Mutations can also occur within the regulatory regions of genes. Fragile X is an example of a disorder caused by one such mutation that increases the length of the long arm of the X chromosome and ultimately decreases mRNA stability. Which type of regulatory mutation causes Fragile X?

Question

Quizplus · Accepted Answer

Fragile X is caused by a triplet-repeat expansion mutation in the FMR1 gene, located on the X chromosome. This mutation leads to an abnormal increase in the number of CGG repeats in the 5' untranslated region of the FMR1 mRNA, resulting in decreased mRNA stability and a functional loss of the FMR1 protein. This type of regulatory mutation affects gene expression by altering the stability and translation of the mRNA rather than the structure of the resulting protein.

Mutations Can Also Occur Within the Regulatory Regions of Genes