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Unusual twinning: Additional findings during prenatal diagnosis of twin zygosity by single nucleotide polymorphism (SNP) array
Author(s) -
Zou Zhiyong,
Huang Linhuan,
Lin Shaobin,
He Zhiming,
Luo Yanmin
Publication year - 2018
Publication title -
prenatal diagnosis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.956
H-Index - 97
eISSN - 1097-0223
pISSN - 0197-3851
DOI - 10.1002/pd.5255
Subject(s) - zygosity , uniparental disomy , biology , genetics , single nucleotide polymorphism , twin pregnancy , monozygotic twin , dizygotic twin , snp array , snp , obstetrics , twin study , fetus , pregnancy , karyotype , medicine , chromosome , genotype , heritability , gene
Objective To evaluate the incidence and characteristics of unusual twinning by using single nucleotide polymorphism (SNP) array to identify twin zygosity. Methods This study reviewed 386 twin pairs who were seen for prenatal or postnatal diagnosis and underwent SNP array to detect zygosity. Results The incidence of monozygotic (MZ) twins was 11.36% (25/220) in the assisted reproductive technology (ART)‐conceived group. Monochorionic dizygotic twins represented 3 of 24 monochorionic ART‐conceived twin pairs (3/24, 12.50%) but none in the spontaneous twin pairs. Among 4 single‐embryo transfer twin pairs, 3 represented unusual twinning, including 2 MZ twin pairs with discordant karyotypes and 1 dizygotic twin pair of the same gender. Of the pregnancies with 2 or more embryos transferred, 7.77% (15/193) were MZ. Additionally, there was a dichorionic monozygotic twin pair with placental vascular anastomoses from a day‐5 blastocyst transfer. Conclusion Single nucleotide polymorphism array can provide zygosity diagnosis in addition to chromosomal copy number variation and uniparental disomy detection. ART twin pregnancies have a risk of unusual twinning, such as monochorionic dizygotic, single‐embryo transfer twin pairs with discordant karyotypes or dizygotic, and dichorionic monozygotic with vascular anastomoses from day‐5 transfer.