Dataset Information

Partial trisomy 16q and partial monosomy 7p of a fetus derivated from paternal balanced translocation: A case report.

ABSTRACT:

Introduction

Subchromosomal deletions and duplications could currently be detected by noninvasive preliminary screening (NIPS). However, NIPS is a screening test that requires further diagnosis. Here we report a fetus with an autosomal abnormality revealed by NIPS and conventional karyotype combined with copy number variations sequencing (CNV-seq) confirmed the fetus with an unbalanced translocation.

Patient concern

This was the fourth pregnancy of a 30-year-old woman who underwent 2 spontaneous abortions and gave birth to a child with a normal phenotype. The woman and her husband were healthy and nonconsanguineous. NIPS indicated a repeat of about 19-Mb fragment at the region of 16q22.1-q22.4 at 17-week gestation.

Diagnoses

The combination of traditional karyotype and CNV-seq could better locate the abnormal chromosomal region and further identify the source of fetal chromosomal abnormalities. Simultaneously, we evaluated the fetal morphology by ultrasound examination. The karyotype of the fetus was 46,XX,der(7)t(7;16)(p22;q23) and CNV-seq results showed an approximately 20.96-Mb duplication in 16q22.1-q24.3 (69200001-90160000) and an approximately 3.86-Mb deletion in 7p22.3-p22.2 (40001-3900000). Prenatal ultrasound revealed the fetal micrognathia. The paternal karyotype was 46,XY, t (7;16) (p22;q23), while the maternal was normal. The fetus inherited an abnormal chromosome 7 from its father.

Interventions

No treatment for the fetus.

Outcomes

Pregnancy was terminated.

Conclusions

To our knowledge, the occurrence of de novo partial trisomy 16q (16q22.1-qter) and partial monosomy 7p (7p22.2-pter) has not previously been reported up to now. Here, we present the perinatal findings of such a case and a review of the literatures. CNV-seq combined with karyotype is a useful tool for chromosomal abnormalities indicated by NIPS.

SUBMITTER: Xie HH

PROVIDER: S-EPMC7899829 | biostudies-literature | 2021 Feb

REPOSITORIES: biostudies-literature

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Publications

Partial trisomy 16q and partial monosomy 7p of a fetus derivated from paternal balanced translocation: A case report.

Xie Hui-Hui HH Liu Tong T Zhang Jing-Bo JB Zhai Jing-Fang JF Liu Ying Y

Medicine 20210201 7

<h4>Introduction</h4>Subchromosomal deletions and duplications could currently be detected by noninvasive preliminary screening (NIPS). However, NIPS is a screening test that requires further diagnosis. Here we report a fetus with an autosomal abnormality revealed by NIPS and conventional karyotype combined with copy number variations sequencing (CNV-seq) confirmed the fetus with an unbalanced translocation.<h4>Patient concern</h4>This was the fourth pregnancy of a 30-year-old woman who underwen ...[more]

PMID: 33607772

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Project description:A female patient with a partial trisomy 16q was described previously. Her clinical characteristics included obesity, severe anisomastia, moderate to severe mental retardation, dysmorphic facies, and contractions of the small joints. In this paper, we describe a more detailed analysis of the genetic anomaly in this patient. We were particularly interested in the involvement of the fat mass and obesity associated gene (FTO) in her duplication. Single nucleotide polymorphisms in FTO have recently been associated with obesity. We have precisely mapped the breakpoints of the duplication using high resolution oligonucleotide array comparative genome hybridization (CGH). We found that the duplication spans 11.45 Mb on 16q11.2 to 16q13 and it includes FTO. The increased copy number of FTO was confirmed with a qPCR on genomic DNA of the patient and healthy controls. We investigated the influence of the increased FTO copy number on FTO gene expression in immortalized lymphocytes from the using qPCR. We found no evidence of increased FTO expression in the patient. This observation could be explained by maternal imprinting. We found evidence supporting this hypothesis in a database of imprinted genes. In addition, our results generated new candidate genes for the mental retardation, dysmorphic facies, small joints contractions, small teeth, and anisomastia of the patient. We used a high density oligonucleotide microarray to delineate the borders of the duplication with high resolution. This analysis enabled us to confirm the inclusion of FTO in the duplication. This was confirmed with quantitative real-time PCR (qPCR) at the level of genomic DNA. To further investigate the role of FTO in the obese phenotype of the patient, we used qPCR to study the expression of FTO in immortalized lymphocytes of the patient. Remarkably, the increased FTO copy number in the patient’s genomic DNA did not give rise to an increased copy number of FTO mRNA molecules. We think this may be the result of maternal imprinting of the gene. The CGH results also allowed us to generate new hypotheses regarding the etiology of the other clinical problems of the patient. We propose candidate genes for her mental retardation, dysmorphic facies, joint contractures, small teeth, and anisomastia.

Project description:BACKGROUND:Parental balanced reciprocal translocations can result in partial aneuploidies in the offspring due to unbalanced meiotic segregation during gametogenesis. Herein, we report the phenotypic and molecular cytogenetic characterization of a 2 years and 4 months old female child with partial trisomy 7q22???qter. This is the first such reported case resulting from a parental balanced translocation involving the long arms of chromosomes 7 and 14. The phenotype of the proband was compared with that of previously reported cases of trisomy 7q21???qter or 7q22???qter resulting from parental balanced translocations. CASE PRESENTATION:The proband was born pre-term to a 34-year-old mother with a history of two first trimester miscarriages and an early infant death. She was referred at the age of 8 months for genetic evaluation due to prenatal and postnatal growth retardation, developmental delay and multiple congenital anomalies. On clinical evaluation, she had craniofacial dysmorphic features such as scaphocephaly, large anterior fontanelle with open posterior fontanelle, prominent occiput, triangular face, high forehead, hypertelorism, down slanting eyes, flat nasal bridge, small nose, low set ears, micro-retrognathia, high arched palate and short neck. Cranial computerized tomography scan showed lateral ventriculomegaly with features of early cerebral atrophy. Conventional cytogenetic analysis showed the karyotype 46,XX,der(14)t(7;14)(q22;q32)mat in the proband due to an unbalanced segregation of a maternal balanced translocation t(7;14)(q22;q32). Fluorescence in-situ hybridization analysis confirmed the partial trisomy 7q22???qter in the proband with a minimal loss of genetic material on chromosome 14. Single nucleotide polymorphism array further confirmed the duplication on chromosome 7q22.1???qter and a small terminal deletion on chromosome 14q32.3???qter. CONCLUSION:We report the longest-surviving child with trisomy 7q22???qter due to a parental balanced translocation between chromosomes 7 and 14. Clinical features observed in the proband were consistent with the consensus phenotype of partial trisomy 7q22???qter reported in the scientific literature. Early diagnosis of these patients using molecular cytogenetic techniques is important for establishing the precise diagnosis and for making decisions pertaining to the prognostication and management of affected individuals.

Dataset Information

Partial trisomy 16q and partial monosomy 7p of a fetus derivated from paternal balanced translocation: A case report.

Introduction

Patient concern

Diagnoses

Interventions

Outcomes

Conclusions

Publications

Partial trisomy 16q and partial monosomy 7p of a fetus derivated from paternal balanced translocation: A case report.

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