Some genes may undergo alternative splicing, a process that results in the generation of different protein variants from the same genetic sequence by altering the pattern of intron and exon elements joined by splicing to produce mRNA. The instructions for these alternative mRNA products are contained within the gene transcripts. For some genes, different transcripts are expressed in different tissues at different stages in development.
First, Invitae scientists review the available literature to find clinically relevant variants in a gene. Then, they compare the discovered variants with the available transcripts for each gene and select the transcript that captures the majority of clinically reported variants. To ensure that previously described clinically relevant variants aren't missed, we will report on several transcripts when there isn't a single transcript that captures all reported variants because of alternative splicing.
For more information on truncations in the last exon, see “Why are termination codons in the last exon VUS?”