The importance of mutation pattern in pregnancy outcomes of patients with abnormal prenatal chromosomal microarray results

Microarray analysis provide more detailed results for prenatal diagnosis over traditional karyotyping. However, variants with uncertain pathogenicity make prenatal genetic counseling more challenging. We analyzed 1560 patients who underwent prenatal single-nucleotide polymorphism (SNP) array analysis at the National Taiwan University Hospital between 2015 and 2020. The parental blood samples from the positive array cases were assessed. Eighty cases were diagnosed with aneuploidy and copy number variants (CNVs). Of the fetuses with prenatally diagnosed trisomy 17.4% were delivered, while the delivery rate of microdeletion and microduplication group were 63.6% and 82.35%. There was a higher delivery rate in patients with inherited mutation than de-novo mutation in the microdeletion group (p = 0.004), while there was no association between these characteristics in the microduplication group (p = 0.214). A dosage variant of 22q11.21 was the most detected variant and accounted for 15% of all abnormal cases. No correlation was identified among birth weight, gestational age, and CNV size in the three common CNV groups (15q11.2, 22q11.21 microdeletion, and 22q11.21 microduplication). The mutation pattern could be one of the factors affecting the parents’ decision for the pregnancy continuation of fetuses with abnormal SNP array results.