This means that the defective gene responsible for the disorder is located on an autosome (chromosome 18 is an autosome), and only one copy of the defective gene is sufficient to cause the disorder, when inherited from a parent who has the disorder. Diagnosis
Clinical suspicion for FAP is raised on the basis of a family history of neuropathy and physical exam showing signs of neuropathy. Diagnosis can be made using genetic testing to identify mutations in the TTR gene, but may include other corroborative investigation. Nerve conduction testing typically shows an axonal polyneuropathy, with sensory involvement greater than motor. Superimposed mononeuropathies may also be evident, such as a median mononeuropathy at the wrist (carpal tunnel syndrome). Electromyography (EMG) may show evidence of chronic denervation and reinnervation. Autonomic testing, including quantitative sweat testing, can reveal involvement of the autonomic nervous system. Occasionally, biopsy of skin, nerve, or muscle may be performed, which can show signs of denervation and amyloid deposition with response to anti-TTR antibodies. Additional testing should be performed to identify involvement of the heart or kidneys.Sudomotor function through electrochemical skin conductance may provide a measure of subclinical autonomic involvement. Treatments
The medication tafamidis has been approved for the treatment of transthyretin familial amyloid polyneuropathy in Europe. Studies have found that it delays neurological problems when started early. The US Food and Drug Administrations Peripheral and Central Nervous System Drugs Advisory Committee rejected the drug in June 2012, in a 13-4 vote.
Epidemiology
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. ll the analysed Portuguese families presented the same haplotype (haplotype I) associated with the Met 30 mutation. In northern Sweden, more specifically  Skellefteå (it is locally called "Skelleftesjukan", the Skellefteå disease), 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. References
External links

GeneReviews/NIH/NCBI/UW entry on Familial Transthyretin Amyloidosis