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