**Question:** Base substitution mutations can have the following molecular consequence except

A. Mismatch repair
B. Splicing
C. Point mutation
D. Chromosomal translocation

**Core Concept:** Base substitution mutations are errors that occur during DNA replication, leading to changes in the genetic code. These mutations can result in point mutations, which involve a single nucleotide change. Mismatch repair is a mechanism that corrects errors in DNA replication. Splicing is the process of joining intron and exon sequences during mRNA processing. Chromosomal translocation involves the joining of two different chromosomes, which is not directly related to base substitution mutations.

**Why the Correct Answer is Right:** Chromosomal translocation is a type of genetic abnormality that occurs at the chromosomal level, involving the fusion of two non-adjacent chromosomes. Unlike base substitution mutations, translocations involve the rearrangement of chromosomes, rather than altering a single nucleotide. As a result, the molecular consequence of chromosomal translocation is different from those listed in the question.

**Why Each Wrong Option is Incorrect:**

A. Mismatch repair is a cellular process that corrects errors, including base substitution mutations. In this case, mismatch repair would not be considered an exception to the molecular consequences of base substitution mutations.

B. Splicing is the process of joining intron and exon sequences during mRNA processing, which occurs after DNA replication and transcription. Although splicing is a relevant post-transcriptional process, it does not directly relate to the molecular consequences of base substitution mutations.

**Clinical Pearl:** Understanding the molecular consequences of different genetic abnormalities is crucial for interpreting clinical findings and making accurate diagnoses. This knowledge can help guide treatment decisions and provide insight into the underlying causes of genetic disorders and diseases.