Version Compatibility
Reference examples tested with: SnpEff 5.2+, pandas 2.2+
Before using code patterns, verify installed versions match. If versions differ:
- Python:
pip show <package> then help(module.function) to check signatures
If code throws ImportError, AttributeError, or TypeError, introspect the installed
package and adapt the example to match the actual API rather than retrying.
MyVariant.info Queries
"Annotate my variants from multiple databases at once" → Query the myvariant.info aggregation API to retrieve ClinVar, gnomAD, dbSNP, COSMIC, and other annotations in a single request per variant.
- Python:
myvariant.MyVariantInfo().getvariants(ids, fields='clinvar,gnomad,dbnsfp')
Required Imports
import myvariant
Initialize Client
mv = myvariant.MyVariantInfo()
Query Single Variant
Goal: Retrieve aggregated annotations for a single variant from multiple databases in one request.
Approach: Query myvariant.info by HGVS notation or rsID, which returns ClinVar, gnomAD, dbSNP, COSMIC, and CADD data.
# Query by HGVS notation (recommended)
result = mv.getvariant('chr7:g.140453136A>T')
# Query by rsID
result = mv.getvariant('rs121913527')
# Query by gene and protein change
result = mv.getvariant('BRAF:p.V600E')
Query Multiple Variants
Goal: Batch-query up to 1000 variants in a single API call with field selection for efficiency.
Approach: Pass a list of variant identifiers to getvariants() with specific field filters to minimize response size.
variants = [
'chr7:g.140453136A>T',
'chr17:g.7577120C>T',
'rs121913527'
]
# Batch query (up to 1000 variants per request)
results = mv.getvariants(variants)
# With specific fields
results = mv.getvariants(
variants,
fields=['clinvar', 'gnomad_exome', 'dbsnp']
)
Search Variants
Goal: Search for variants by gene, clinical significance, or genomic region using query syntax.
Approach: Use Lucene-style query strings with mv.query() to filter by gene symbol, ClinVar fields, or coordinate ranges.
# Search by gene
results = mv.query('clinvar.gene.symbol:BRCA1', size=100)
# Search pathogenic variants in gene
results = mv.query(
'clinvar.gene.symbol:BRCA1 AND clinvar.clinical_significance:Pathogenic',
size=100
)
# Search by genomic region
results = mv.query('chr7:140400000-140500000')
Available Fields
Common field paths for annotations:
| Field | Description |
|---|
clinvar | ClinVar annotations |
gnomad_exome | gnomAD exome frequencies |
gnomad_genome | gnomAD genome frequencies |
dbsnp | dbSNP annotations |
cosmic | COSMIC cancer mutations |
cadd | CADD deleteriousness scores |
dbnsfp | dbNSFP functional predictions |
snpeff | SnpEff annotations |
Extract Specific Annotations
Goal: Extract ClinVar classification, gnomAD frequency, and CADD score from a variant result.
Approach: Navigate the nested JSON response using dictionary access to reach specific annotation fields.
result = mv.getvariant('chr7:g.140453136A>T')
# ClinVar classification
clinvar_sig = result.get('clinvar', {}).get('clinical_significance')
# gnomAD allele frequency
gnomad_af = result.get('gnomad_exome', {}).get('af', {}).get('af')
# CADD score
cadd_phred = result.get('cadd', {}).get('phred')
Batch Processing with DataFrame
Goal: Convert batch variant query results into a structured pandas DataFrame for downstream analysis.
Approach: Query multiple rsIDs with selected fields, extract key annotations per variant, and assemble into a DataFrame.
import pandas as pd
variants = ['rs121913527', 'rs1800566', 'rs104894155']
results = mv.getvariants(variants, fields=['clinvar', 'gnomad_exome'])
records = []
for r in results:
records.append({
'query': r.get('query'),
'clinvar_sig': r.get('clinvar', {}).get('clinical_significance'),
'gnomad_af': r.get('gnomad_exome', {}).get('af', {}).get('af')
})
df = pd.DataFrame(records)
Rate Limiting
Goal: Handle large variant sets exceeding the 1000-variant-per-request API limit.
Approach: Split variants into chunks and query sequentially, relying on myvariant's built-in rate limiting.
# myvariant handles rate limiting automatically
# For large batches, use chunks
def batch_query(variants, chunk_size=1000):
all_results = []
for i in range(0, len(variants), chunk_size):
chunk = variants[i:i + chunk_size]
results = mv.getvariants(chunk)
all_results.extend(results)
return all_results
Related Skills
- clinvar-lookup - Detailed ClinVar queries
- gnomad-frequencies - gnomAD-specific frequency queries
- dbsnp-queries - dbSNP rsID lookups