ABSTRACT
OBJECTIVE@#To explore the genetic etiology of 5 cases of monochorionic-diamniotic (MCDA) with genetic discordance.@*METHODS@#148 cases of MCDA twins who were diagnosed by amniocentesis at the Maternal and Child Health Care Hospital of Guangxi Zhuang Autonomous Region from January 2016 to June 2020 were selected as the study subjects. Relevant clinical data of the pregnant women were collected, and amniotic fluid samples of the twins were collected separately. Chromosomal karyotyping analysis and single nucleotide polymorphism array (SNP array) assay were carried out.@*RESULTS@#The results of chromosomal karyotyping analysis showed that 5 of the MCDA twins had inconsistent chromosome karyotypes, with an incidence of 3.4% (5/148). SNP array assay showed that 3 fetuses were mosaics.@*CONCLUSION@#Genetic discordance occurs among MCDA twins, and prenatal counseling for such cases should be given by doctors with experience in medical genetics and fetal medicine, and personalized clinical management should be recommended.
Subject(s)
Child , Pregnancy , Female , Humans , China , Twins/genetics , Amniocentesis , Karyotyping , Fetus , Twins, Monozygotic/genetics , Ultrasonography, Prenatal , Retrospective StudiesABSTRACT
Objective:To explore the genetic background in monochorionic diamniotic (MCDA) twins discordant for karyotypes.Methods:This study retrospectively analyzed four pregnant women who were diagnosed as having MCDA twins with prenatal diagnostic indications by ultrasound at Maternity and Child Health Care of Guangxi Zhuang Autonomous Region from January 2016 to December 2019. Dual amniocentesis was performed for all cases guided by ultrasound and the twin amniotic fluids were taken for karyotyping and single nucleotide polymorphism (SNP) array testing. Zygosity was determined by SNP genotype analysis.Results:The karyotypes of four MCDA twins were 47,XX,+18 and 46,XX, 45,X and 46,XX, 47,XXY[17]/46,XY[33] and 47,XXY, and 47,XX,+21 and 46,XX, respectively. The results of SNP were arr(18)×3 and arr(1-22,X)×2, arr(X)×1 and arr(1-22,X)×2, arr(X)×1~2,(Y)×1 and arr(X)×2,(Y)×1, arr(21)×3 and arr(21)×2~3. All of them were monozygotic twins according to the SNP genotypes. Three out of the four cases chose to terminate the pregnancy due to fetal chromosomal abnormalities and one was lost to follow-up. One gave birth to a healthy child in the next pregnancy.Conclusions:Clinicians should be alert to the discordant karyotypes in MCDA twins, of which the mechanism is yet to be explored.