Biomedical subjects

Rami Abou Jamra

Publications and source records attributed to Rami Abou Jamra.

4 recordsLinked to original sources

PubMed2026

Mutation timing, accumulation, and selection in the male germline shape inheritance risk for developmental disorders.

De novo mutations (DNMs) in the paternal germline are a major cause of developmental disorders, but how mutation timing, paternal age, and spermatogonial selection jointly shape transmissible risk within individual fathers is unclear. We combined trio whole-genome sequencing from 167 families with deep targeted NanoSeq profiling of sperm from 127 fathers of children with confirmed pathogenic DNMs. Transmitted DNM burden and paternal sperm mutation burden, spectra, and selection landscape were indistinguishable from population reference cohorts. Six fathers carried pathogenic early mosaic variants detectable in sperm at variant allele fractions (VAFs) of 0.7%-14.8%, creating individual recurrence-risk outliers. However, early mosaics accounted for ∼8% of the cohort-aggregated pathogenic burden exome-wide, compared with ∼18% from known positively selected drivers and ∼74% from other rare variants accumulating with paternal age. Thus, paternal de novo disease risk is shaped primarily by universal age-associated mutation and selection, while early mosaicism creates uncommon but clinically important high-risk individuals.

DNMs↗

PubMed2026

Evidence supporting the role of GIGYF2 in synapse development and autism.

Autism spectrum disorder (ASD) is a heterogeneous condition in which genetically defined subtypes offered insights into underlying biological mechanisms and potential targeted treatments. Here, we investigate the clinical and pathogenic significance of GIGYF2 variants in ASD through an integrated approach combining clinical genetics, conditional knockout (cKO) mouse models, neurobiology, and molecular studies. Through targeted sequencing, large-scale genomic data analysis of neurodevelopmental disorder cohorts, and international collaborations, we identified ten affected individuals from eight families harboring de novo or dominantly inherited likely gene-disruptive (LGD) variants and 13 affected individuals from 13 families with de novo missense variants in GIGYF2. Clinical characterization of 16 probands with GIGYF2 variants revealed common features, including ASD, language problems, intellectual disability, and anxiety. In a Gigyf2 cKO mouse model, we observed pronounced autistic-like behaviors, cognitive deficits, and anxiety-like behaviors, mirroring phenotypes observed in affected individuals. Mechanistically, Gigyf2 deficiency disrupted synaptic homeostasis, as evidenced by altered spine density and miniature excitatory postsynaptic currents, and impaired IGF-1R/mTOR signaling, along with dysregulation of synapse-related genes such as Nrp2. Pharmacological inhibition of mTOR with rapamycin or Torin1, as well as Nrp2 knockdown rescued synaptic defects in Gigyf2 KO neurons. These findings define a novel ASD subtype associated with GIGYF2 variants and establish GIGYF2 as a key regulator of synaptic development and function, implicating GIGYF2 dysfunction in ASD pathogenesis and highlighting the IGF-1R/mTOR pathway as a potential therapeutic target for GIGYF2-related ASD subtype.

Journal Article↗

PubMed2025

Pathogenic XPO1 variants cause a dominant neurodevelopmental disorder.

PURPOSE: XPO1 functions in key cellular processes, including nucleo-cytoplasmic export and mitosis. The gene is deleted in a subset of patients with the 2p15p16.1 microdeletion syndrome; however, no monogenic XPO1-related disorder has been described to date. METHODS: We collected clinical data of individuals with de novo XPO1 variants through online matchmaking. We used Drosophila to study XPO1 function in development and habituation learning. RESULTS: A total of 22 individuals met the criteria to be included in the main study cohort. Of these, half have putative loss-of-function variants, and half have coding variants (10 missense and 1 in-frame deletion variant). We found an overlapping phenotype, consistent with a monogenic neurodevelopmental disorder. We demonstrate XPO1 functions in development by ubiquitous and neuron-specific knockdown in Drosophila. GABAergic neuron specific knockdown flies demonstrated impaired habituation. CONCLUSION: Our results establish XPO1 as a novel dominant monogenic neurodevelopmental disorder gene and demonstrate a central role for XPO1 in development.

Exportin 1 Protein↗

PubMed2024

Upregulation versus loss of function of NTRK2 in 44 affected individuals leads to 2 distinct neurodevelopmental disorders.

PURPOSE: Heterozygous pathogenic variants in NTRK2 (HGNC: 8032) have been associated with global developmental delay. However, only scattered cases have been described in small or general studies. The aim of our work was to consolidate our understanding of NTRK2-related disorders and to delineate the clinical presentation. METHODS: We reported an extended cohort of 44 affected individuals, of whom 19 are from the literature and 25 were previously unreported. RESULTS: Our analysis led to splitting the cohort into 2 entities. CONCLUSION: One group had variants in the cholesterol-binding motif of the transmembrane domain, with most of these being the recurrent variant c.1301A>G p.(Tyr434Cys). These variants probably lead to upregulation of tropomyosin receptor kinase B activity and to a severe phenotype of developmental delay/intellectual disability, muscular hypotonia, therapy-refractory epilepsy, visual impairment and blindness, and feeding difficulties. The second group had truncating variants or variants that presumably disturb the 3D structure of the protein leading to loss of function. These individuals had a remarkably milder phenotype of developmental delay, obesity, and hyperphagia.

Humans↗