Genotype-Based Severity Scoring System in Wolfram Syndrome: Correlation with Onset of Cardinal Symptoms and WFS1 Gene Variant Types
Liam Oiknine, Abby F. Tang, Evan M. LeeiD, Nila PalaniappaniD, Megha VermaiD, Kasra A. Vand, Sahiti Somalraju, Sarath Chandra JangaiD, Fumihiko UranoiD
Abstract
Wolfram syndrome is a rare genetic disorder characterized by antibody-negative early-onset atypical diabetes mellitus, optic nerve atrophy, sensorineural hearing loss, diabetes insipidus (arginine vasopressin deficiency), and progressive neurodegeneration, with significant variability in disease severity. We assessed the accuracy of a genotype-based severity scoring system to predict the onset of cardinal symptoms in Wolfram syndrome. This system is based on the type of WFS1 variants (in-frame or out-of-frame) and their location relative to transmembrane domains. Severity scores were assigned to 324 patients with documented onset ages for diabetes mellitus, optic atrophy, hearing loss, and central diabetes insipidus (arginine-vasopressin deficiency). Our analysis revealed a clear association between the proposed genetic severity scoring system and earlier onset of diabetes mellitus and optic atrophy. Patients with in-frame variants outside transmembrane domains exhibited milder symptoms, especially WFS1 c.1672C>T (p.Arg558Cys) variant, whereas those with out-of-frame variants showed the earliest onset. Severity scores 3 and 4 did not follow the expected progression, suggesting that transmembrane domain involvement in both alleles may result in greater severity. To independently evaluate the proposed model, we developed a computational framework employing the classification rubric, which was able to confirm that the six-class system can be automatically annotated with 94.4% accuracy. Closer examination of the 7 cases that disagreed with the manual annotation helped improve the annotations and our scoring system, to deploy a three-class model, suggesting the value added by our automatic classifier. Taken together, these findings indicate that the genotype-based severity score is most informative for diabetes mellitus, more modestly informative for optic atrophy, and not currently useful for predicting the onset of hearing loss or diabetes insipidus. Because the analysis is based on observed events without time-to-event censoring and the three-tier consolidation is a post hoc summary of the same dataset, the results should be regarded as exploratory and hypothesis-generating rather than as a fully validated clinical prediction tool, while still offering useful insight into the genotype-related progression of Wolfram syndrome to guide future study.
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In-depth summary
Claude Opus 5.5 · xhigh effort · 8 Nov 2026 · from the full text of version 2 (31 May 2026) · CC BY 4.0
Higher WFS1 genotype scores (variant frame, transmembrane location) tracked earlier diabetes mellitus and optic atrophy onset in 324 Wolfram patients, not hearing loss or diabetes insipidus.
Wolfram syndrome severity varies widely, and earlier work tied WFS1 frameshift/nonsense variants and in-frame variants inside transmembrane domains to earlier symptom onset. This study combines both features into a six-level genotype score and tests whether it predicts onset of the cardinal manifestations in a large registry cohort.
Key results
ShownThe genotype severity score tracked diabetes mellitus onset: higher scores had earlier onset, except score 3. Merging scores into Mild (1-2), Moderate (3-4) and Severe (5-6) tiers gave significant separation between consecutive tiers.
Bonferroni-corrected Dunn's test: score 2 vs 3 p = 0.008128, score 4 vs 5 p = 0.001535. Tier medians were 9.0, 6.5 and 4.6 years (Mild, Moderate, Severe). Consecutive-tier p-values were 0.011445 (Mild to Moderate) and 5.25 × 10^−6 (Moderate to Severe). Based on 324 patients with diabetes mellitus onset data. · Data Analysis; Diabetes Mellitus; Figure legends
SuggestedOptic atrophy onset followed a weaker, less consistent trend with score. No pair of adjacent individual scores differed significantly, though the consolidated tiers ordered onset ages in the expected direction.
Score 3 vs 4 was reported as near significant (p = 0.059694); consolidated Mild, Moderate and Severe medians were 14.0, 11.0 and 9.0 years; no tier-level p-values reported for optic atrophy; 306 patients with optic atrophy onset data. · Data Analysis; Optic Atrophy; Figure legends
SuggestedHearing loss and diabetes insipidus onset ages showed no relationship to the severity score. Both distributions had a similar shape, with earlier onset in scores 2 and 5.
No significant difference between any adjacent score groups and no consistent pattern; onset data were available for 195 (hearing loss) and 149 (diabetes insipidus) patients. · Data Analysis; Hearing Loss and Diabetes Insipidus; Figure legends
SuggestedScore 3 (both in-frame variants within transmembrane domains) behaved as more severe than score 4 (one truncating plus one in-frame non-transmembrane variant), contrary to the intended ordering.
Score 3 had earlier median onset than score 4 for diabetes mellitus, optic atrophy and hearing loss. The authors propose that transmembrane disruption on both alleles impairs folding and topology more than one truncating allele paired with a partly functional one; this mechanism was not tested. · Diabetes Mellitus; Optic Atrophy; 4. Discussion
ClaimedIn-frame variants outside transmembrane domains, especially c.1672C>T (p.Arg558Cys), were linked to milder disease, and out-of-frame variants to the earliest onset.
Stated in the abstract only; the results sections report no variant-level onset statistics for c.1672C>T, and score 6 is pooled with score 5 in the Severe tier (diabetes mellitus median 4.6 years). · Abstract; Diabetes Mellitus
Methods, data and reproducibility
Retrospective genotype-phenotype analysis. Patients with biallelic WFS1 pathogenic variants were binned into six severity scores by variant frame (in-frame missense/indel vs frameshift/nonsense) and transmembrane-domain location. Onset ages for each symptom were then compared using Kruskal-Wallis and Bonferroni-corrected Dunn's tests.
- Wolfram syndrome registry records (Washington University International Registry and Clinical Study) plus patient case reports, filtered to biallelic WFS1 pathogenic variant carriers · human · n = more than 400 patients sampled
- Per-symptom analysis subsets with a numeric onset age for diabetes mellitus (DM), optic atrophy (OA), hearing loss (HL) or diabetes insipidus (DI) · human · n = 324 (DM), 306 (OA), 195 (HL), 149 (DI)
- Methods & tools
- Kruskal-Wallis test, Dunn's test with Bonferroni correction, Six-level genotype-based WFS1 severity score, WFS1 variant classification: in-frame (missense, indel) vs out-of-frame (frameshift, nonsense), Transmembrane domain location assignment for WFS1 variants
- Reproducibility gaps
- Clinical data are not public because of patient privacy and IRB #201107067 restrictions; deidentified data are available from the corresponding author on reasonable request under a data use agreement. No analysis code or software versions are reported.
Limitations (6)
- The cohort is likely underpowered for hearing loss and diabetes insipidus (onset recorded for 195 and 149 patients), limiting detection of genotype-phenotype links for these manifestations; continued registry recruitment is needed. · stated by the authors
- Score 3 (biallelic in-frame transmembrane variants) appeared more severe than score 4, contradicting the intended ordering; the authors suggest repositioning these scores, though both fall within the Moderate tier. · stated by the authors
- Optic atrophy may be recognized only gradually after it begins, so recorded onset ages may carry reporting bias. · stated by the authors
- Variant type and transmembrane location alone do not capture variant-specific functional effects; the authors propose adding endoplasmic reticulum (ER) stress assays, biomarkers (C-peptide, neurofilament light chain) and AlphaFold structural modeling to refine the score. · stated by the authors
- Patients without a recorded onset age were excluded, outliers were dropped from graphs, and no time-to-event handling of not-yet-affected patients is described; this could bias onset medians, especially for younger patients with mild genotypes. · noted in this summary
- The provided text reports no per-score sample sizes, no covariate adjustment (e.g., sex, diagnosis era), no external validation cohort and no measure of predictive accuracy for individual patients. · noted in this summary
Who should read:Read this if you counsel Wolfram syndrome families, need genotype-based stratification for WFS1 trials, or study how variant frame and transmembrane location shape onset of disease symptoms.
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