Question

In myotonic dystrophy type one, there is an expansion of the cytosine-thymine-guanine (ctg) triplet repeat in the dmpk gene. this leads to loss of muscular function where often times the muscles contract, but do not relax. this can lead to cataracts, cardiac conduction problems, and intellectual disabilities.

what is a possible cause and mechanism of this trinucleotide repeat disorder?

Answer 1

Myotonic dystrophy type one is a form of muscular dystrophy caused by the expansion of the CTG triplet repeat in the DMPK gene, affecting muscle relaxation and leading to various health issues.

Step-by-step explanation:

In myotonic dystrophy type one, a type of muscular dystrophy, a mutation results in an expansion of the cytosine-thymine-guanine (CTG) triplet repeat within the DMPK gene. This genetic alteration leads to a dysfunction in muscle relaxation following contraction and can cause a range of health issues including cataracts, cardiac conduction defects, and intellectual disabilities.

The expansion of the CTG triplet repeat interferes with the normal function of the gene, leading to a harmful gain of function or a toxic RNA effect that disrupts normal cellular processes. Over time, the altered protein translation and accumulation of repeat-containing RNA transcripts contribute to the progressive muscle wasting and weakening that characterizes this disorder.