What codon is involved in abnormal splicing that results in its premature occurrence?

The stop codon is correct in the context of abnormal splicing leading to premature termination of translation. In normal protein synthesis, the stop codon indicates the end of the coding sequence, signaling the ribosome to halt translation and release the assembled polypeptide chain.

In cases of abnormal splicing, mutations can occur that introduce or expose a stop codon within the coding sequence prematurely. This can happen due to incorrect removal of introns or misidentification of exons, leading to a truncated protein that often lacks essential functional regions. This phenomenon is critical because such truncated proteins can result in loss of function or cause disease due to unregulated protein production leading to toxic effects.

The start codon, exon codon, and intron codon don't play the same role as stop codons in this context. The start codon is primarily involved in the initiation of translation, while exons and introns refer to the segments of pre-mRNA and do not directly account for the premature termination during splicing.