Noninvasive Prenatal Diagnosis Of Fetal RhD Status And Fetal FGFR3 Mutation Using MALDI-TOF MS

Background RhD incompatibility between a pregnant woman and her fetus can result in haemolytic disease of the fetus and newborn (HDFN) in subsequent pregnancies. The disease can range from asymptomatic mild anaemia to hydrops or stillbirth associated with severe anaemia and jaundice. Therefore, identification of fetal RhD genotype plays an important role in preventing hemolytic disease.Objective To establish a method for noninvasive prenatal diagnosis of fetal RHD genotyping from RhD-negative women based on matrix-assisted laser ionization time of flight mass spectrometry(MALDI-TOF MS).Methods RhD negative pregnant women with single fetus (20～40 gestational weeks) in the General Hospital of People’s Liberation Army and Beijing Obstetrics and Gynecology Hospital were recruited from August 2013 to March 2015. Fetal RhD genotype was detected by MALDI-TOF MS targeting exon 4,5,7,10 and RHD 1227A to predict the fetal RhD status. A double blind trial was carried out to compare the results of fetal RhD detected by MALDI-TOF MS and serological tests on cord blood.Results A total of 40 plasma samples were collected from RhD-negative pregnant women.Fetal RhD genotype was detected by MALD-TOF MS targeting RHD exon 4,5,7,10 and RHD1227A.38 cases were identified RhD positive when one case was typed RhDel and one was RhD-negative. Five neonatal blood samples couldnot be obtained due to loss to follow up, and the remaining 35 genotypings were in concordance with newborn D phenotypes at delivery.Conclusion These preliminary results demonstrate the feasibility of noninvasive prenatal diagnosis of fetal RhD status from RhD-negative maternal plasma in Chinese population using MALDI-TOF mass spectrometry.Background Achondroplasia (ACH) is the most common form of short-limbed in humans. The phenotypic characteristics of ACH do not manifest until later in pregnancy, which undoubtedly increase the difficulty of diagnosis. More than 98% of the patients have a c.1138 G>A mutation, which make genetic diagnosis possible.Objective To develop a noninvasive method for early prenatal screening for fetal achondroplasia based on MALDI-TOF MS.Methods Three cases were referred to the Department of Obstetrics and Gynecology, Chinese PLA general Hospital for suspected skeletal dysplasia from February 2014 to March 2015. Blood samples were collected from each parent.Their FGFR3 mutations were determined by Sanger sequencing.Suspected fetal karyotype analysis was carried out. With the exclusion of chromosomal abnormalities, fetal FGFR3 mutations were detected by MALDI-TOF MS. The pathogenic variants in suspected fetuses would be confirmed by Sanger sequencing.Results Fetal karyotypes were normal. MALDI-TOF MS showed in these three families with unaffected parents, two may have a de novo c.1138 G>A mutation fetus and one no c.1138 G>A mutation. The Sanger sequencing of family tree were carried out to identify the pathogenic variants.ConclusionNoninvasive prenatal diagnosis of fetal achondroplasia using MALDI-TOF MS can provide genetic screening for fetal achondroplasia by support of a large amount of clinical samples.