Desbuquois syndrome is a heterogeneous rare type of skeletal dysplasia with a prevalence of less than 1 in 1,000,000 individuals. It is characterized by short-limbed dwarfism, dysmorphic facial features, and severe joint laxity. Two types have been recognized depending on the presence of distinctive carpal and phalangeal features. Mutations in the calcium activated nucleotidase 1 (CANT1) have been found to be responsible for type I and lately, for the Kim type of Desbuquois dysplasia. In addition, a number of Desbuquois dysplasia type II patients have been attributed to mutations in xylosyltransferase 1, encoded by the XYLT1 gene, an enzyme that catalyzes the transfer of UDP-xylose (a marker of cartilage destruction) to serine residues of an acceptor protein, essential for the biosynthesis of proteoglycans. We report here a patient with features consistent with Desbuquois dysplasia II including short long bones, flat face, mild monkey wrench appearance of the femoral heads. Whole exome sequencing revealed a novel homozygous duplication of a single nucleotide in XYLT1 gene (c.2169dupA). This variant is predicted to result in a frame-shift and stop codon p.(Val724Serfs*10) within the xylosyltransferase catalytic domain. Immunoflourescence staining of HeLa cells transfected with mutated XYLT1 plasmids constructs of the current as well as the previously reported missense mutations (c.1441C>T, p.(Arg481Trp) and c.1792C>T, p.(Arg598Cys)), revealed aberrant subcellular localization of the enzyme compared to wild-type, suggesting endoplasmic reticulum retention of these mutants as the likely mechanism of disease.
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http://dx.doi.org/10.1002/ajmg.a.38244 | DOI Listing |
Am J Med Genet A
December 2024
Department of Pediatric Genetics, Hacettepe University, Ankara, Turkiye.
Multiple epiphyseal dysplasia (MED) is a heterogeneous group of chondrodysplasia characterized by arthralgia, early onset osteoarthropathy, and the radiographic findings of small, flat, and irregular-shaped epiphyses. Some patients with MED have mild short stature as well. MED is genetically heterogeneous caused by pathogenic variants in COMP, MATN3, COL9A1, COL9A2, COL9A3, and SLC26A2.
View Article and Find Full Text PDFBiomolecules
August 2024
Centre for Inherited Diseases, Department of Research, Fondazione IRCCS Policlinico San Matteo, 27100 Pavia, Italy.
Int J Mol Sci
September 2024
Department of Pharmacotherapy and Pharmaceutical Care, Faculty of Pharmacy, Medical University of Warsaw, Banacha 1 Str., 02-097 Warsaw, Poland.
Biomedicines
March 2024
Institut für Laboratoriums- und Transfusionsmedizin, Herz- und Diabeteszentrum Nordrhein-Westfalen, Universitätsklinik der Ruhr-Universität Bochum, Georgstraße 11, 32545 Bad Oeynhausen, Germany.
Desbuquois dysplasia type 2 (DBQD2) and spondylo-ocular syndrome (SOS) are autosomal recessive disorders affecting the extracellular matrix (ECM) and categorized as glycosaminoglycan (GAG) linkeropathies. Linkeropathies result from mutations within glycosyltransferases involved in the synthesis of the tetrasaccharide linker, a linker between the core protein of proteoglycan (PG) and GAG. DBQD2 and SOS are caused by the isolated mutations of the xylosyltransferase (XT) isoforms.
View Article and Find Full Text PDFCell Death Dis
June 2023
UMR 7365 CNRS-University of Lorraine, Biopôle, Faculty of Medicine, BP 20199, 54505, Vandoeuvre-lès-Nancy, CEDEX, France.
Genetic mutations in the Xylt1 gene are associated with Desbuquois dysplasia type II syndrome characterized by sever prenatal and postnatal short stature. However, the specific role of XylT-I in the growth plate is not completely understood. Here, we show that XylT-I is expressed and critical for the synthesis of proteoglycans in resting and proliferative but not in hypertrophic chondrocytes in the growth plate.
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