Objective To analyze the distribution characteristics of abnormal karyotypes of fetal sex chromosome aneuploidy(SCA)and pregnancy outcomes in 101 fetal cases.Methods A retrospective study was conducted among 7 821 pregnant women who underwent successfully prenatal karyotyping diagnosis at Guangxi Zhuang Autonomous Region People's Hospital from January 2016 to December 2021.All women received amniotic fluid cell culture karyotype analysis and copy number variation sequencing(CNV-seq)detection and 101 cases of SCA detected were analyzed.Results A total of 101 cases were detected by SCA,with a detection rate of 1.29％.Among them,Klinefelter syndrome accounted for 33.66％,superestrogenism syndrome accounted for 17.82％,superandrogenic syndrome accounted for 12.87％,turner syndrome accounted for 10.89％,other aneuploidy abnormalities[including 48,XXXY:1 case;69,XXY(80％)/68,XXY,-22(20％):1 case]accounted for 1.98％,and chimerism accounted for 22.77％.The prenatal indications for 101 cases of SCA were as follows:age ≥ 35 years,high/critical risk of serum biochemical screening,fetal ultrasound abnormalities,abnormalities in non-invasive prenatal testing(NIPT),history of adverse pregnancy and childbirth and other reasons(1 case of cerebral palsy in pregnant women and 4 cases of bilateral thalassemia)accounted for 53.47％(54/101),4.95％(5/101),17.82％(18/101),51.49％(52/101),12.87％(13/101),4.95％(5/101),respectively.Partial cases had multiple prenatal diagnostic indications.Meanwhile,23 fetuses diagnosed with sex chromosome chimerism,of which 22 cases were validated by karyotype and CNV seq,11 pregnant women chose to terminate their pregnancy,with the rest chose to continue pregnancy.Conclusion The combination of prenatal karyotype diagnosis,serological testing,prenatal ultrasound and other prenatal screening methods can help improve the detection rate of SCA,while CNV-seq can provide more clinical evidence for genetic counseling of pregnant women with sex chromosome chimerism.

This paper reported a woman with polycystic kidney disease who had increased fetal nuchal translucency (NT) in her two sequential pregnancies. The fetal NT thickness in the first pregnancy was 5.1 mm at 12 +5 weeks of gestation, and the infant was born prematurely at 32 gestational weeks. However, the baby girl died due to respiratory insufficiency and severe asphyxia. The NT thickness in the present pregnancy was 5.7 mm at 12 weeks of gestation. Whole-exome sequencing (WES) and Sanger sequencing confirmed that the dead infant and the current fetus carried compound heterozygous variants of maternal c.4255_4256del and paternal c.18366+2T>C in NEB gene, both were pathogenic variants. The current fetus was diagnosed with arthrogryposis multiplex congenita 6 (AMC6). After genetic counseling, the pregnant woman chose to terminate the pregnancy. The pregnant woman was diagnosed as having polycystic kidney disease type 1 caused by large deletions in exons 25-43 of PKD1 gene by WES combined with multiplex ligation-dependent probe amplification technology.