splicevariant

A splice variant, in genetics, is a transcript variant produced from the same gene by alternative splicing of pre-mRNA. Through selective use of splice junctions, a single gene can give rise to multiple mRNA products, which in turn can code for distinct protein isoforms or, in some cases, noncoding RNAs. Splice variants contribute to genetic and functional diversity in eukaryotes.

Common modes of alternative splicing include exon skipping, alternative 5' or 3' splice sites, intron retention, and mutually exclusive exons. In addition, different promoters or polyadenylation sites can alter transcript ends, producing variant transcripts with different 5' or 3' untranslated regions and, sometimes, different coding sequences. Some variants are tissue- or development-specific.

Splicing is governed by cis-regulatory elements in the RNA sequence and trans-acting splicing factors. Detection and annotation rely on RNA sequencing, RT-PCR, and genome annotations in resources such as Ensembl and RefSeq. Thousands of splice variants have been cataloged for many genes.

Functional consequences vary by variant. Some isoforms differ in catalytic domains, localization signals, or interaction motifs, affecting protein function. Others regulate gene expression through alternative UTRs or noncoding transcripts. Aberrant splicing, involving unintended splice variants, is associated with numerous diseases, including cancer and inherited disorders, and is an area of therapeutic interest.