ZNF142 mutation causes sex-dependent neurologic disorder

BACKGROUND

Sex-specific predilection in neurological diseases caused by mutations in autosomal genes is a phenomenon whose molecular basis is poorly understood. We studied females of consanguineous Bedouin kindred presenting with severe global developmental delay and epilepsy.

METHODS

Linkage analysis, whole exome sequencing, generation of CRISPR/cas9 knock-in mice, mouse behaviour and molecular studies RESULTS: Linkage analysis and whole exome sequencing studies of the affected kindred delineated a ~5 Mbp disease-associated chromosome 2q35 locus, containing a novel homozygous frameshift truncating mutation in ZNF142, in line with recent studies depicting similar ZNF142 putative loss-of-function human phenotypes with female preponderance. We generated knock-in mice with a truncating mutation adjacent to the human mutation in the mouse ortholog. Behaviour studies of homozygous Zfp142R1508* mice showed significant phenotype only in mutant females, with learning and memory deficits, hyperactivity and aberrant loss of fear of open spaces. Bone marrow and spleen of homozygous Zfp142R1508* mice showed depletion of lymphoid and haematopoietic cells, mostly in females. RT-PCR showed lower expression of Zpf142 in brain compartments of female versus male wild-type mice. RNA-seq studies of hippocampus, hypothalamus, cortex and cerebellum of female wild-type versus homozygous Zfp142R1508* mice demonstrated differentially expressed genes. Notably, expression of Taok1 in the cortex and of Mllt6 in the hippocampus was downregulated in homozygous Zfp142R1508* mice. Taok1 mutations have been associated with aberrant neurodevelopment and behaviour. Mllt6 expression is regulated by sex hormones and Mllt6 null-mutant mice present with haematopoietic, immune system and female-specific behaviour phenotypes.

CONCLUSION

ZNF142 mutation downregulates Mllt6 and Taok1, causing a neurodevelopmental phenotype in humans and mice with female preponderance.

VARista: a free web platform for streamlined whole-genome variant analysis across T2T, hg38, and hg19

With the increasing importance of genomic data in understanding genetic diseases, there is an essential need for efficient and user-friendly tools that simplify variant analysis. Although multiple tools exist, many present barriers such as steep learning curves, limited reference genome compatibility, or costs. We developed VARista, a free web-based tool, to address these challenges and provide a streamlined solution for researchers, particularly those focusing on rare monogenic diseases. VARista offers a user-centric interface that eliminates much of the technical complexity typically associated with variant analysis. The tool directly supports VCF files generated using reference genomes hg19, hg38, and the emerging T2T, with seamless remapping capabilities between them. Features such as gene summaries and links, tissue and cell-specific gene expression data for both adults and fetuses, as well as automated PCR design and integration with tools such as SpliceAI and AlphaMissense, enable users to focus on the biology and the case itself. As we demonstrate, VARista proved effective in narrowing down potential disease-causing variants, prioritizing them effectively, and providing meaningful biological context, facilitating rapid decision-making. VARista stands out as a freely available and comprehensive tool that consolidates various aspects of variant analysis into a single platform that embraces the forefront of genomic advancements. Its design inherently supports a shift in focus from technicalities to critical thinking, thereby promoting better-informed decisions in genetic disease research. Given its unique capabilities and user-centric design, VARista has the potential to become an essential asset for the genomic research community. https://VARista.link.

De-novo "germline second hit" loss-of-heterozygosity RBP3 deletion mutation causing recessive high myopia

Knudson's "two hit" hypothesis, mostly associated with cancer, relates to a primary heterozygous germline mutation complemented by a somatic mutation in the second allele. When the somatic "second hit" is a deletion mutation, the heterozygosity due to the first hit is lost ("loss of heterozygosity"). As the rate of germline mutations is almost two orders of magnitude lower than that of somatic mutations, de-novo germline mutations causing autosomal recessive diseases in carriers of inherited heterozygous mutations are not common. We delineate a case of high myopia presenting at infancy with mild diminution of retinal responses. Exome sequencing identified a paternally inherited apparently homozygous missense mutation in RBP3. Chromosomal microarrays delineated a de-novo germline heterozygous deletion encompassing RBP3, verified through revision of WES data. Thus, we demonstrate an inherited RBP3 missense mutation complemented by a de-novo germline RBP3 deletion, causing loss of heterozygosity of the inherited mutation. We describe a novel RBP3 missense mutation, report the first isolated RBP3 deletion, and demonstrate infantile high myopia as an initial presentation of RBP3 disease. Notably, we highlight de-novo germline deletion mutations causing "loss of heterozygosity" of inherited heterozygous mutations, culminating in autosomal recessive diseases, and discuss the scarce literature.

Hyperinsulinism/hyperammonemia syndrome caused by biallelic SLC25A36 mutation

Hyperinsulinism/hyperammonemia (HI/HA) syndrome has been known to be caused by dominant gain-of-function mutations in GLUD1, encoding the mitochondrial enzyme glutamate dehydrogenase. Pathogenic GLUD1 mutations enhance enzymatic activity by reducing its sensitivity to allosteric inhibition by GTP. Two recent independent studies showed that a similar HI/HA phenotype can be caused by biallelic mutations in SLC25A36, encoding pyrimidine nucleotide carrier 2 (PNC2), a mitochondrial nucleotide carrier that transports pyrimidine and guanine nucleotides across the inner mitochondrial membrane: one study reported a single case caused by a homozygous truncating mutation in SLC25A36 resulting in lack of expression of SLC25A36 in patients' fibroblasts. A second study described two siblings with a splice site mutation in SLC25A36, causing reduction of mitochondrial GTP content, putatively leading to hyperactivation of glutamate dehydrogenase. In an independent study, through combined linkage analysis and exome sequencing, we demonstrate in four individuals of two Bedouin Israeli related families the same disease-causing SLC25A36 (NM_018155.3) c.284 + 3A > T homozygous splice-site mutation found in the two siblings. We demonstrate that the mutation, while causing skipping of exon 3, does not abrogate expression of mRNA and protein of the mutant SLC25A36 in patients' blood and fibroblasts. Affected individuals had hyperinsulinism, hyperammonemia, borderline low birth weight, tonic-clonic seizures commencing around 6 months of age, yet normal intellect and no significant other morbidities. Chronic constipation, hypothyroidism, and developmental delay previously described in a single patient were not found. We thus verify that biallelic SLC25A36 mutations indeed cause HI/HA syndrome and clearly delineate the disease phenotype.

CCL24 regulates biliary inflammation and fibrosis in primary sclerosing cholangitis

ˆCCL24 is a pro-fibrotic, pro-inflammatory chemokine expressed in several chronic fibrotic diseases. In the liver, CCL24 plays a role in fibrosis and inflammation, and blocking CCL24 led to reduced liver injury in experimental models. We studied the role of CCL24 in primary sclerosing cholangitis (PSC) and evaluated the potential therapeutic effect of blocking CCL24 in this disease. Multidrug resistance gene 2-knockout (Mdr2-/-) mice demonstrated CCL24 expression in liver macrophages and were used as a relevant experimental PSC model. CCL24-neutralizing monoclonal antibody, CM-101, significantly improved inflammation, fibrosis, and cholestasis-related markers in the biliary area. Moreover, using spatial transcriptomics, we observed reduced proliferation and senescence of cholangiocytes following CCL24 neutralization. Next, we demonstrated that CCL24 expression was elevated under pro-fibrotic conditions in primary human cholangiocytes and macrophages, and it induced proliferation of primary human hepatic stellate cells and cholangiocytes, which was attenuated following CCL24 inhibition. Correspondingly, CCL24 was found to be highly expressed in liver biopsies of patients with PSC. CCL24 serum levels correlated with Enhanced Liver Fibrosis score, most notably in patients with high alkaline phosphatase levels. These results suggest that blocking CCL24 may have a therapeutic effect in patients with PSC by reducing liver inflammation, fibrosis, and cholestasis.

PSMC1 variant causes a novel neurological syndrome

Proteasome 26S, the eukaryotic proteasome, serves as the machinery for cellular protein degradation. It is composed of the 20S core particle and one or two 19S regulatory particles, composed of a base and a lid. To date, several human diseases have been associated with mutations within the 26S proteasome subunits; only one of them affects a base subunit. We now delineate an autosomal recessive syndrome of failure to thrive, severe developmental delay and intellectual disability, spastic tetraplegia with central hypotonia, chorea, hearing loss, micropenis and undescended testes, as well as mild elevation of liver enzymes. None of the affected individuals achieved verbal communication or ambulation. Ventriculomegaly was evident on MRI. Homozygosity mapping combined with exome sequencing revealed a disease‐associated p.I328T PSMC1 variant. Protein modeling demonstrated that the PSMC1 variant is located at the highly conserved putative ATP binding and hydrolysis domain, and is suggested to interrupt a hydrophobic core within the protein. Fruit flies in which we silenced the Drosophila ortholog Rpt2 specifically in the eye exhibited an apparent phenotype that was highly rescued by the human wild‐type PSMC1, yet only partly by the mutant PSMC1, proving the functional effect of the p.I328T disease‐causing variant.

Confirmation of an excess of the high enzyme activity COMT val allele in heroin addicts in a family-based haplotype relative risk study

A previous case control study by Vandenbergh et al. [1997: Am J Med Genet 74:439-442] showed an association between the high activity catechol O-methyltransferase (COMT) polymorphism and polysubstance abuse in a group of North American subjects. In the current study we confirm these results by genotyping 38 Israeli heroin addicts and both parents using a robust family-based haplotype relative risk (HRR) strategy. There is an excess of the val COMT allele (likelihood ratio = 4.48, P = 0.03) and a trend for an excess of the val/val COMT genotype (likelihood ratio = 4.97, P = 0.08, 2 df) in the heroin addicts compared to the HRR control group. We also genotyped an additional 101 nonrelated heroin addicts and 126 control subjects using a case control design and found no significant difference in COMT val allele frequency (25.4% vs. 29.7%, likelihood ratio = 1.04, P = 0.31). A significant difference is observed in COMT allele frequency among the three principal Israeli ethnic groups (Ashkenazi Jewish, non-Ashkenazi Jewish, and Palestinian Arab) in a large group of control subjects we have so far examined (chi-square = 7.9, P = 0.019, df = 2, n = 1,422 alleles) suggesting that population stratification is responsible for our failure to observe an excess of the COMT val allele when using the case-control design.

Pulse transmission and impedance characteristics of a non-uniform circulatory model

In recent years, the technique of non-uniform transmission lines has been utilized in the synthesis of lines feeding antennae from transmitters, thereby maintaining matching over a wide band of frequencies and with varying load. For this reason, an electrical model based on that technique stems from the resemblance between the two systems: in both the feeding medium is non-uniform, and it is necessary to maintain a good response over a wide range of frequencies. Our non-uniform transmission line model of the arterial system, introduced in an earlier publication, supplies comprehensive answers to many questions dealing with the research into this system. Whereas in our earlier model the ohmic resistance R was considered small and not considered in the calculations, it is included in the present study. We have calculated the variation of the input impedance with the frequency and distance from the source, the effect of occluded main branches, augmentation of the pressure wave, the relationship between body size and heart rate and the matching of impedances at large bifurcations. We found that our calculated results agree very well with the quantitative results measured by other investigators in the field.