FFI is one of the two genetic or inherited Creutzfeldt-Jakob diseases. It is extremely rare, affecting only about 40 families worldwide, primarily of, but not limited to, Italian descent. The disease is autosomal dominant, meaning that a person needs to get the abnormal gene from only one parent in order to inherit the disease. Individuals with this rare disorder have inherited a Prnp gene (prion protein) that has the substitution of aspartic acid by asparagine at codon 178 accompanied with a methionine at position 129. The Prnp gene is the gene that provides instructions for making prion protein (PrPC). This gene is located on the short arm of chromosome 20 at position p13.
