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Prenatal diagnosis of a de novo tetrasomy 15q24.3-25.3: Case report and literature review.

ABSTRACT: BACKGROUND:Terminal duplication on chromosome 15q is a rare chromosomal variation. Affected individuals show similar features such as growth dysplasia or the development of frontal bossing, body deformities, facial abnormalities, and genitourinary or cardiovascular disorders. However, it is not yet clear whether such 15q repeats lead to identifiable patterns of clinical abnormalities. Therefore, the purpose of this study was to analyze the prenatal diagnostic results and clinical manifestations of a fetus with 15q duplication and to summarize the literature. METHODS:The case was a fetus at 28 weeks of gestation. The risk of Down syndrome from second-trimester screening was 1/140. Prenatal ultrasound and amniocentesis were performed, and chromosomal microarray analysis (CMA) was used for genetic analysis. RESULTS:The fetus had abnormal clinical features, including intracardiac echogenic focus in the left ventricle, an aberrant right subclavian artery, and growth delay. The fetal chromosomal karyotype was 46,XX,15q?,12q?,21pstk+, and CMA revealed a 10.163 Mb duplication at 15q24.3-q25.3. The couple chose to terminate the pregnancy after careful consideration. CONCLUSIONS:The combination and rational application of cytogenetics technology and molecular genetics technology such as CMA will open up the field of clinical application and provide useful genetic counseling for parents of fetuses carrying such chromosomal duplications.

SUBMITTER: Hu X

PROVIDER: S-EPMC7370735 | biostudies-literature | 2020 Jul

REPOSITORIES: biostudies-literature

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Prenatal diagnosis of a de novo tetrasomy 15q24.3-25.3: Case report and literature review.

Hu Xiaonan X Li Leilei L Zhang Hongguo H Hu Zhuming Z Li Linlin L Sun Meiling M Liu Ruizhi R

Journal of clinical laboratory analysis 20200317 7

<h4>Background</h4>Terminal duplication on chromosome 15q is a rare chromosomal variation. Affected individuals show similar features such as growth dysplasia or the development of frontal bossing, body deformities, facial abnormalities, and genitourinary or cardiovascular disorders. However, it is not yet clear whether such 15q repeats lead to identifiable patterns of clinical abnormalities. Therefore, the purpose of this study was to analyze the prenatal diagnostic results and clinical manifes ...[more]

PMID: 32185823

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Project description:Partial tetrasomy of distal 13q has a reported association with a variable phenotype including microphthalmia, ear abnormalities, hypotelorism, facial dysmorphisms, urogenital defects, pigmentation and skin defects, and severe learning difficulties. A wide range of mosaicism has been reported, which may, to some extent, account for the variable spectrum of observed phenotypes. We report here a pregnancy conceived using intrauterine insemination in a 32-year-old female with a history of infertility. Non-invasive prenatal screening (NIPS) was performed in the first trimester which reported an increased risk for trisomy 13. Follow-up cytogenetic workup using chorionic villus sampling (CVS) and amniotic fluid samples showed a mosaic karyotype with a small supernumerary marker chromosome (sSMC). Chromosomal microarray analysis (CMA) identified a mosaic 31.34 Mb terminal gain on chr13q31.1q34 showing the likely origin of the sSMC to distal chromosome 13q. Follow-up metaphase FISH testing suggested an inverted duplication rearrangement involving 13q31q34 in the marker chromosome and the presence of a neocentromere. At 21 months of age, the proband has a history of gross motor delay, hypotonia, left microphthalmia, strabismus, congenital anomaly of the right optic nerve, hemangiomas, and a tethered spinal cord. Postnatal chromosome analyses in buccal, peripheral blood, and spinal cord ligament tissues were consistent with the previous amniocentesis and CVS findings, and the degree of mosaicism varied from 25 to 80%. It is often challenging to pinpoint the chromosomal identity of sSMCs using banding cytogenetics. A combination of low-pass genome sequencing of cell-free DNA, chromosomal microarray, and FISH enabled the identification of the precise chromosomal rearrangement in this patient. This study adds to the growing list of clinically identified neocentric marker chromosomes and is the first described instance of partial tetrasomy 13q31q34 identified in a mosaic state prenatally. Since NIPS is now being routinely performed along with invasive testing for advanced maternal age, an increased prenatal detection rate for mosaic sSMCs in otherwise normal pregnancies is expected. Future studies investigating how neocentromeres mediate gene expression changes could help identify potential epigenetic targets as treatment options to rescue or reverse the phenotypes seen in patients with congenital neocentromeres.

Dataset Information

Prenatal diagnosis of a de novo tetrasomy 15q24.3-25.3: Case report and literature review.

Publications

Prenatal diagnosis of a de novo tetrasomy 15q24.3-25.3: Case report and literature review.

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