Genetic etiology of fetal conotruncal defects and significance of copy number variation sequencing and whole exome sequencing: analysis of 196 cases / 中华围产医学杂志

ABSTRACT

Objective:To investigate the genetic etiology of fetal conotruncal heart defects (CTDs) and to evaluate the performance of copy number variation sequencing (CNV-seq) and whole exome sequencing (WES) in identifying the genetic etiology.Methods:This retrospective study involved 196 fetuses diagnosed with CTDs by fetal echocardiography in Beijing Anzhen Hospital, Capital Medical University from June 2017 to December 2021. CNV-seq was performed to screen for chromosomal abnormalities [aneuploidy and copy number variations (CNVs)] in the fetuses and their parents, and then WES was performed if CNV-seq was negative. The diagnostic yields of genetic abnormalities [aneuploidy+CNVs+single nucleotide variations (SNVs)] for different types of CTDs were compared using Chi-square test. Results:CNV-seq revealed 54 cases (27.6%, 54/196) with chromosomal abnormalities, including 14 (7.1%, 14/196) aneuploidies, 39 (19.9%, 39/196) CNVs and one aneuploidy complicated by CNVs. Together with another 13 fetuses with pathogenic or likely pathogenic SNVs detected by WES among the rest 142 cases whose CNV-seq results were negative, the total detection rate of genetic abnormalities was 34.2% (67/196). WES increased the diagnostic yield for CTDs by 9.2% (13/142). There was significant difference in the diagnostic yields for different types of CTDs ( χ2=20.31, P=0.002). The diagnostic yield was relatively high for interrupted aortic arch of type B, absent of the pulmonary valve -type of tetralogy of Fallot (9/10 and 8/12), but low for transposition of the great arteries (12.5%, 5/40). Conclusions:CNVs are the common genetic abnormalities in fetal CTDs, and SNVs are also detected in some cases. It is recommended that all fetuses with CTDs should undergo genetic testing. CNV-seq should be used in combination with WES if possible to improve the identification of genetic etiology and provide reference for genetic counseling.