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Microcephalic primordial dwarfism (MPD) is a group of rare single-gene disorders characterized by the extreme reduction in brain and body size from early development onwards. Proteins encoded by MPD-associated genes play important roles in fundamental cellular processes, notably genome replication and repair. Here we report the identification of four MPD individuals with biallelic variants in DNA2, which encodes an adenosine triphosphate (ATP)-dependent helicase/nuclease involved in DNA replication and repair. We demonstrate that the two intronic variants (c.1764-38_1764-37ins(53) and c.74+4A>C) found in these individuals substantially impair DNA2 transcript splicing. Additionally, we identify a missense variant (c.1963A>G), affecting a residue of the ATP-dependent helicase domain that is highly conserved between humans and yeast, with the resulting substitution (p.Thr655Ala) predicted to directly impact ATP/ADP (adenosine diphosphate) binding by DNA2. Our findings support the pathogenicity of these variants as biallelic hypomorphic mutations, establishing DNA2 as an MPD disease gene.
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http://dx.doi.org/10.1002/humu.23776 | DOI Listing |
J Hum Genet
September 2025
Department of Neuromuscular Research, National Institute of Neuroscience, National Center of Neurology and Psychiatry (NCNP), Tokyo, Japan.
GNE myopathy is an autosomal recessive distal myopathy resulting from biallelic pathogenic variants in the GNE gene, a key enzyme in sialic acid biosynthesis. Although most pathogenic variants are missense variants, recent advances have enabled the identification of copy number variations, deep intronic variants, and regulatory changes in the promoter region, significantly enhancing diagnostic accuracy. Progress in genetic diagnostics now allows detection of rare and complex variants.
View Article and Find Full Text PDFJACC Case Rep
September 2025
Department of Internal Medicine, Denia Hospital, Alicante, Spain.
Background: Propionic acidemia (PA) is a rare autosomal recessive metabolic disorder, typically presenting in infancy. Cardiac involvement in adults is uncommon and underrecognized.
Case Summary: A previously healthy 20-year-old man suffered an out-of-hospital cardiac arrest caused by ventricular fibrillation.
Mol Genet Metab
September 2025
Greenwood Genetic Center, Greenwood, SC 29646, United States of America. Electronic address:
Numerous genetic conditions are represented within the biochemical pathway for de novo cholesterol biosynthesis. Among the emerging disease-gene associations is CYP51A1, encoding a lanosterol demethylase enzyme. Biallelic variants in CYP51A1 have been associated with congenital cataracts and variable liver disease but an appreciation of genotype/phenotype correlation is lacking due to the limited number of patients described.
View Article and Find Full Text PDFOphthalmol Sci
July 2025
Japan Community Healthcare Organization, Tokyo, Japan.
Purpose: We report the efficacy and safety of voretigene neparvovec (VN) as an adeno-associated viral vector-based gene therapy for Japanese patients with inherited retinal dystrophy caused by biallelic pathogenic variants (-retinopathy).
Design: Open-label, single arm, phase III clinical trial.
Participants: Four subjects were recruited based on the following criteria: (1) a clinical and molecular genetic diagnosis of -retinopathy; (2) age ≥4 years; (3) a best-corrected VA (BCVA) worse than 20/60 or a visual field (VF) <20° by a III4e isopter or equivalent; and (4) sufficient viable retinal cells by OCT or ophthalmoscopy.
We recently showed that mutations in and , two genes that are transcribed into small nuclear RNA (snRNA) components of the major spliceosome, are prevalent causes of dominant neurodevelopmental disorders (NDDs). By genetic association comparing 12,776 NDD cases with 56,064 controls, we now demonstrate the existence of a recessive form of syndrome that, in England, is even more common than the dominant form. We inferred log Bayes factors for dominant and recessive models of association of 14.
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