iduronate and Syndrome

Heparan sulfate belongs to the group of glycosaminoglycans (GAGs), highly sulfated linear polysaccharides. Heparan sulfate 2-O-sulfotransferase 1 (HS2ST1) is one of several specialized enzymes required for heparan sulfate synthesis and catalyzes the transfer of the sulfate groups to the sugar moiety of heparan sulfate. We report bi-allelic pathogenic variants in HS2ST1 in four individuals from three unrelated families. Affected individuals showed facial dysmorphism with coarse face, upslanted palpebral fissures, broad nasal tip, and wide mouth, developmental delay and/or intellectual disability, corpus callosum agenesis or hypoplasia, flexion contractures, brachydactyly of hands and feet with broad fingertips and toes, and uni- or bilateral renal agenesis in three individuals. HS2ST1 variants cause a reduction in HS2ST1 mRNA and decreased or absent heparan sulfate 2-O-sulfotransferase 1 in two of three fibroblast cell lines derived from affected individuals. The heparan sulfate synthesized by the individual 1 cell line lacks 2-O-sulfated domains but had an increase in N- and 6-O-sulfated domains demonstrating functional impairment of the HS2ST1. As heparan sulfate modulates FGF-mediated signaling, we found a significantly decreased activation of the MAP kinases ERK1/2 in FGF-2-stimulated cell lines of affected individuals that could be restored by addition of heparin, a GAG similar to heparan sulfate. Focal adhesions in FGF-2-stimulated fibroblasts of affected individuals concentrated at the cell periphery. Our data demonstrate that a heparan sulfate synthesis deficit causes a recognizable syndrome and emphasize a role for 2-O-sulfated heparan sulfate in human neuronal, skeletal, and renal development.

Topics: Adolescent; Alleles; Biopsy; Bone and Bones; Child; Child, Preschool; Corpus Callosum; Developmental Disabilities; Extracellular Matrix; Extracellular Signal-Regulated MAP Kinases; Family Health; Female; Fibroblasts; Genetic Variation; Heparitin Sulfate; Humans; Iduronic Acid; Infant, Newborn; Kidney; Male; Pedigree; Phenotype; Sulfotransferases; Syndrome; Urogenital Abnormalities

The properties of [35S]sulfate-labeled proteoglycans secreted by normal human skin fibroblasts were compared with those synthesized by fibroblasts from three patients with Coffin-Lowry syndrome. 60-80% of secreted radioactive macromolecules from normal fibroblasts were eluted from a Sepharose CL-4B column with a mean Kav-value of 0.56 (pool 2); 3-10% of the radioactivity appeared in the exclusion volume of the column (pool 1). In contrast, 17-60% of the proteoglycans from the patients were found in the void volume. The bulk of remaining material was eluted with a mean Kav-value of 0.47. Pool 2 glycan chains from two patients exhibited an increased hydrodynamic size. Pool 1 from normal cells contained predominantly a glucuronic acid-rich proteodermatan sulfate, iduronic acid amounting for approximately 20% of glucuronic acid. In the respective proteodermatan sulfate from the patients, the relative iduronic acid content was at least 33% of that of glucuronic acid. Pool 2 material of all cell lines was characterized predominantly as iduronic acid-rich proteodermatan sulfate. In the proteoglycans from two patients the content of chondroitin 4-sulfate-derived disaccharides was increased at the expense of 6-sulfated chondroitin disaccharides. Native proteoglycans from the patients were less efficiently endocytosed by fibroblasts than their normal counterparts. Coffin-Lowry fibroblasts had a normal capability to synthesize glycosaminoglycan chains on an artificial acceptor, p-nitrophenyl-beta-D-xyloside. They were also normal in 3'-phosphoadenylylsulfate: chondroitin 4- and 6-sulfotransferase activities.

Topics: Abnormalities, Multiple; Adult; Bone and Bones; Cells, Cultured; Child, Preschool; Chondroitin; Dermatan Sulfate; Fibroblasts; Glucuronates; Glucuronic Acid; Humans; Iduronic Acid; Intellectual Disability; Male; Proteoglycans; Sex Factors; Skin; Skin Diseases; Syndrome