Mutations Can Also Occur Within the Regulatory Regions of Genes

Multiple Choice

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?

A) promoter
B) polyadenylation
C) splice site
D) triplet-repeat expansion
E) frameshift