Prenatal diagnosis and postnatal followup of partial trisomy 13q and partial monosomy 10p: a case report and review of the literature

Partial Trisomy 13q/Monosomy 3p Resulting from a Paternal Reciprocal 3p;13q Translocation in a Boy with Facial Dysmorphism and Hypertrophic Cardiomyopathy

Individuals with 3p deletion show a great clinical variability. Apparently, a 1.5-Mb terminal deletion, including the CRBN and CNTN4 genes, is sufficient to cause this syndrome. Partial trisomy 13q is a rare chromosomal abnormality with a variable phenotypic expression, but in most cases, patients have a phenotype resembling complete trisomy 13. The aim of the present study is to describe a 9-month-old Mexican male patient with 3p deletion/13q duplication and a novel clinical finding. He presented with facial dysmorphism and multiple congenital alterations. Echocardiogram revealed cardiac insufficiency with hypertrophic cardiomyopathy and pulmonary hypertension, not previously reported. Karyotype from the patient and his father were 46,XY,add(3)(p26) and 46,XY,t(3;13), respectively. Microarray assay of the proband exhibited an approximately 2.6-Mb loss at terminal 3p26.3 and a 27.7-Mb gain of the long arm in terminal chromosome 13 at q31.1q34. A chromosomal imbalance with a partial trisomy 13q31.1q34 and monosomy 3p26.3 of paternal origin were detected. Microarray assay of both parents were normal. The proband has a cardiomyopathy not previously reported. These data enrich the spectrum of clinical manifestations in 3p deletion/3q duplication chromosomopathy.

Detection of cytogenomic abnormalities by OncoScan microarray assay for products of conception from formalin-fixed paraffin-embedded and fresh fetal tissues

Background

The OncoScan microarray assay (OMA) using highly multiplexed molecular inversion probes for single nucleotide polymorphism (SNP) loci enabled the detection of cytogenomic abnormalities of chromosomal imbalances and pathogenic copy number variants (pCNV). The small size of molecular inversion probes is optimal for SNP genotyping of fragmented DNA from fixed tissues. This retrospective study evaluated the clinical utility of OMA as a uniform platform to detect cytogenomic abnormalities for pregnancy loss from fresh and fixed tissues of products of conception (POC).

Results

Fresh specimens of POC were routinely subjected to cell culture and then analyzed by karyotyping. POC specimens with a normal karyotype (NK) or culture failure (CF) and from formalin-fixed paraffin-embedded (FFPE) tissues were subjected to DNA extraction for OMA. The abnormality detection rate (ADR) by OMA on 94 cases of POC-NK, 38 cases of POC-CF, and 35 cases of POC-FFPE tissues were 2% (2/94), 26% (10/38), and 57% (20/35), respectively. The detected cytogenomic abnormalities of aneuploidies, triploidies and pCNV accounted for 50%, 40% and 10% in POC-CF and 85%, 10% and 5% in POC-FFPE, respectively. False negative result from cultured maternal cells and maternal cell contamination were each detected in one case. OMA on two cases with unbalanced structural chromosome abnormalities further defined genomic imbalances and breakpoints.

Conclusion

OMA on POC-CF and POC-FFPE showed a high diagnostic yield of cytogenomic abnormalities. This approach circumvented the obstacles of CF from fresh specimens and fragmented DNA from fixed tissues and provided a reliable and effective platform for detecting cytogenomic abnormalities and monitoring true fetal result from maternal cell contamination.

Inverted duplication, triplication and quintuplication through sequential breakage-fusion-bridge events induced by a terminal deletion at 5p in a case of spontaneous abortion

Background

Integrated chromosome, fluorescence in situ hybridization (FISH) and array comparative genomic hybridization (aCGH) analyses have been effective in defining unbalanced chromosomal rearrangements. Discordant chromosome and aCGH results are rarely reported.

Methods

Routine cytogenomic analyses and literature review were performed in the study of a case from products of conception (POC).

Results

Chromosome and FISH analysis revealed a mosaic pattern consisting of a primary aberration of an inverted duplication of 5p and derived secondary and tertiary aberrations from sequential triplication and quintuplication of 5p, respectively. The aCGH analysis detected only a 1.521 Mb terminal deletion at 5p15.33 with no other pathogenic copy number variants in the genome. This mosaic karyotypic pattern likely resulted from chromosome instability induced by sequential breakage‐fusion‐bridge events during in vitro cell culture. A review of literature found heterogeneous distal deletion and inverted duplication of 5p in prenatal and pediatric cases.

Conclusion

This is the first case reported in POC with a unique mosaic pattern and discordant chromosome and aCGH results. Caution should be applied in reporting and interpreting these discordant results and further analysis for underlying mechanism should be considered.

Integrated FISH, Karyotyping and aCGH Analyses for Effective Prenatal Diagnosis of Common Aneuploidies and Other Cytogenomic Abnormalities

Current prenatal genetic evaluation showed a significantly increase in non-invasive screening and the reduction of invasive diagnostic procedures. To evaluate the diagnostic efficacy on detecting common aneuploidies, structural chromosomal rearrangements, and pathogenic copy number variants (pCNV), we performed a retrospective analysis on a case series initially analyzed by aneuvysion fluorescence in situ hybridization (FISH) and karyotyping then followed by array comparative genomic hybridization (aCGH). Of the 386 cases retrieved from the past decade, common aneuploidies were detected in 137 cases (35.5%), other chromosomal structural rearrangements were detected in four cases (1%), and pCNV were detected in five cases (1.3%). The relative frequencies for common aneuploidies suggested an under detection of sex chromosome aneuploidies. Approximately 9.5% of cases with common aneuploidies showed a mosaic pattern. Inconsistent results between FISH and karyotyping were noted in cases with pseudo-mosaicism introduced by culture artifact or variable cellular proliferation from cells with mosaic karyotypic complements under in vitro cell culture. Based on findings from this case series, cell-based FISH and karyotyping should be performed to detect common aneuploidies, structural chromosomal abnormalities, and mosaic pattern. DNA-based aCGH and reflex FISH should be performed to detect and confirm genomic imbalances and pCNV. Practice points to ensure the diagnostic accuracy and efficacy were summarized.

Prenatal Detection and Postnatal Follow-Up of Segmental Aneusomies of Chromosome 13 in 4 Consecutive Pregnancies in an Ethnic South Indian Family With a Maternally Inherited Balanced Translocation

OBJECTIVE

To assess the postnatal clinical manifestation of an antenatally detected unbalanced rearrangement involving chromosome 13 in an ethnic South Indian couple.

METHODS

We used conventional cytogenetics on fetal cells obtained from prenatal specimens and on peripheral blood lymphocytes from consanguineous family members to ascertain the chromosomal abnormalities.

RESULTS

We report the reproductive outcomes of a maternally inherited chromosome translocation involving chromosome 9 and 13 and the informed decisions of the couple, after genetic counseling in India, regarding their 4 pregnancies.

CONCLUSION

This case report highlights the current practice in India of offering prenatal diagnosis and preimplantation genetic diagnosis to individuals who are carriers of balanced translocations, to reduce the risk of conceiving chromosomally abnormal offspring.

A novel (paternally inherited) duplication 13q31.3q32.3 in a 12-year-old patient with facial dysmorphism and developmental delay

We report a 12-year-old boy referred to the Clinical Genetics service in view of facial dysmorphism, learning difficulties and autistic spectrum disorder. 60K arrayCGH revealed an 8.2-Mb duplication on chromosome 13q31.3q32.3, which was paternally inherited. This specific duplication on chromosome 13 has not been previously reported in the medical literature, and there are no familial or de novo patients with the same duplication breakpoints. This region contains 24 OMIM genes, including the glypicans GPC5 and GPC6, and the ZIC2 gene. We discuss the relevance of this chromosome imbalance and discuss the impact of this duplication on our patient's phenotype. Given that the duplication on 13q was paternally inherited, and although initially thought to be of uncertain significance, on exploring the family history further, it became apparent that the father had learning difficulties as a child and previous surgery for congenital diaphragmatic hernia. Here we explore the phenotype in association with this novel duplication on chromosome 13q and add to the existing literature on array findings within this region.