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.
The bicarbonate (HCO3−) exits at the basal portion of the cell via sodium (Na+) symport and chloride (Cl−) antiport and re-enters circulation, where it may accept a proton if blood pH decreases, thus acting as a weak, basic buffer. The remaining H+ left over from the intracellular production of carbonic acid (H2CO3) exits the apical (urinary lumen) portion of the cell by Na+ antiport, acidifying the urine. There, it may join with another bicarbonate (HCO3−) that dissociated from its H+ in the lumen of the urinary space only after exiting the proximal convoluted kidney cells/glomerulus as carbonic acid (H2CO3) because bicarbonate (HCO3−) itself can not diffuse across the cell membrane in its polar state. This will replenish carbonic acid (H2CO3) so that it then may be reabsorbed into the cell as itself or CO2 and H2O (produced via a luminal carbonic anhydrase). As a result of this whole process, there is a greater net balance of H+ in the urinary lumen than bicarbonate (HCO3−), and so this space is more acidic than physiologic pH. Thus, there is an increased likelihood that any bicarbonate (HCO3−) that was left over in the lumen diffuses back into the cell as carbonic acid, CO2, or H2O. In short, under normal conditions, the net effect of carbonic anhydrase in the urinary lumen and cells of the proximal convoluted tubule is to acidify the urine and transport bicarbonate (HCO3−) into the body.