What type of mutation is seen in Becker Muscular Dystrophy (BMD)?

Becker Muscular Dystrophy (BMD) is primarily associated with mutations in the dystrophin gene, which is critical for maintaining the structural integrity of muscle fibers. The mutations leading to BMD are typically in-frame mutations, which result in a partially functional dystrophin protein.

In-frame mutations occur when deletions or insertions of nucleotides in a gene are in multiples of three. This type of mutation preserves the reading frame, allowing the synthesis of a truncated but still somewhat functional protein. In the case of BMD, the mutations usually lead to the loss of some exons from the dystrophin gene, resulting in a shorter protein than normal, but it retains enough functionality to allow for key physiological functions.

This contrasts with other mutations such as frameshift mutations, which shift the reading frame and usually lead to a completely nonfunctional protein, or nonsense mutations, which introduce a premature stop codon and also result in nonfunctional proteins. Point mutations, while they can be significant, do not typically account for the characteristic mutations observed in BMD. Thus, the nature of the mutation in Becker Muscular Dystrophy aligns with an in-frame mutation leading to the production of a partially functional dystrophin protein.