Objective: To carry out prenatal diagnosis for a fetus with normal ultrasonographic finding at 20 weeks' gestation but a copy number variant(CNV) of 13q indicated by non-invasive prenatal test (NIPT).
Methods: Karyotyping analysis and chromosomal CNV assay were carried out on the amniotic fluid sample. Parental peripheral blood sample was collected for chromosomal analysis. Detailed fetal ultrasound scan was carried out to rule out structural abnormalities of the fetus.
Results: The fetus was detected with a heterozygous 10.14 Mb deletion at 13q21.1q21.32, which has originated from the phenotypically normal mother. No apparent karyotypic abnormality was detected in the fetus and its parents. No ultrasonic abnormality was found in the fetus.
Conclusion: Both the fetus and its mother have carried a heterozygous 10.14 Mb deletion at 13q21.1q21.32 and presented normal phenotypes.Combined with literature review, the segmental deletion was judged to be a benign variant.