Being an autosomal dominant genetically transmitted disease, FAP is transmitted from parents to children, one mutated gene being enough (in only one of the alleles), in any of the progenitors, for the disease to be passed on.
FAP is characterized by the systemic deposition of amyloidogenic variants of the transthyretin protein, especially in the peripheral nervous system, causing a progressive sensory and motorial polyneuropathy.
Usually manifesting itself between 20 and 40 years of age, it is characterized by pain, paresthesia, muscular weakness and autonomic dysfunction. In its terminal state, the kidneys and the heart are affected. In the absence of a liver transplant, FAP is invariably fatal.
This disease is endemic in Portuguese locations Póvoa de Varzim and Vila do Conde (Caxinas), with more than 1000 affected people, coming from about 500 families, where 70% of the people develop the illness. It was brought by Vikings from Scandinavia during the Middle Age. In northern Sweden, more specifically Piteå, Skellefteå and Umeå, 1.5% of the population has the mutated gene. There are many other populations in the world who exhibit the illness after having developed it independently.
Andrade C., A peculiar form of peripheral neuropathy. Familial atypical generalized amyloidosis with special involvement of the peripheral nerves, Brain 1952; 75:408-27.