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Background: Classical homocystinuria (HCU) is a monogenic disease caused by the deficient activity of cystathionine β-synthase (CβS). The objective of this study was to identify the CBS mutations in Brazilian patients with HCU.
Methods: gDNA samples were obtained for 35 patients (30 families) with biochemically confirmed diagnosis of HCU. All exons and exon-intron boundaries of CBS gene were sequenced. Gene expression analysis by qRT-PCR was performed in six patients. Novel missense point mutations were expressed in E. coli by site-directed mutagenesis.
Results: Parental consanguinity was reported in 16 families, and pyridoxine responsiveness in five (15%) patients. Among individuals from the same family, all presented the same phenotype. Both pathogenic mutations were identified in 29/30 patients. Twenty-one different mutations were detected in nine exons and three introns; being six common mutations. Most prevalent were p.Ile278Thr (18.2%), p.Trp323Ter (11.3%), p.Thr191Met (11.3%), and c.828+1G>A (11.3%). Eight novel mutations were found [c.2T>C, c.209+1delG, c.284T>C, c.329A>T, c.444delG, c.864_868delGAG c.989_991delAGG, and c.1223+5G>T]. Enzyme activity in E. coli-expressed mutations was 1.5% for c.329A>T and 17.5% for c.284T>C. qRT-PCR analysis revealed reduced gene expression in all evaluated genotypes: [c.209+1delG; c.572C>T]; [c.2T>C; c.828+1G>A]; [c.828+1G>A; c.1126G>A]; [c.833T>C; c.989_991delAGG]; [c.1058C>T; c.146C>T]; and [c.444delG; c.444delG]. The expected phenotype according to the genotype (pyridoxine responsiveness) matched in all cases.
Conclusions: Most patients studied were pyridoxine nonresponsive and presented early manifestations, suggesting severe phenotypes. Many private mutations were observed, but the four most prevalent mutations together accounted for over 50% of mutated alleles. A good genotype-phenotype relationship was observed within families and for the four most common mutations.
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http://dx.doi.org/10.1002/mgg3.342 | DOI Listing |
JCI Insight
September 2025
Department of Pharmacology, University of Michigan, Ann Arbor, United States of America.
Cardiac hypertrophy is a common adaptation to cardiovascular stress and often a prelude to heart failure. We examined how S-palmitoylation of the small GTPase, Ras-related C3 botulinum toxin substrate 1 (Rac1), impacts cardiomyocyte stress signaling. Mutation of the cysteine-178 palmitoylation site impaired activation of Rac1 when overexpressed in cardiomyocytes.
View Article and Find Full Text PDFJ Clin Invest
September 2025
Department of Genetics, Research Institute of Environmental Medicine, Nagoya University, Nagoya, Japan.
Proc Natl Acad Sci U S A
September 2025
Department of Medical and Molecular Genetics, Indiana University School of Medicine, Indianapolis, IN 46202.
Retinal ganglion cells (RGCs) are highly compartmentalized neurons whose long axons serve as the sole connection between the eye and the brain. In both injury and disease, RGC degeneration occurs in a similarly compartmentalized manner, with distinct molecular and cellular responses in the axonal and somatodendritic regions. The goal of this study was to establish a microfluidic-based platform to investigate RGC compartmentalization in both health and disease states.
View Article and Find Full Text PDFJ Biomol Struct Dyn
September 2025
Department of Biology, Faculty of Science, University of Sistan and Baluchestan, Zahedan, Iran.
Acetylesterase, produced by , plays a crucial role in deacetylating hemicellulose during pulp production. Thermostable variants of this enzyme, although rare, can significantly enhance industrial efficiency by retaining activity at high temperatures. This research aims to design a thermostable variant of acetylesterase from (EC 3.
View Article and Find Full Text PDFMetabolomics
September 2025
Laboratoire de Biochimie et Biologie Moléculaire, Centre Hospitalier Universitaire, Angers, France.
Introduction: The definition of Leber's hereditary optic neuropathy (LHON) does not take into account a preclinical phase during which the thickness of retinal nerve fiber layer (RNFL) is increased, prior to optic nerve atrophy, reducing the chances of visual recovery.
Objectives: Search for a metabolomic signature characterizing this preclinical phase and identify biomarkers predicting the risk of LHON onset.
Methods And Results: The blood and tear metabolomic profiles of 90 asymptomatic LHON mutation carriers followed for one year will be explored as a function of RNFL thickness and compared to those of a healthy control.