RT Journal Article SR Electronic T1 WFS1 protein expression correlates with clinical progression of optic atrophy in patients with Wolfram syndrome JF Journal of Medical Genetics JO J Med Genet FD BMJ Publishing Group Ltd SP jmedgenet-2020-107257 DO 10.1136/jmedgenet-2020-107257 A1 Kun Hu A1 Malgorzata Zatyka A1 Dewi Astuti A1 Nicola Beer A1 Renuka P Dias A1 Archana Kulkarni A1 John Ainsworth A1 Benjamin Wright A1 Anna Majander A1 Patrick Yu-Wai-Man A1 Denise Williams A1 Timothy Barrett YR 2021 UL http://jmg.bmj.com/content/early/2021/05/18/jmedgenet-2020-107257.abstract AB Background Wolfram syndrome (WFS) is a rare disorder characterised by childhood-onset diabetes mellitus and progressive optic atrophy. Most patients have variants in the WFS1 gene. We undertook functional studies of WFS1 variants and correlated these with WFS1 protein expression and phenotype.Methods 9 patients with a clinical diagnosis of WFS were studied with quantitative PCR for markers of endoplasmic reticulum (ER) stress and immunoblotting of fibroblast protein extracts for WFS1 protein expression. Luciferase reporter assay was used to assess ATF-6 dependent unfolded protein response (UPR) activation.Results 6 patients with compound heterozygous nonsense mutations in WFS1 had no detectable WFS1 protein expression; 3 patients with missense variants had 4%, 45% and 48% WFS1 protein expression. One of these also had an OPA1 mutation and was reclassified as autosomal dominant optic atrophy-plus syndrome. There were no correlations between ER stress marker mRNA and WFS1 protein expression. ERSE-luciferase reporter indicated activation of the ATF6 branch of UPR in two patients tested. Patients with partial WFS1 expression showed milder visual acuity impairment (asymptomatic or colour blind only), compared with those with absent expression (registered severe vision impaired) (p=0.04). These differences remained after adjusting for duration of optic atrophy.Conclusions Patients with WFS who have partial WFS1 protein expression present with milder visual impairment. This suggests a protective effect of partial WFS1 protein expression on the severity and perhaps progression of vision impairment and that therapies to increase residual WFS1 protein expression may be beneficial.All data relevant to the study are included in the article or uploaded as supplementary information. All data relevant to the study are included in the article.