Final answer:
Approximately 25% of point mutations affecting genetic diseases impact splicing of pre-mRNA. Splicing errors can be caused by mutations in the spliceosome machinery or recognition sequences, leading to abnormal protein variants or protein loss.
Step-by-step explanation:
Approximately 25% of all point mutations that cause genetic diseases affect splicing of pre-mRNA. Errors in splicing can occur due to different kinds of mutations, such as mutations in the spliceosome machinery or mutations in the recognition sequences at the 5' and 3' end of the introns.
These mutations can lead to splicing errors and result in different outcomes, such as the creation of abnormal protein variants or the loss of the original protein.