RT Journal Article SR Electronic T1 Use of a rare disease registry for establishing phenotypic classification of previously unassigned GLA variants: a consensus classification system by a multispecialty Fabry disease genotype–phenotype workgroup JF Journal of Medical Genetics JO J Med Genet FD BMJ Publishing Group Ltd SP 542 OP 551 DO 10.1136/jmedgenet-2019-106467 VO 57 IS 8 A1 Dominique P Germain A1 João Paulo Oliveira A1 Daniel G Bichet A1 Han-Wook Yoo A1 Robert J Hopkin A1 Roberta Lemay A1 Juan Politei A1 Christoph Wanner A1 William R Wilcox A1 David G Warnock YR 2020 UL http://jmg.bmj.com/content/57/8/542.abstract AB Background Fabry disease (α-galactosidase deficiency) is an X-linked genetic disease caused by a variety of pathogenic GLA variants. The phenotypic heterogeneity is considerable, with two major forms, classic and later-onset disease, but adjudication of clinical phenotype is currently lacking for many variants. We aimed to determine consensus phenotypic classification for previously unclassified GLA variants from the GLA-specific fabry-database.org database.Methods A Fabry disease genotype–phenotype workgroup developed a five-stage iterative system based on expert clinical assessment, published literature and clinical evidence of pathogenicity using a 2-point scoring system based on clinical hallmarks of classic disease. Kaplan–Meier (KM) analysis of severe clinical event-free survival was used as final validation. Results were compared with those from web-based disease databases and in silico pathogenicity prediction programmes.Results Final consensus on classifications of ‘pathogenic’ was achieved for 32 of 33 GLA variants (26 ‘classic’ phenotype, 171 males; 6 ‘later-onset’ phenotype, 57 males). One variant remained of uncertain significance. KM curves were similar for the known fabry-database.org database phenotypes and when workgroup consensus classifications were added, and the curves retained the same separation between ‘classic’ and ‘later-onset’ phenotypes.Conclusion The iterative system implemented by a Fabry disease genotype–phenotype workgroup achieved phenotypic classifications for variants that were previously unclassified. Clinical pathogenicity associated with a particular GLA variant defined in affected males appears to have predictive value and also generally correlates with risk for affected females. The newly established classifications can be of benefit to the clinical care of Fabry patients harbouring these variants.