Intronic Variant Quick Reference

The Intronic Variant Quick Reference (IVQR) is a visual depiction of common nucleotides in intronic regions and their numbering directions. Use this tool to learn the common intronic nucleotide designations and their organization within a gene to aid in your variant interpretation activities.

Includes variant nomenclature definitions for splice donor variant, splice acceptor variant, deep intronic variant, 5 prime (5′) UTR variant, 3 prime (3′) UTR variant, and IVS nomenclature. 

Concepts covered:

• Splice donor site 
• Splice acceptor site
• Intronic nomenclature
• Intronic nucleotide numbering
• Intronic base numbering
• Splice variant nomenclature
• Splice variant numbering 
• Which nucleotides are at the splice donor site
• Which nucleotides are at the splice acceptor site
• UTR nomenclature 
• 3 prime UTR nomenclature (3′)
• 5 prime UTR nomenclature (5′)
• HGVS intronic nomenclature
• HGVS intronic numbering
• HGVS intronic nucleotides