The most frequent istransthyretin (TTR), a protein that is synthesized in the liver, choroid plexus andretina, and that acts in the transport of thyroxine (T4) and retinol-binding proteinin the blood.1 The TTR gene islocated on chromosome 18q12.1.2 Thebest described, most prevalent mutation is Val30Met (a methionine substitution forvaline at position 30), which predominantly affects patients from Japan, Portugal,Sweden and Brazil.3 Amyloidosis symptoms appear in the third to fifthdecades of life, including progressive polyneuropathy, postural hypotension, andmild myocardial infiltration. The gene discussed is TTR; the disease is polyneuropathy.