ABSTRACT
A 44-year-old pregnant woman (G5P3) who had delivered two children with DMD was admitted and underwent prenatal diagnosis at Peking Union Medical College Hospital in 2019. (1) The karyotype of the fetus in 2019 was 47,XXY. The fluorescence in situ hybridization (FISH) result showed a nucish(CSPX×2, CSPY×1)[100] and multiplex ligation-dependent probe amplification (MLPA) suggested sex chromosome abnormality. Based on the above results, the fetus was diagnosed with Klinefelter syndrome. Fetal short tandem repeat (STR) linkage analysis and Sanger sequencing indicated a heterozygous mutation of c.9543delG(p.Trp3181CysfsTer2). (2) Sanger sequencing of the proband found a novel frameshift mutation of c.9543delG(p.Trp3181CysfsTer2 ) in exon 65 of the DMD gene. (3) The male fetus performing prenatal diagnosis in 2008 was found to have the same maternal gene markers as the proband with the same genotype. While the genotype of the fetus in 2009 obtained a different maternal gene marker from the proband and did not detect the same DMD gene mutation. This fetus was delivered at full term and was good during follow-up. (4) The elder brother and cousin of the proband had the same frameshift mutation in exon 65 of the DMD gene as the proband. The mother of the proband was a heterozygous carrier of the mutation.
ABSTRACT
Objective:To investigate the impact of maternal X chromosome aneuploidies on cell free DNA (cf-DNA) prenatal screening.Methods:After genetic counseling, invasive prenatal diagnosis was provided for the 124 cases with high risk of sex chromosome aneuploidie (SCA) indicated by cf-DNA prenatal screening. For cases with discordant results of fetal prenatal diagnosis and cf-DNA prenatal screening, maternal leukocyte was collected for copy number variation sequencing (CNV-seq) to detect whether the maternal X chromosome was carrying variations.Results:Totally, 124 cases with high risks of SCA indicated by cf-DNA prenatal screening, 9 cases refused to take invasive prenatal diagnosis, while the remaining 115 cases received. Among the 115 cases, 41 cases received accordant results with cf-DNA prenatal screening while 74 cases discordant. Among the 74 cases with discordant results, 19 cases were indicated with maternal X chromosome variations by maternal leukocyte CNV-seq, which accounting for 25.7% (19/74) of the SCA false positive cases, and 15.3% (19/124) of all SCA cases.Conclusions:Pregnant women with X chromosome variations may affect the results of cf-DNA prenatal screening, resulting in false positive or false negative outcomes, it should be emphasized that the cf-DNA results may be affected by maternal X chromosome variations. In cases with discordant results of prenatal diagnosis and cf-DNA prenatal screening, maternal leukocyte CNV-seq is recommended to find the reasons of false positive or negative results. And cf-DNA prenatal screening is not recommended for pregnant women who are already known with X chromosome variations.
ABSTRACT
Objective@#To investigate the impact of maternal X chromosome aneuploidies on cell free DNA (cf-DNA) prenatal screening.@*Methods@#After genetic counseling, invasive prenatal diagnosis was provided for the 124 cases with high risk of sex chromosome aneuploidie (SCA) indicated by cf-DNA prenatal screening. For cases with discordant results of fetal prenatal diagnosis and cf-DNA prenatal screening, maternal leukocyte was collected for copy number variation sequencing (CNV-seq) to detect whether the maternal X chromosome was carrying variations.@*Results@#Totally, 124 cases with high risks of SCA indicated by cf-DNA prenatal screening, 9 cases refused to take invasive prenatal diagnosis, while the remaining 115 cases received. Among the 115 cases, 41 cases received accordant results with cf-DNA prenatal screening while 74 cases discordant. Among the 74 cases with discordant results, 19 cases were indicated with maternal X chromosome variations by maternal leukocyte CNV-seq, which accounting for 25.7% (19/74) of the SCA false positive cases, and 15.3% (19/124) of all SCA cases.@*Conclusions@#Pregnant women with X chromosome variations may affect the results of cf-DNA prenatal screening, resulting in false positive or false negative outcomes, it should be emphasized that the cf-DNA results may be affected by maternal X chromosome variations. In cases with discordant results of prenatal diagnosis and cf-DNA prenatal screening, maternal leukocyte CNV-seq is recommended to find the reasons of false positive or negative results. And cf-DNA prenatal screening is not recommended for pregnant women who are already known with X chromosome variations.