Prenatal diagnosis of complete trisomy 19q

Confined placental mosaicism and the association with pregnancy outcome and fetal growth: a review of the literature

BACKGROUND

Chromosomal mosaicism can be detected in different stages of early life: in cleavage stage embryos, in blastocysts and biopsied cells from blastocysts during preimplantation genetic testing for aneuploidies (PGT-A) and later during prenatal testing, as well as after birth in cord blood. Mosaicism at all different stages can be associated with adverse pregnancy outcomes. There is an onward discussion about whether blastocysts diagnosed as chromosomally mosaic by PGT-A should be considered safe for transfer. An accurate diagnosis of mosaicism remains technically challenging and the fate of abnormal cells within an embryo remains largely unknown. However, if aneuploid cells persist in the extraembryonic tissues, they can give rise to confined placental mosaicism (CPM). Non-invasive prenatal testing (NIPT) uses cell-free (cf) DNA released from the placenta in maternal blood, facilitating the detection of CPM. In literature, conflicting evidence is found about whether CPM is associated with fetal growth restriction (FGR) and/or other pregnancy outcomes. This makes counselling for patients by clinicians challenging and more knowledge is needed for clinical decision and policy making.

OBJECTIVE AND RATIONALE

The objective of this review is to evaluate the association between CPM and prenatal growth and adverse pregnancy outcomes. All relevant literature has been reviewed in order to achieve an overview on merged results exploring the relation between CPM and FGR and other adverse pregnancy outcomes.

SEARCH METHODS

The following Medical Subject Headings (MESH) terms and all their synonyms were used: placental, trophoblast, cytotrophoblast, mosaicism, trisomy, fetal growth, birth weight, small for gestational age and fetal development. A search in Embase, PubMed, Medline Ovid, Web of Science, Cochrane Central Register of Controlled Trials (CENTRAL) and Google Scholar databases was conducted. Relevant articles published until 16 July 2020 were critically analyzed and discussed.

OUTCOMES

There were 823 articles found and screened based on their title/abstract. From these, 213 articles were selected and full text versions were obtained for a second selection, after which 70 publications were included and 328 cases (fetuses) were analyzed. For CPM in eight different chromosomes (of the total 14 analyzed), there was sufficient evidence that birth weight was often below the 5th percentile of fetal growth standards. FGR was reported in 71.7% of CPM cases and preterm birth (<37 weeks of delivery) was reported in 31.0% of cases. A high rate of structural fetal anomalies, 24.2%, in cases with CPM was also identified. High levels of mosaicism in CVS and presence of uniparental disomy (UPD) were significantly associated with adverse pregnancy outcomes.

WIDER IMPLICATIONS

Based on the literature, the advice to clinicians is to monitor fetal growth intensively from first trimester onwards in case of CPM, especially when chromosome 2, 3, 7, 13, 15, 16 and 22 are involved. In addition to this, it is advised to examine the fetuses thoroughly for structural fetal anomalies and raise awareness of a higher chance of (possibly extreme) premature birth. Despite prematurity in nearly a fifth of cases, the long-term follow-up of CPM life borns seems to be positive. More understanding of the biological mechanisms behind CPM will help in prioritizing embryos for transfer after the detection of mosaicism in embryos through PGT-A.

Prenatal detection and molecular cytogenetic characterization of 19q13.42 microduplication: three reported cases and literature review

Background

Trisomy 19q is a recognizable syndrome and associated with a wide spectrum of clinical phenotypes in clinic. The purpose of this study was to explore the prenatal phenotypes of 19q13.42 duplication, which was rarely reported in clinic.

Case presentation

Three pregnant women presenting diverse indications for prenatal diagnosis accepted amniocentesis: increased nuchal translucency and fetal pyelic separation (case 2) and high risk of maternal serum screening for Down syndrome (case 1 and case 3). Case 1 and case 2 shared similar duplicated locus in the region of 19q13.42, encompassing part NLRP12 gene. The latter inherited the chromosomal duplication from the mother with normal phenotypes. Case 3 carried a 1.445 Mb duplication in the 19q13.42q13.43 region. It was proposed that evolutionary duplication of NLRP12 gene could have a causative role in autoinflammatory diseases development. The genotype–phenotype correlation depends mainly on the duplicated size and functional genes involved, which is still yet to be determined. All pregnant women chose to continue the pregnancy and delivered healthy children with no apparent abnormalities.

Conclusions

The 19q13.42 microduplications in our study were the smallest fragments compared to previous literature. Our findings enriched the prenatal phenotypes for this chromosomal microscopic imbalance. It was proposed that long term follow up analysis should be guaranteed till adulthood to determine whether there will be other emerging clinical symptoms and developmental-behavioral disorders for such carriers.

A Novel 1.13 Mb Interstitial Duplication at 19q13.32 Causing Developmental Delay and Microcephaly in a Pediatric Patient: the First Asian Case Reports

Only 6 patients with partial trisomy of the long arm of chromosome 19 (19q), caused by direct interstitial duplications, have been reported until today. Herein, we report a pediatric patient with a novel 1.13 Mb direct interstitial duplication within 19q13.32, which is the smallest fragment affected so far. A five-year old Korean boy of healthy parents presented with microcephaly, growth retardation, developmental delay, and craniofacial dysmorphism. Even though G-banded chromosome analysis at resolution of 550-band revealed normal karyotype, duplication of 1.13 Mb fragment within 19q13.32 was detected by array comparative genomic hybridization. Comparing with previously reported patients with pure duplication involving 19q as a sole chromosomal abnormality, our case showed the smallest duplication segment with relatively mild degree of clinical features. Our present case might serve as the landmark case among patients with 19q duplication for genotype-phenotype correlation study and further identification of critical region for 19q duplication abnormalities.

19q13.33→qter trisomy in a girl with intellectual impairment and seizures

Rearrangements in chromosome 19 are rare. Among the 35 patients with partial 19q trisomy described, only six have a breakpoint defined by array. The 19q duplication results in a variable phenotype, including dysmorphisms, intellectual disability and seizure. In a female patient, although G-banding at 550 band-resolution was normal, multiplex ligation-dependent probe amplification (MLPA) technique and genomic array showed a 10.6 Mb terminal duplication of chromosome 19q13. Fluorescent in situ hybridization (FISH) revealed that the duplicated region was attached to the short arm of chromosome 21 and silver staining showed four small acrocentrics with nucleolar organization region (NOR) activity, suggesting that the breakpoint in chromosome 21 was at p13. This is the first de novo translocation between 19q13.33 and 21p13 described in liveborn. The chromosome 19 is known to be rich in coding and non-coding regions, and chromosomal rearrangements involving this chromosome are very harmful. Furthermore, the 19q13.33→qter region is dense in pseudogenes and microRNAs, which are potent regulators of gene expression. The trisomic level of this region may contribute to deregulation of global gene expression, and consequently, may lead to abnormal development on the carriers of these rearrangements.

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The first patient with a de novo translocation between 19q13.33 and 21p13 reported in liveborn.

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The patient clinical and cytogenetic analyses are reported in details.

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Rearrangements in 19q13.33→qter region are correlated to intellectual disability and seizures.

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Chromosomal rearrangements involving rich coding and non-coding regions appear to be very harmful.

dup(19)(q12q13.2): array-based genotype-phenotype correlation of a new possibly obesity-related syndrome

Small supernumerary marker chromosomes (sSMCs) derived from the near-centromeric area of chromosome 2 are very rare. In addition, duplications of the 2p11.2-->q11.2 region have displayed considerable variability between patients harboring and lacking clinical findings. Moreover, constitutional duplication of the 19q12-->q13.2 region has previously only been described in two cases and was associated with delay of developmental milestones, corpus callosum anomalies, and obesity. Herein, we present a genotype-phenotype correlation in a patient harboring two sSMCs derived from chromosomes 2 and 14 or 22, respectively. The DNA was studied using G-banding, fluorescence in situ hybridization techniques, and array-based comparative genomic hybridization. A 48,XX,+der(2)del(2)(p11)del(2)(q11.2),+der(14)t(14;19)(q11;q12)del(19)(q13.31) or 48,XX,+der(2)del(2)(p11)del(2)(q11.2),+der(22)t(22;19)(q11;q12)del(19)(q13.31) was detected in the patient. The sSMC 14;19 or 22;19, with its centromere originating from either chromosome 14 or 22, encompassed a 13.56 megabase (Mb) 19q derived region, harboring 263 genes, and the sSMC 2 a 2.71 Mb region including 29 genes. The patient had symptoms including a ventral septal defect, bilateral grade IV urinary reflux, corpus callosum agenesis, microphthalmia, and obesity. The 19q segment contained the genes AKT2, CEACAM1, CEBPA, LIPE, and TGFB1 which are involved in adipose tissue homeostasis and insulin resistance, and could potentially contribute to the obese phenotype observed. Array-based genetic characterization and long-term clinical evaluation with attention toward weight gain in patients with chromosome 19q duplications might in the future lead to the description of a obesity-associated genetic syndrome, something that could have implications in management and treatment of patients carrying a dup(19)(q12q13.2). Whether the der(2)(p11q11.2) contributes to the phenotype remains inconclusive.

Two cases of trisomy 19 as a sole chromosomal abnormality in myeloid disorders

Trisomy 19 is frequently encountered in cases of chronic myeloid leukemia (CML) as a secondary abnormality: however, trisomy 19 rarely occurs as a sole chromosomal abnormality and, to date, it has only been reported in 48 hematopoietic malignancies, 1 case of adenocarcinoma and 1 case of astrocytic tumor. Here, we report two additional cases of trisomy 19 as a sole karyotypic aberration in myeloid malignancies. One of these cases involved a 6-month-old male who was diagnosed with acute myeloid leukemia minimally differentiated. His karyotype was 47,XY,+19[20]. He expired 5 days after diagnosis. Another case occurred in an 80-yr-old female who had refractory anemia with excess blasts. Her karyotype was 47,XX,+19[16]/46,XX[4]. Four months later, her peripheral blood smears suggested that the disease had progressed, but she refused further evaluation. Based on a review of the existing literature and the results of this report, trisomy 19 not only as a secondary abnormality but also as a sole karyotypic aberration is strongly associated with myeloid disorder; however, it is not preferentially found in specific FAB subgroups of myelodysplasic syndrome or acute myeloid leukemia.