancy, estimated by maternal age, ultrasonography and other noninvasive methods, outweighs the risk of miscarriage caused by such procedures [1]. Noninvasive procedures are available for prenatal diagnosis These procedures use maternal periphery blood samples and quantify maternal serum proteins that are surrogate markers of the underlying genetic abnormality. Such noninvasive diagnostic procedures do not achieve the desirable levels of sensitivity and specificity, and they are not definitive [2]. Great efforts have been made in the last decade to develop fetal molecular biomarkers for noninvasive prenatal diagnosis
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
