PharmGKB Get Variant Annotations

Get variant-level literature annotations from PharmGKB/ClinPGx, filtered by gene or chemical PharmGKB Accession ID. Provide gene_id (e.g., 'PA126' for CYP2C9) OR chemical_id (e.g., 'PA451906' for warfarin). Each annotation gives allele/genotype, phenotype category, drug context, significance, and source literature. Results are capped by 'limit'. Keyless. Resolve gene/drug names to PA IDs first via PharmGKB_search_genes / PharmGKB_search_drugs.