Dataset Information

A report on seven fetal cases associated with 15q11-q13 microdeletion and microduplication.

ABSTRACT:

Background

The 15q11-q13 region contains three breakpoints (BP1 to BP3), and copy number variations often occur in the region.

Aims

15q11-q13 microdeletion and microduplication are usually associated with Prader-Willi and Angelman syndromes, respectively. It is not yet clear to what extent microdeletion and microduplication affect the physical health of the fetus and the child. In this study, we examined seven fetuses ranging in gestational age from 15 to 27 weeks.

Materials & methods

Detailed prenatal screening and laboratory examinations were performed, while karyotype analysis and chromosomal microarray analysis (CMA) of the amniotic fluid and umbilical cord blood were applied for genetic analysis.

Results

CMA analysis showed that four fetuses harbored a microdeletion and one fetus showed a microduplication at 15q11.2 BP1-BP2, two fetuses had a microdeletion at 15q11-q13 BP2-BP3, and one fetus had an additional microdeletion at 16p13.11.

Discussion

There is no clear standard for the clinical diagnosis of 15q11-q13 microdeletion and microduplication, some of them have clinical phenotypes or are clinically affected.

Conclusion

Therefore, parents of such fetuses should be informed of the possibility of microdeletions or microduplications to mitigate the psychological burden, and medical consultation and assistance should be provided when communicating the results of the mid-gestation screening.

SUBMITTER: Huang X

PROVIDER: S-EPMC8104164 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Project description:BackgroundSmall supernumerary marker chromosomes (sSMCs) are common structurally abnormal chromosomes that occur in 0.288% of cases of mental retardation. Isodicentric 15 (idic(15)) is common in sSMCs and usually leads to a rare chromosome disorder with distinctive clinical phenotypes, including early central hypotonia, developmental delay, epilepsy, and autistic behavior. It was previously shown that the partial tetrasomy 15q and partial hexasomy 15q syndromes are usually caused by one and two extra idic(15), respectively. Karyotypes containing a mosaic partial octosomy 15q resulting from three extra idic(15) have rarely been reported.Case presentationTwo patients with profound intellectual impairment, development delay and hyperpigmentation were recruited for this study. The phenotype was relatively more severe in patient 1 than in patient 2. Conventional cytogenetic analysis of peripheral blood obtained from patients 1 and 2 revealed rare mosaic karyotypes containing sSMCs, i.e., mos 49,XX,+mar × 3[83]/48,XX,+mar × 2[7]/46,XX[10] and mos 48,XX,+mar × 2[72]/47,XX,+mar[28], respectively. The results of analyses of copy number variation (CNV) and fluorescence in situ hybridization (FISH) analyses, showed that the sSMCs were found to be idic(15) involving the Prader-Willi/Angelman Syndrome Critical Region (PWACR) genes and the P gene, with duplication sizes of 6.3 Mb and 9.7 Mb, respectively. DNA fingerprinting analysis of patient 1 showed a maternal origin for the idic(15). Both patients had mosaic idic(15) karyotypes: patient 1 had cells with a 15q partial octosomy (83%), and patient 2 had cells with a 15q partial hexasomy (72%).ConclusionsWe detected two rare mosaic idic(15) karyotypes that were associated with congenital abnormalities, including a rare mosaic octosomy of 15q11-q13. Our cases further validate the notion that the phenotypic severity is correlated with the level of mosaicism and the dosage effect of related genes in the proximal 15q.