A severe neurocognitive phenotype caused by biallelic CHD3 variants in two siblings

CHD3 heterozygous variants are associated with Snijders Blok-Campeau syndrome (SBCS) which consists of intellectual disability (ID), macrocephaly, and dysmorphic facies. Most reported variants are missense or loss of function clustered within the ATPase/helicase domain of the protein. We report a severe neurocognitive phenotype caused by biallelic CHD3 variants in two siblings, each inherited from a mildly affected parent. Male and female siblings were referred to the Genetics Clinic due to severe ID and profound dysmorphism. The parents are first cousins of Iranian descent with borderline intellectual abilities. Exome sequencing was performed for the affected female and her parents. A single homozygous candidate variant in the CHD3 gene was detected in the proband: c.5384_5389dup. p.Arg1796_Phe1797insTrpArg, resulting in an in-frame insertion of 2 amino acids located outside the ATPase/helicase domain at the C-terminal region of CHD3-encoding residues. This variant is classified as likely pathogenic according to ACMG guidelines. The variant was detected in a heterozygous state in each parent. Both affected siblings were homozygous, while their unaffected brother did not carry the variant. Biallelic CHD3 variants cause a severe neurodevelopmental syndrome that is distinguishable from SBCS. We assume that the variant type (in-frame insertion) and location may enable CHD3 biallelic variants.

The Yield of Chromosomal Microarray in Pregnancies Complicated with Fetal Growth Restriction Can Be Predicted According to Clinical Parameters

INTRODUCTION

We evaluated the yield of chromosomal microarray analysis in pregnancies complicated with fetal growth restriction (FGR) according to specific clinical parameters.

METHODS

The study was based on national records from the Israeli Ministry of Health. Chromosomal microarray analyses of amniocenteses performed nationwide for the indication of FGR, from January 2016 to March 2018, were included. The CMA yield was compared to 2 cohorts that reported the background risk.

RESULTS

Of 174 tests performed for the indication of FGR, there were 11 cases with a pathogenic/likely pathogenic result (6.3%). The yield of CMA was significantly higher in cases with major structural findings (29.4 vs. 3.4%, p = 0.001), compared to isolated FGR but not for minor structural findings (6.1 vs. 3.4%, p = 0.5). The rate of chromosomal aberrations was significantly higher for all cases with FGR, when compared to the background risk of a cohort of normal pregnancies (odds ratio [OR] 4.7, 95% CI 2.5-9 and OR 6.09, 95% CI 3.2-11.4) but not for isolated cases or cases diagnosed after 24 weeks of pregnancy.

CONCLUSIONS

Chromosomal microarray analysis should be performed for all pregnancies complicated with FGR diagnosed before 24 weeks and for cases with major structural anomalies.

The yield of chromosomal microarray testing for cases of abnormal fetal head circumference

OBJECTIVES

Chromosomal microarray analysis (CMA) is the method of choice for genetic work-up in cases of fetal malformations. We assessed the detection rate of CMA in cases of abnormal fetal head circumference (HC).

METHODS

The study cohort was based on 81 cases of amniocenteses performed throughout Israel for the indication of microcephaly (53) or macrocephaly (28), from January 2015 through December 2018. We retrieved data regarding the clinical background, parental HCs and work-up during the pregnancy from genetic counseling summaries and from patients' medical records.

RESULTS

There was only one likely pathogenic CMA result (1.89%): a 400-kb microdeletion at 16p13.3 detected in a case of isolated microcephaly. No pathogenic results were found in the macrocephaly group. Most fetuses with microcephaly were female (87.8%), while the majority with macrocephaly were males (86.4%).

CONCLUSIONS

The results imply that CMA analysis in pregnancies with microcephaly may carry a small yield compared to other indications. Regarding macrocephaly, our cohort was too small to draw conclusions. In light of the significant gender effect on the diagnosis of abnormal HC, standardization of fetal HC charts according to fetal gender may normalize cases that were categorized outside the normal range and may increase the yield of CMA for cases of abnormal HC.

Bi-allelic ADARB1 Variants Associated with Microcephaly, Intellectual Disability, and Seizures

The RNA editing enzyme ADAR2 is essential for the recoding of brain transcripts. Impaired ADAR2 editing leads to early-onset epilepsy and premature death in a mouse model. Here, we report bi-allelic variants in ADARB1, the gene encoding ADAR2, in four unrelated individuals with microcephaly, intellectual disability, and epilepsy. In one individual, a homozygous variant in one of the double-stranded RNA-binding domains (dsRBDs) was identified. In the others, variants were situated in or around the deaminase domain. To evaluate the effects of these variants on ADAR2 enzymatic activity, we performed in vitro assays with recombinant proteins in HEK293T cells and ex vivo assays with fibroblasts derived from one of the individuals. We demonstrate that these ADAR2 variants lead to reduced editing activity on a known ADAR2 substrate. We also demonstrate that one variant leads to changes in splicing of ADARB1 transcript isoforms. These findings reinforce the importance of RNA editing in brain development and introduce ADARB1 as a genetic etiology in individuals with intellectual disability, microcephaly, and epilepsy.

Characterization of functional transposable element enhancers in acute myeloid leukemia

Transposable elements (TEs) have been shown to have important gene regulatory functions and their alteration could lead to disease phenotypes. Acute myeloid leukemia (AML) develops as a consequence of a series of genetic changes in hematopoietic precursor cells, including mutations in epigenetic factors. Here, we set out to study the gene regulatory role of TEs in AML. We first explored the epigenetic landscape of TEs in AML patients using ATAC-seq data. We show that a large number of TEs in general, and more specifically mammalian-wide interspersed repeats (MIRs), are more enriched in AML cells than in normal blood cells. We obtained a similar finding when analyzing histone modification data in AML patients. Gene Ontology enrichment analysis showed that genes near MIRs in open chromatin regions are involved in leukemogenesis. To functionally validate their regulatory role, we selected 19 MIR regions in AML cells, and tested them for enhancer activity in an AML cell line (Kasumi-1) and a chronic myeloid leukemia (CML) cell line (K562); the results revealed several MIRs to be functional enhancers. Taken together, our results suggest that TEs are potentially involved in myeloid leukemogenesis and highlight these sequences as potential candidates harboring AML-associated variation.

The yield of chromosomal microarray analysis among pregnancies terminated due to fetal malformations

Background: Chromosomal microarray analysis (CMA) is preferred for genetic work-up when fetal malformations are detected prenatally.Objectives: To assess the detection rate of CMA after pregnancy termination due to abnormal ultrasound findings.Methods: CMA was successfully performed in 71 pregnancies using fetal DNA (mainly from skin) or placenta. Data regarding clinical background, pregnancy work-up, and CMA were analyzed.Results: Findings were abnormal in 17 cases (23.9%), of which 13 were detectable by karyotype. The incremental yield of CMA was 4/71 (5.6%); 1/32 (3.1%) for cases with an isolated anomaly and 3/39 (7.7%) for cases with nonisolated anomalies.Conclusions: CMA yield from terminated pregnancies was 23.9%. Although most chromosomal abnormalities are detectable by karyotype, CMA does not require viable dividing cells; hence, it is more practical for work-up after termination. In most cases, the diagnosis was followed by consultation regarding the risk of recurrence and recommendations for testing in subsequent pregnancies.

A Rare Case of 7 Simultaneous Arterial Dissections and Review of The Literature

Objective:

Spontaneous multiple artery dissection is a relatively rare phenomenon. Early clinical signs are often nonspecific, making it difficult to diagnose.

Case Report:

This is a case of a 51-year-old female who presented with spontaneous dissection of 4 visceral arteries, both iliac arteries, and of the right internal carotid artery. The patient underwent urgent successful endovascular repair. Later complications included acute respiratory distress syndrome and pneumonia after massive blood transfusion. She recovered gradually and was discharged after 21 days. Due to this rare presentation, genetic investigation was performed in search of a connective tissue disorder. Results revealed a new COL3A1 subtype mutation. The pathogenicity of this variant remains unclear.

Conclusion:

We recommend a high index of suspicion for visceral artery dissection in the differential diagnosis for abdominal pain with concurrent uncontrolled hypertension. Early diagnosis and intervention are crucial to reducing the mortality rate.

Mutations in the fourth β-propeller domain of LRP4 are associated with isolated syndactyly with fusion of the third and fourth fingers

Isolated hand syndactyly is a common limb malformation with limited known genetic etiology. We used exome sequencing to discover two novel variants, chr11 g.46896373C>G; p.D1403H and chr11 g.46893078G>T; p.Q1564K, in LRP4 in a child with isolated bilateral syndactyly of the third and fourth fingers. Each variant was inherited from a different parent and neither parent was affected. Variants in LRP4 have been previously associated with syndactyly in Cenani-Lenz syndactyly syndrome and Sclerosteosis 2, but have not been reported in individuals with isolated syndactyly. LRP4 inhibits LRP6/LRP5-mediated activation of canonical Wnt signaling and mediates sclerostin-dependent inhibition of bone formation. p.D1403H and p.Q1564K are located within the fourth β-propeller of the extracellular protein domain that has yet to be associated with human disease. Functional analyses of p.D1403H and p.Q1564K show that they significantly decrease LRP4's inhibition of Wnt signaling. These results suggest that variants in the fourth β-propeller of the extracellular protein domain may cause a phenotype distinct from previously characterized LRP4 variants.

Telomeres are shorter in placental trophoblasts of pregnancies complicated with intrauterine growth restriction (IUGR)

OBJECTIVE

Telomeres are nucleoprotein structures located at the termini of chromosomes, and protect them from fusion and degradation. Telomeres are progressively shortened with each mitotic cycle and by environmental factors. We hypothesized that antepartum stress can lead to accelerated telomere shortening in placental trophoblasts, and plays a role in intrauterine growth restriction (IUGR).

METHODS

Placental biopsies were derived from 16 pregnancies complicated with IUGR and from 13 uncomplicated pregnancies. Fluorescence-in-situ protocol was used to determine telomere length. Immunohistochemistry for hTERT was performed to assess telomerase activity. Clinical and histopathological characteristics were collected to ensure that IUGR was secondary to placental insufficiency. Fluorescence-in-situ-hybridization was used to rule out aneuploidy as a reason for shortened telomeres.

RESULTS

The number and intensity of telomeres staining and telomerase activity were significantly lower in the IUGR placentas. No aneuploidy was detected for the chromosomes checked in the placental biopsies.

CONCLUSIONS

Telomeres are shorter in trophoblasts of IUGR placentas.

Contribution of sonographic measurement of ovarian volume to diagnosing ovarian tumors in postmenopausal women

The purpose of this review article is to evaluate the current method of sonographic measurement of ovarian volume as a means of diagnosing ovarian tumors in postmenopausal women, in whom an ovarian volume greater than 10 ml is generally considered abnormal. After reviewing the general medical literature, we propose a nomogram of ovarian volume that may be used to determine whether an ovary is abnormal. Furthermore, on the basis of our previous results, we recommend that a cutoff point for ovarian volume that is adjusted to patient age be used to determine whether an ovary is abnormal. We recommend the use of such nomograms in routine clinical practice to assist physicians in identifying abnormality of the ovaries during sonographic examination.