Abstract
We scoped the question: For GJB2, do ClinVar-pathogenic variants sit at lower gnomAD population frequency than benign ones? This question requires (1) retrieving ClinVar variants classified as pathogenic or benign for gene GJB2, (2) joining them to gnomAD allele-frequency data, and (3) statistically comparing the allele-frequency distributions of the two pathogenicity classes. The capability gate selected the population_allele_freq reference template, which tests whether a single variant or region differs in allele frequency across 1000 Genomes super-populations using a chi-square test and pairwise Fst. This template operates on 1000 Genomes data and asks an entirely different question — super-population differentiation at a locus — than the one we scoped. This sprint reports a failed outcome due to a capability mismatch. No data were fetched, no analysis was run, and no figure was produced.
Failed Capability Disclosure: ClinVar Pathogenic vs Benign Variant Frequency at GJB2
Sprint 23, Run 24
Abstract
We scoped the question: For GJB2, do ClinVar-pathogenic variants sit at lower gnomAD population frequency than benign ones? This question requires (1) retrieving ClinVar variants classified as pathogenic or benign for gene GJB2, (2) joining them to gnomAD allele-frequency data, and (3) statistically comparing the allele-frequency distributions of the two pathogenicity classes. The capability gate selected the population_allele_freq reference template, which tests whether a single variant or region differs in allele frequency across 1000 Genomes super-populations using a chi-square test and pairwise Fst. This template operates on 1000 Genomes data and asks an entirely different question — super-population differentiation at a locus — than the one we scoped. This sprint reports a failed outcome due to a capability mismatch. No data were fetched, no analysis was run, and no figure was produced.
Introduction
GJB2 (gap junction protein beta 2, encoding connexin 26) is the most commonly mutated gene in autosomal recessive non-syndromic hearing loss. ClinVar classifies variants as pathogenic, likely pathogenic, benign, or likely benign, while gnomAD provides population-level allele-frequency data. A natural question is whether pathogenic GJB2 variants are rarer (lower allele frequency) in the general population than benign ones — which would be expected if pathogenic variants are subject to purifying selection.
Methods
Scoped Question
For GJB2, do ClinVar-pathogenic variants sit at lower gnomAD population frequency than benign ones?
Required Analysis
The capability gate assigned population_allele_freq, which performs:
- Chi-square test of allele-count homogeneity across five 1000 Genomes super-populations (AFR, AMR, EAS, EUR, SAS) for the lead variant in a region.
- Pairwise Hudson Fst between all super-population pairs for the lead variant.
- Grouped bar chart of per-super-population allele frequency for the lead variant.
This template uses the fetch_1000g.py fetcher (1000 Genomes phase-3 VCF tabix slices) and consumes a --kg CSV of per-super-population allele frequencies.
Capability Mismatch
The population_allele_freq template cannot answer the scoped question for two structural reasons:
- Wrong data source. The template uses 1000 Genomes, not ClinVar or gnomAD. It does not retrieve pathogenicity classifications or gene-specific allele frequencies.
- Wrong statistical question. The template tests whether a single variant's allele frequency varies across five continental populations (a between-population test). The scoped question asks whether variants of different pathogenicity classes differ in allele frequency (a between-category test requiring ClinVar labels and gnomAD frequencies).
No amount of data retrieval or script adaptation can make this template answer the original question without fabricating a fundamentally different analysis — which violates the honesty constraint.
Results
No data were fetched. No analysis was performed. No figure was produced. The pipeline stopped at the scoping stage upon identifying an irreconcilable capability mismatch between the assigned template and the question.
Discussion
A template that joins ClinVar pathogenicity labels to gnomAD allele frequencies and compares them would be needed to answer this question. The capability gate would need to assign such a template for this idea to proceed beyond scoping. In this run, the assigned template (population_allele_freq) cannot serve this purpose, so the sprint correctly stopped at the scoping stage.
Limitations
- This paper contains no empirical findings; it is a capability disclosure only.
- The mismatch is structural (wrong template for the question), not a transient failure.
- No analysis artifacts (stats.json, script, figure, or dataset provenance) were produced during this run.
Provenance
- Sprint ID: 23
- Run ID: 24
- Idea: For GJB2, do ClinVar-pathogenic variants sit at lower gnomAD population frequency than benign ones?
- Assigned template:
population_allele_freq - Outcome:
failed(capability mismatch) - Datasets fetched: None
- Analysis script: None (analysis was not attempted)
- Seeds: None
- No analysis artifacts were produced during this run.
population allele freq
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