What is an FMR1 gene mutation?

A mutation is any change in a gene. Some mutations don’t cause any problems and we don’t know about them (unless found in the laboratory). Mutations in the FMR1 gene involve an abnormal expansion of the DNA in the “promoter” area of the gene. Often a mutation causes decreased or absent protein production. In individuals with a “full mutation,” their FMR1 gene is shut down and they don’t make enough or any FMRP (Fragile X Protein). 

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