Abstract
BackgroundNearly 9.89% of chromosome 16 consists of segmental duplications, which makes it prone to non-homologous recombination. The present study aimed to investigate the incidence and perinatal characteristics of submicroscopic chromosome 16 aberrations in prenatal diagnosis.ResultsA total of 2,414 consecutive fetuses that underwent prenatal chromosomal microarray analysis (CMA) between January 2016 and December 2018 were reviewed. Submicroscopic anomalies of chromosome 16 accounted for 11.1% (15/134) of all submicroscopic anomalies detected in fetuses with normal karyotype, which was larger than the percentage of anomalies in any other chromosome. The 15 submicroscopic anomalies of chromosome 16 were identified in 14 cases; 12 of them had ultrasound abnormalities. They were classified as pathogenic (N = 7), and variants of uncertain significance (N = 8). Seven fetuses with variants of uncertain significance were ended in live-born, and the remaining were end in pregnancy termination.ConclusionSubmicroscopic aberrations of chromosome 16 are frequent findings in prenatal diagnosis, which emphasize the challenge of genetic counseling and the value of CMA. Prenatal diagnosis should lead to long-term monitoring of children with such chromosomal abnormalities for better understanding of the phenotype of chromosome 16 microdeletion and microduplication syndromes.
Highlights
9.89% of chromosome 16 consists of segmental duplications, which makes it prone to nonhomologous recombination
Copy number variants (CNVs) of chromosome 16 ranged from 600 kb to 2.24 Mb in size (Table 1)
Microduplications of 16p13.11 usually have incomplete penetrance and/or variable expression. They mainly manifest as cognitive impairment, behavioral disorders, congenital heart defects, and skeletal malformations, that CNV may not have been the reason for Urorectal Septum Malformation Sequence (URSMS)
Summary
9.89% of chromosome 16 consists of segmental duplications, which makes it prone to nonhomologous recombination. The present study aimed to investigate the incidence and perinatal characteristics of submicroscopic chromosome 16 aberrations in prenatal diagnosis. It is well known that complete trisomy 16 is embryonic lethal, and it is the most common autosomal anomaly revealed by genetic diagnosis of spontaneous miscarriage [1]. LCR16a, a 20 Kb low-copy repeat sequence, is the most frequent chromosome-specific duplication distributed in multiple locations over the entire length of chromosome 16 in a non-tandem manner. Most of it is concentrated on the short arm, including cytogenetic band locations 16p13.3, 16p13.1, 16p12.3, 16p12.2, 16p11, 16q22.2 and 16q23 [3]. This duplication may potentially lead to the rearrangement of the short arm segments of chromosome 16, which explains the high variability in breakpoints and sizes of 16p microdeletions and micro-duplications
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