A mosaic intragenic microduplication of LAMA1 and a constitutional 18p11.32 microduplication in a patient with keratosis pilaris and intellectual disability

Prenatal diethylhexylphthalate exposure disturbs adult Leydig cell function via epigenetic downregulation of METTL4 expression in male rats

Prenatal exposure to diethylhexyl phthalate (DEHP) has been linked with a decline in testosterone levels in adult male rats, but the underlying mechanism remains unclear. We investigated the potential epigenetic regulation, particularly focusing on N6-methyladenosine (m6A) modification, as a possible mechanism. Dams were gavaged with DEHP (0, 10, 100, and 750 mg/kg/day) from gestational day 14 to day 21. The male offspring were examined at the age of 56 days. Prenatal DEHP administration at 750 mg/kg/day caused a decline in testosterone concentrations, an elevation in follicle-stimulating hormone, a downregulated expression of CYP11A1 HSD3B2, without affecting Leydig cell numbers. Interestingly, Methyltransferase Like 4 (METTL4), an m6A methyltransferase, was downregulated, while there were no changes in METTL3 and METTL14. Moreover, CYP11A1 showed m6A reduction in response to prenatal DEHP exposure. Additionally, METTL4 expression increased postnatally, peaking in adulthood. Knockdown of METTL4 resulted in the downregulation of CYP11A1 and HSD3B2 and an increase in SCARB1 expression. Furthermore, the increase in autophagy protection in adult Leydig cells induced by prenatal DEHP exposure was not affected by 3-methyladenosine (3MA) treatment, indicating a potential protective role of autophagy in response to DEHP exposure. In conclusion, prenatal DEHP exposure reduces testosterone by downregulating CYP11A1 and HSD3B2 via m6A epigenetic regulation and induction of autophagy protection in adult Leydig cells as a response to DEHP exposure.

Shared Neurodevelopmental Perturbations Can Lead to Intellectual Disability in Individuals with Distinct Rare Chromosome Duplications

Chromosomal duplications are associated with a large group of human diseases that arise mainly from dosage imbalance of genes within the rearrangements. Phenotypes range widely but are often associated with global development delay, intellectual disability, autism spectrum disorders, and multiple congenital abnormalities. How different contiguous genes from a duplicated genomic region interact and dynamically affect the expression of each other remains unclear in most cases. Here, we report a genomic comparative delineation of genes located in duplicated chromosomal regions 8q24.13q24.3, 18p11.32p11.21, and Xq22.3q27.2 in three patients followed up at our genetics service who has the intellectual disability (ID) as a common phenotype. We integrated several genomic data levels by identification of gene content within the duplications, protein-protein interactions, and functional analysis on specific tissues. We found functional relationships among genes from three different duplicated chromosomal regions, reflecting interactions of protein-coding genes and their involvement in common cellular subnetworks. Furthermore, the sharing of common significant biological processes associated with ID has been demonstrated between proteins from the different chromosomal regions. Finally, we elaborated a shared model of pathways directly or indirectly related to the central nervous system (CNS), which could perturb cognitive function and lead to ID in the three duplication conditions.

Projected supportive effects of PycnogenolⓇ in patients suffering from multi-dimensional health impairments after a SARS-CoV2 infection

Corona virus disease 2019 (COVID-19) is triggered by the Severe Acute Respiratory Syndrome Corona Virus 2 (SARS-CoV2) and has rapidly developed into a worldwide pandemic. Unlike other SARS viruses, SARS-CoV2 does not solely impact the respiratory system, but additionally leads to inflammation of endothelial cells, microvascular injuries and coagulopathies, thereby affecting multiple organs. Recent reports of patients who were infected with SARS-CoV2 suggest persistent health problems even months after the initial infection. The French maritime pine bark extract Pycnogenol^Ⓡ has demonstrated anti-inflammatory, vascular and endothelium-protective effects in over 90 human clinical studies. It is proposed that Pycnogenol^Ⓡ may be beneficial in supporting recovery and mitigating symptoms and long-term consequences resulting from a SARS-CoV2 infection in COVID-19 patients.

Bi-allelic Variants in METTL5 Cause Autosomal-Recessive Intellectual Disability and Microcephaly

Intellectual disability (ID) is a genetically and clinically heterogeneous disorder, characterized by limited cognitive abilities and impaired adaptive behaviors. In recent years, exome sequencing (ES) has been instrumental in deciphering the genetic etiology of ID. Here, through ES of a large cohort of individuals with ID, we identified two bi-allelic frameshift variants in METTL5, c.344_345delGA (p.Arg115Asnfs^∗19) and c.571_572delAA (p.Lys191Valfs^∗10), in families of Pakistani and Yemenite origin. Both of these variants were segregating with moderate to severe ID, microcephaly, and various facial dysmorphisms, in an autosomal-recessive fashion. METTL5 is a member of the methyltransferase-like protein family, which encompasses proteins with a seven-beta-strand methyltransferase domain. We found METTL5 expression in various substructures of rodent and human brains and METTL5 protein to be enriched in the nucleus and synapses of the hippocampal neurons. Functional studies of these truncating variants in transiently transfected orthologous cells and cultured hippocampal rat neurons revealed no effect on the localization of METTL5 but alter its level of expression. Our in silico analysis and 3D modeling simulation predict disruption of METTL5 function by both variants. Finally, mettl5 knockdown in zebrafish resulted in microcephaly, recapitulating the human phenotype. This study provides evidence that biallelic variants in METTL5 cause ID and microcephaly in humans and highlights the essential role of METTL5 in brain development and neuronal function.

Prenatal detection of interstitial 18p11.31-p11.22 microduplications: Phenotypic diversity and literature review

INTRODUCTION

Pure duplication of chromosome 18p is rare, with clinical phenotypes ranging from normal or slight abnormalities to various degrees of mental retardation. It remains difficult to establish a clear genotype-phenotype correlation.

METHODS

Chromosomal karyotyping analysis was performed on cultured amniotic fluid cells from three cases. Single nucleotide polymorphism (SNP) array analysis was carried out using the Illumina Human CytoSNP-12 BeadChip. We also carried out a review of the literature regarding 18p11 microduplication.

RESULTS

G-banding analysis showed that the three cases had normal karyotypes. SNP array results showed 0.48- to 1.6-Mb microduplications of 18p11.31-p11.22 (chr18: 6995739-8713088) in these cases, encompassing different degrees of LAMA1 duplication. Follow-up analysis showed that the parents of both cases 1 and 2 chose termination of pregnancy. Case 3 presented with normal growth and physical development. Currently, there is not enough evidence supporting the pathogenicity of LAMA1 triplosensitivity.

CONCLUSION

We described three prenatal cases with 18p11.31-p11.22 microduplications involving part of the LAMA1 locus. There might be phenotypic diversity associated with 18p11.31-p11.22 microduplications. To avoid unnecessary abortions for pregnancies such as these, comprehensive genetic counseling should be offered.

Detection of a rare de novo 18p terminal deletion with inverted duplication in a Chinese pregnant woman

Background

The 18p terminal deletion with inverted duplication is an extremely rare chromosome structure abnormality and the common clinical manifestations include intellectual disability and speech delay, etc. Up to now, only three confirmed cases were reported in Europe, and here, for the first time in the Asian population, we report a case of de novo 18p inv‐dup‐del in a Chinese pregnant woman. This structural variation was accidentally discovered by the noninvasive prenatal testing (NIPT) during her prenatal examination.

Methods

Next generation sequencing (NGS) based copy number variations (CNVs) screening and karyotype analysis were performed to verify the type and heredity of the rearrangement, and the fluorescent in situ hybridization (FISH) analysis was also used to confirm the terminal deletion and inverted duplication.

Results

The patient has a de novo 18p11.31‐18p11.1 inverted duplication with a 6.2 Mb 18p terminal deletion. This rare chromosome imbalance, most likely caused by the U‐type exchange mechanism, resulted in the aberrant phenotype of mental disability, speech delay, seizure, and strabismus. However, the rearrangement was not inherited by her unborn child.

Conclusion

This report added a new type of variation to the spectrum of 18p terminal deletion with inverted duplication, and demonstrated that the maternal chromosome rearrangement discovered in NIPT should not just be consider as an interference factor but also a potential indicator of previously undiscovered pathogenic chromosome structure variations in pregnant women.