Prenatal diagnosis and genetic counseling of a Chinese family with inherited multiple chromosomal microduplications.

Background: Copy number variants (CNVs) are an important source of normal and pathogenic genome variations. Chromosomal microdeletions and microduplications have long been associated with abnormal developmental outcomes. Recently, the application of CNV sequencing (CNV-seq) is rapidly identifying new recurrent microdeletion and microduplication syndromes and a previously unsuspected level of copy number variation which needs to be distinguished from pathogenic change.

Materials and methods: In this research, a 26-year-old, gravida 1, para 0, woman underwent amniocentesis at 18 weeks of gestation. Cytogenetic analysis of the cultured amniocytes and CNV-seq on uncultured amniocytes was performed. After that, we performed trio whole-exome sequencing (WES) on the family.

Results: CNV-seq detected three chromosomal microduplications in the fetus, respectively are 2p16.1p15, 6q27, and 9p22.3. The microduplication of 2p16.1p15 is inherited from the mother, and the microduplication of 6q27 and 9p22.3 comes from the father. After genetic counseling, the parents decided to continue the pregnancy.

Conclusion: We present a rare case of a Chinese family with inherited multiple chromosomal microduplications with normal phenotype. Our case can be helpful for prenatal diagnosis and genetic counseling. Chromosomal microdeletions and microduplications are difficult to detect by conventional cytogenetics. Combination of prenatal ultrasound, karyotype analysis, CNV-seq, trio-WES, and genetic counseling is helpful for the prenatal diagnosis of chromosomal microdeletions/microduplications.