A table with filters made the user do the work. Rare disease triage is a different task:
which few variants could explain *this* patient's phenotype, and why. The app now answers
that, and lets a reviewer act on the answer.
Domain
- a case is a proband: a VCF plus the HPO terms observed in the patient (samples -> cases)
- HPO's gene-to-phenotype annotations are loaded as reference data (scripts/load-hpo.py)
- each candidate can be shortlisted or dismissed with a reason and a note
Ranking (app/services/triage.py, 21 tests)
- weighted sum of phenotype match, rarity, consequence severity and the model's score,
with every component shown next to the candidate
- rarity and consequence filter; phenotype only ranks, because a real diagnosis can sit in
a gene nobody has annotated yet and filtering on it would hide exactly that case
- ClinVar is deliberately not an input: it appears beside the result as independent
confirmation, so nothing ranks highly merely because ClinVar already said pathogenic
UI
- the funnel is the headline: variants called -> rare -> coding candidates -> phenotype-matched
- ranked candidates with evidence chips, not a grid of everything; filters are demoted
- a variant panel showing the score breakdown, the matched HPO terms, the raw VEP record and
links out to Ensembl/gnomAD/ClinVar, with the decision controls
- a printable case report: phenotype, funnel, shortlisted variants with reasons, provenance
API: /cases with phenotypes, /cases/{id}/candidates (funnel + ranked + weights),
/variants/{id}, /variants/{id}/decision, /cases/{id}/report, /phenotypes for the picker.
Scoring moved under the case and now answers 503 with the reason when no model registry is
reachable, instead of a 500.
Verified end to end on a simulated proband (scripts/make-demo-case.sh: real GIAB HG002
background + one real ClinVar 2-star pathogenic NF2 variant). 13 variants called -> 1 coding
candidate, and the planted variant ranks first at 0.80 on phenotype 1.00, rarity 1.00 and
consequence 1.00, with ClinVar agreeing afterwards.
Tests: api 75, ml 18, loader 16, web 27; ruff, mypy, svelte-check, terraform validate, both
kustomize overlays and the Nextflow stub run all clean.
7.2 KiB
Data: what rarelens actually runs on
Everything below is public, peer-reviewed and consented for open redistribution. No patient data, no data access agreement, nothing that needs an application. These are the references to quote when showing the platform to someone.
Citations were verified against PubMed; each row links its DOI.
The demo slice
make data fetches two real files, chromosome 22 only (roughly 100 MB, minutes rather than hours):
| File | What it is | Role |
|---|---|---|
data/example.vcf.gz |
GIAB HG002 (NA24385) v4.2.1 benchmark calls, GRCh38, chr22 | the sample a scientist annotates |
data/clinvar.chr22.vcf.gz |
ClinVar, GRCh38, chr22 | training labels, and the ClinVar column in the UI |
HG002 is the NIST Genome in a Bottle Ashkenazi son, recruited through the Personal Genome Project, which consents participants to unrestricted public release. It is the reference genome the field benchmarks variant callers against, so it is both realistic and unambiguously shareable.
Datasets
| Dataset | Used for | Access | Terms | Citation |
|---|---|---|---|---|
| ClinVar (GRCh38) | pathogenic/benign labels, ClinVar column | ftp.ncbi.nlm.nih.gov/pub/clinvar/vcf_GRCh38/ |
NCBI public domain | Landrum et al., Nucleic Acids Res 48(D1):D835–D844, 2020. 10.1093/nar/gkz972 |
| Genome in a Bottle HG002 v4.2.1 | the demo sample | ftp-trace.ncbi.nlm.nih.gov/ReferenceSamples/giab/, s3://giab |
open, no use restriction | Zook et al., Nat Biotechnol 37:561–566, 2019. 10.1038/s41587-019-0074-6 |
| gnomAD v4 | allele frequency feature and filter | gs://gcp-public-data--gnomad, s3://gnomad-public-us-east-1 |
free use, no restriction | Chen et al., Nature 625:92–100, 2024. 10.1038/s41586-023-06045-0; Karczewski et al., Nature 581:434–443, 2020. 10.1038/s41586-020-2308-7 |
| 1000 Genomes 30x | optional cohort/trio data | EBI FTP, s3://1000genomes |
fully open, no access restriction | Byrska-Bishop et al., Cell 185(18):3426–3440.e19, 2022. 10.1016/j.cell.2022.08.004 |
| MANE Select | one transcript per gene, if transcript choice ever matters | Ensembl/RefSeq | open | Morales et al., Nature 604:310–315, 2022. 10.1038/s41586-022-04558-8 |
| Human Phenotype Ontology gene-to-phenotype | what the phenotype half of the ranking matches against (make hpo) |
purl.obolibrary.org/obo/hp/hpoa/genes_to_phenotype.txt |
free to use with attribution | Gargano et al., Nucleic Acids Res 52(D1):D1333–D1346, 2024. 10.1093/nar/gkad1005 |
Tools and scores
| Tool | Role | Terms | Citation |
|---|---|---|---|
| Ensembl VEP 113 | annotation (pipeline/modules/vep.nf) |
Apache 2.0 | McLaren et al., Genome Biol 17:122, 2016. 10.1186/s13059-016-0974-4 |
| CADD | cadd_phred feature |
free for non-commercial use; commercial licence required | Rentzsch et al., Nucleic Acids Res 47(D1):D886–D894, 2019. 10.1093/nar/gky1016; Schubach et al., Nucleic Acids Res 52(D1), 2024. 10.1093/nar/gkad989 |
| AlphaMissense | am_pathogenicity feature |
predictions moved to CC BY 4.0 in March 2024 (originally CC BY-NC-SA) | Cheng et al., Science 381:eadg7492, 2023. 10.1126/science.adg7492 |
Neither score is required: rarelens_ml.features treats a missing CADD or AlphaMissense value as
NaN and LightGBM handles it, so the pipeline runs without the plugin data.
The simulated proband
make demo-case builds data/proband-simulated.vcf.gz: real GIAB HG002 variants as background
plus one real ClinVar 2-star pathogenic variant in a disease gene (NF2 by default, giving
neurofibromatosis type 2). Spiking a known variant into a public genome is how phenotype-driven
triage tools are benchmarked, every input is public, and the file's header says SIMULATED. It is
not a patient, and no part of it is invented: both the background and the planted variant are real
published records.
The point of it is that the case has a right answer, so the ranking can be checked rather than admired. Give the case the phenotype of the planted disease and the planted variant should rank first — on phenotype, rarity and consequence, with ClinVar agreeing only afterwards.
Caveat when running without a VEP cache. VEP_DATABASE=true queries Ensembl's public database
instead of the 25 GB cache. It returns no gnomAD frequencies, so every variant looks absent from
gnomAD and the rarity term stops discriminating. Fine for showing the mechanics; use the cache for
anything you would quote.
Evaluating the model honestly
The model trains on ClinVar labels and is scored on ClinVar-labelled variants, which is exactly where published benchmarks go wrong. What to do about it:
- Never let the label into the features.
CLIN_SIGis excluded by construction;clinvar_sigis stored for display only (rarelens_ml/features.pylists the five feature columns). - Split by gene, not by variant. Random splits put variants from the same gene on both sides, and a model can then score a gene rather than a variant. Grimm et al. showed this inflates reported accuracy for exactly this class of tool: Hum Mutat 36:513–523, 2015. 10.1002/humu.22768
- Prefer a time-based holdout. Train on an older ClinVar release (monthly archives live under
vcf_GRCh38/archive_2.0/) and test only on variants classified after that date. This is the closest thing to a prospective evaluation available without new patients. - Filter labels by review status. ClinVar's
CLNREVSTATmarks how much evidence backs a classification; two-star and above ("multiple submitters, no conflicts") is the usual bar. Known gap: VEP'sCLIN_SIGdoes not carry review status, so this needs ClinVar annotated as a custom field before it can be enforced. - Report against published baselines on the same rows. CADD PHRED and AlphaMissense are already columns in the variant table, so AUROC and AUPRC for the model next to those two, with the variant count, is a fair comparison rather than a number with nothing to beat.
- Report AUPRC, not just AUROC. Pathogenic variants are the minority class; AUROC flatters.
What must not be claimed
ACMG/AMP treats computational predictions as supporting evidence only, never sufficient on their own for classifying a variant (Richards et al., Genet Med 17:405–424, 2015. 10.1038/gim.2015.30). rarelens is a learning platform on public data: it makes no diagnostic claim, and the UI shows a score next to the evidence rather than a verdict. For what a real diagnostic pipeline looks like end to end, see the 100,000 Genomes Project rare-disease pilot: Smedley et al., N Engl J Med 385:1868–1880, 2021. 10.1056/NEJMoa2035790