Prenatal diagnosis and molecular cytogenetic analysis of partial monosomy 10q (10q25.3→qter) and partial trisomy 18q (18q23→qter) in a fetus associated with cystic hygroma and ambiguous genitalia

Current Perspectives of Prenatal Cell-free DNA Screening in Clinical Management of First-Trimester Septated Cystic Hygroma

First-trimester septated cystic hygroma occurs in approximately 1 in 268 pregnancies and has long been associated with a markedly increased risk of fetal aneuploidy and, among euploid fetuses, an increased risk of structural anomalies primarily affecting the cardiac and skeletal systems. Invasive prenatal diagnosis – chorionic villus sampling and/or amniocentesis – encompasses the time-honored clinical tools for the next step in management following prenatal sonographic diagnosis of first-trimester septated cystic hygroma. Currently, prenatal cell-free DNA (cfDNA) screening for fetal aneuploidy with select microdeletions is gradually replacing the considerably less sensitive, and labor-intensive combined first-trimester screening. These new technologies have opened potential new venues in the clinical management of this ominous late first-trimester sonographic diagnosis. Advances in cfDNA technologies are now permitting detection of chromosomal copy number variants (CNV) larger than 7Mb across genome and select serious single-gene disorders (mainly impacting skeletal and neurological development), affecting quality of life and may benefit from medical and/or surgical management. This commentary will address the available non-invasive prenatal screening technologies, which clearly enhance immediate genetic analysis modalities applicable in the presence of the complex sonographic finding of first-trimester septated cystic hygroma.

Prenatal diagnosis of concomitant distal 5q duplication and terminal 10q deletion in a fetus with intrauterine growth restriction, congenital diaphragmatic hernia and congenital heart defects

OBJECTIVE

We present prenatal diagnosis of concomitant distal 5q duplication and terminal 10q deletion in a fetus with intrauterine growth restriction (IUGR), congenital diaphragmatic hernia (CDH) and congenital heart defects (CHD).

CASE REPORT

A 34-year-old, gravida 4, para 2, woman was referred for amniocentesis at 21 weeks of gestation because of advanced maternal age and IUGR. There was no congenital malformation in the family. Amniocentesis revealed a derivative chromosome 10 with an additional maternal on the terminal region of 10q. Array comparative genomic hybridization (aCGH) analysis on the DNA extracted from the cultured amniocytes revealed a result of arr 5q31.3q35.5 (142, 548, 354-180,696,806) × 3.0, arr 10q26.3 (132, 932, 808-135,434,178) × 1.0 [GRCh37 (hg19)] with a 2.50-Mb deletion of 10q26.3 encompassing 19 [Online Mendelian Inheritance in Man (OMIM)] genes and a 38.15-Mb duplication of 5q31.3-q35.5 encompassing 195 OMIM genes including four CDH candidate genes of NDST1, ADAM19, NSD1 and MAML1. The mother was found to have a karyotype of 46,XX,t(5; 10) (q31.3; q26.3). Therefore, the fetal karyotype was 46,XX,der(10)t(5; 10)(q31.3; q26.3)mat. Prenatal ultrasound showed IUGR, right CDH, transposition of great artery, double outlet of right ventricle and right atrial isomerism. The pregnancy was terminated, and a malformed fetus was delivered with facial dysmorphism.

CONCLUSION

Fetuses with concomitant distal 5q duplication and terminal 10q deletion may present IUGR, CDH and CHD on prenatal ultrasound.

Phenotype to genotype characterization by array-comparative genomic hydridization (a-CGH) in case of fetal malformations: A systematic review

The aim of the current review is to report a-CGH abnormalities identified in fetuses with prenatally diagnosed fetal malformations in whom a normal karyotype was diagnosed with conventional cytogenetic analysis. A systematic electronic search of databases (PubMed/Medline, EMBASE/SCOPUS) has been conducted from inception to May, 2017. Bibliographic analysis has been performed according to PRISMA statement for review. The following keywords were used: 'array-CGH' and 'fetal malformations" and "prenatal diagnosis"; alternatively, "microarray", "oligonucleotide array", "molecular biology", "antenatal diagnostics", "fetal diagnostics", "congenital malformations" and "ultrasound" were used to capture both "a-CGH" and "prenatal". One-hundred and twelve fetuses with prenatally diagnosed fetal malformations with normal karyotyping and a-CGH abnormalities detected are described. Single or multiple microarray abnormalities diagnosed have been classified in relation to different organ/system affected. The most frequent a-CGH abnormalities were detected in cases of congenital heart diseases (CDHs), multiple malformations and central nervous system (CNS) malformations. Maternal or paternal carrier-state was seen in 19.64% (22/112), of cases while the number of reported de novo mutations accounted for 46.42% (52/112) of all CNVs microarray abnormalities. Array-comparative genomic hydridization (a-CGH) may become an integral and complemantary genetic testing when fetal malformations are detected prenatally in fetuses with normal cytogenetic karyotype. In addition, a-CGH enables the identification of CNVs and VOUS and improves the calculation of recurrent risk and the genetic counseling.

Persistence of müllerian duct structures in a genetic male with distal monosomy 10q

Persistent müllerian duct syndrome (PMD) with antimüllerian hormone (AMH) deficiency is usually associated with mutations or deletions of the AMH gene, although many cases have no identified gene association. We report on a genetic male with PMD and AMH deficiency associated with distal monosomy 10q. A term 3,230 g infant was born to a healthy 27-year-old. Fetal ultrasound had shown possible genital ambiguity. Postnatal exam showed a 0.5 cm phallus with basal meatus, normal scrotum with no palpable gonads, no vaginal orifice, and a rectal fistula with an imperforate anus. Voiding cystourethrogram with ultrasound, cystoscopy, and laparoscopy showed normal bladder, urethral orifice, distal vagina, cervix, and bilateral abdominal testis. At 24 hours of life, testosterone was within normal range with low AMH level. Chromosome microarray analysis showed 46, XY, del10(10q25.3q26.13) involving an 8.2 MB interstitial deletion. Whole exome sequencing identified a NOTCH2 variant (1p11.2). AMH sequencing revealed no abnormalities. Following multidisciplinary team and parent discussion, male gender was assigned. Testosterone treatment resulted in penile length of 1.5 cm. Bilateral orchiopexy and posterior sagittal anorectoplasty were performed at 11 months of age; rudimentary müllerian structures were identified. This observation suggests an association of 10qter elements with male differentiation including AMH expression and is similar to a patient with 46, XY, del(10q26.1) in which AMH levels were not reported. Regional candidate genes include FGFR2 (10q26.13). The possible contribution of a NOTCH2 variant cannot be excluded.

When Cri du chat syndrome meets Edwards syndrome

It has been well established that the 5p deletion causes Cri du chat syndrome, typically characterized by a cat‑like cry, and that duplication of 18q causes Edwards syndrome; the two are rare genetic abnormalities that separately lead to physical and mental impairments. However, the severity of the clinicopathological characteristics that arise when these two aberrations occur in one patient is unknown. Here, the first case in our knowledge of a single patient (a two‑year‑old female) with 5p partial monosomy and 18q partial trisomy is described. In the present study, chromosome microarray analysis was performed, which identified the imbalance of chromosomes 5 and 18 in the patient. The chromosome aberrations were further confirmed by fluorescence in situ hybridization. By comparing the phenotypes of combined case with those of the individual syndromes, severe clinical phenotypes of the 5p (5p15.33‑p13.3) deletion were confirmed, however, the net effect of the duplication of 18q22.3‑q23 was not determined, as this duplication only appeared to have a weak effect on the patient's phenotypes. The correlation between these chromosomal aberrations and their clinical features has implications for the identification of critical regions of 5p and 18q, particularly for the functional mapping of chromosome 18.

Rapid aneuploidy diagnosis of partial trisomy 7q (7q34→qter) and partial monosomy 10q (10q26.12→qter) by array comparative genomic hybridization using uncultured amniocytes

OBJECTIVE

To present rapid aneuploidy diagnosis (RAD) of partial trisomy 7q (7q34→qter) and partial monosomy 10q (10q26.12→qter) by array comparative genomic hybridization (aCGH) using uncultured amniocytes.

CASE REPORT

A 34-year-old, gravida 2, para 1, woman underwent amniocentesis at 20 weeks of gestation because of a previous mentally retarded child with an unbalanced reciprocal translocation inherited from the carrier father who had a karyotype of 46,XY,t(7;10) (q34;q26.12). Her first child was initially found to have a normal karyotype by routine cytogenetic analysis, but a cryptic chromosomal abnormality was subsequently diagnosed by aCGH. During this pregnancy, RAD by oligonucleotide-based aCGH using uncultured amniocytes revealed a 16.4-Mb duplication of 7q34-q36.3 and a 12.7-Mb deletion of 10q26.12-q26.3. Conventional cytogenetic analysis using cultured amniocytes revealed a karyotype of 46,XX,der(10)t(7;10)(q34;q26.12)pat. The parents elected to terminate the pregnancy. A malformed female fetus was delivered with a high prominent forehead, hypertelorism, epicanthic folds, a broad depressed nasal bridge, a prominent nose with anteverted nostrils, micrognathia, a short neck, large low-set ears, clinodactyly, small big toes, and normal female external genitalia.

CONCLUSION

aCGH is a useful tool for RAD of subtle chromosomal rearrangements in pregnancy, especially under the circumstance of a previous abnormal child with an unbalanced translocation derived from a parental subtle reciprocal translocation.

Genome-wide detection of uniparental disomy in a fetus with intrauterine growth restriction using genotyping microarrays

OBJECTIVE

To present the clinical and molecular features of a fetus with confined trisomy 16 mosaicism with maternal uniparental disomy (UPD), using various prenatal diagnostic techniques.

MATERIALS AND METHODS

Chromosomal karyotyping was performed on samples of chorionic villi, amniotic fluid cells, amniotic membrane, umbilical cord, fetal skin, and placenta from a fetus with elevated nuchal translucency. Polymorphic short tandem repeat markers and Affymetrix single nucleotide polymorphism (SNP) mapping chips were used for molecular analyses.

RESULTS

Karyotypes from chorionic villi and amniocytes showed 47,XX,+16 and 46,XX, respectively. Short tandem repeat markers on chromosome 16 suggested maternal UPD for chromosome 16. Affymetrix 10K SNP mapping chips were used to simultaneously confirm the difference in karyotypes between the placenta and amniocytes and to diagnose UPD for chromosome 16. Fetal ultrasonography and magnetic resonance imaging identified severe intrauterine growth restriction (IUGR). Autopsy revealed IUGR, incomplete lobulation of bilateral lungs, and malrotation of the intestines. The karyotypes of umbilical cord, fetal skin and amniotic membrane were 46,XX, and the trisomy 16 karyotype appeared to be confined to the placenta.

CONCLUSION

UPD should be investigated as a possible etiology in all cases of unexplained IUGR. SNP microarrays can be useful for confirming this diagnosis.

Identification of critical regions for clinical features of distal 10q deletion syndrome

Array comparative genomic hybridization studies were performed to further characterize cytogenetic abnormalities found originally by karyotype and fluorescence in situ hybridization in five clinical cases of distal 10q deletions, including several with complex cytogenetic rearrangements and one with a partial male-to-female sex-reversal phenotype. These results have enabled us to narrow the previously proposed critical regions for the craniofacial, urogenital, and neuropsychiatric disease-related manifestations associated with distal 10q deletion syndrome. Furthermore, we propose that haploinsufficiency of the DOCK1 gene may play a crucial role in the pathogenesis of the 10q deletion syndrome. We hypothesize that alteration of DOCK1 and/or other genes involved in regulation and signaling of multiple pathways can explain the wide range of phenotypic variability between patients with similar or identical cytogenetic abnormalities.

Molecular (SNP) analyses of overlapping hemizygous deletions of 10q25.3 to 10qter in four patients: evidence for HMX2 and HMX3 as candidate genes in hearing and vestibular function

We report on the analyses of four unrelated patients with de novo, overlapping, hemizygous deletions of the long arm of chromosome 10. These include two small terminal deletions (10q26.2 to 10qter), a larger terminal deletion (10q26.12 to 10qter), and an interstitial deletion (10q25.3q26.13). Single nucleotide polymorphism (SNP) studies (Illumina 550 K) established that these deletions resulted in the hemizygous loss of approximately 6.1, approximately 6.1, approximately 12.5, and approximately 7.0 Mb respectively. Additionally, these data establish that Patients 1, 2, and 3 share common, distal, hemizygous deleted regions of 6.09 Mb containing 37 RefSeq genes. Patients 3 and 4 share a 2.52 Mb deleted region corresponding to the proximal deleted region of Patient 3 and the distal deleted region of Patient 4. This common, hemizygous region contains 20 RefSeq genes including two H6 family homeobox genes (HMX2 and HMX3). Based on previous reports that Hmx2/Hmx3 knockout mice have vestibular anomalies, we propose that hemizygous deletions of HMX2 and HMX3 are responsible for the inner ear malformations observed from CT images, vestibular dysfunction, and congenital sensorineural hearing loss found in Patients 3 and 4.

Prenatal genomic profiling of abdominal wall defects through comparative genomic hybridization: perspectives for a new diagnostic tool

OBJECTIVES

To describe the molecular analysis through comparative genomic hybridization (CGH) of fetuses with gastroschisis, and to observe if this technique could improve the resolution of the conventional cytogenetic techniques.

METHODS

Amniotic analysis of fetuses with gastroschisis, using both conventional (G-banding) and molecular (CGH) cytogenetics assays.

RESULTS

All of the seven fetuses studied displayed a normal G-band karyotype. Six fetuses displayed a normal disomic profile through CGH and one sample has displayed ish cgh enh 3q26-->qter result (ICSN). The fetus with this imbalance of chromosome 3 was re-classified as a ruptured omphalocele, instead of gastroschisis, after birth.

CONCLUSIONS

The molecular investigation through CGH technique can improve the resolution of the conventional karyotye analysis in cases of abdominal wall defects.

Microarray-based comparative genomic hybridization analysis of Wolf-Hirschhorn syndrome in a fetus with deletion of 4p15.3 to 4pter

BACKGROUND

Wolf-Hirschhorn syndrome (WHS), caused by the deletion of a segment in chromosome 4, is characterized by mental and developmental defects. Clinical manifestations of WHS include intrauterine growth restriction, failure to thrive in the neonatal period that is present simultaneously with hypotonia, typical "Greek helmet" facial appearance, cleft lip and palate, mental deficiency, and seizures.

CASE

We present a case of WHS with prenatal conventional cytogenetics of 46,XY,der(4)t(4;13)(p15.3;p11.2)pat. High-resolution mapping using microarray-based comparative genomic hybridization (array-CGH), including Affymetrix 10K arrays and cDNA microarrays, confirmed the loss of genes in the deleted region.

CONCLUSIONS

The correlation between these candidate genes and the phenotypes of WHS may expand our understanding of the defective development caused by 4p deletion.