Associations among genotype, clinical phenotype, and intracellular localization of trafficking proteins in ARC syndrome
Human Mutation , Volume 33 - Issue 12 p. 1656- 1664
Arthrogryposis-renal dysfunction-cholestasis (ARC) syndrome is a rare autosomal recessive multisystem disorder caused by mutations in vacuolar protein sorting 33 homologue B (VPS33B) and VPS33B interacting protein, apical-basolateral polarity regulator (VIPAR). Cardinal features of ARC include congenital joint contractures, renal tubular dysfunction, cholestasis, severe failure to thrive, ichthyosis, and a defect in platelet alpha-granule biogenesis. Most patients with ARC do not survive past the first year of life. We report two patients presenting with a mild ARC phenotype, now 5.5 and 3.5 years old. Both patients were compound heterozygotes with the novel VPS33B donor splice-site mutation c.1225+5G>C in common. Immunoblotting and complementary DNA analysis suggest expression of a shorter VPS33B transcript, and cell-based assays show that c.1225+5G>C VPS33B mutant retains some ability to interact with VIPAR (and thus partial wild-type function). This study provides the first evidence of genotype-phenotype correlation in ARC and suggests that VPS33B c.1225+5G>C mutation predicts a mild ARC phenotype. We have established an interactive online database for ARC (https://grenada.lumc.nl/LOVD2/ARC) comprising all known variants in VPS33B and VIPAR. Also included in the database are 15 novel pathogenic variants in VPS33B and five in VIPAR.
|Cholestasis, HOPS complex, Ostopenia, Recycling endosomes, VIPAR, VPS33B|
|Organisation||Department of Pediatrics|
Smith, H, Galmes, R, Gogolina, E, Straatman-Iwanowska, A, Reay, E, Banushi, B, … Gissen, P. (2012). Associations among genotype, clinical phenotype, and intracellular localization of trafficking proteins in ARC syndrome. Human Mutation, 33(12), 1656–1664. doi:10.1002/humu.22155