The present invention generally relates to determining the clinical significance of a variant nucleic acid sequence. The invention can involve sequencing a nucleic acid to generate at least one sequence read, identifying a variant sequence within the sequence read, determining the equivalent insertion/deletion region (EIR) of the variant sequence, identifying a functional region including at least a portion of the EIR, and associating the EIR with the identified functional region, thereby to determine the clinical significance of the variant.