Presence of a plasma transthyretin (prealbumin) variant in familial amyloidotic polyneuropathy in a kindred of Greek origin.

Human plasma transthyretin (TTR, a protein formerly called prealbumin) is known to be associated with familial amyloidotic polyneuropathy (FAP) of autosomal inheritance. A variant TTR with a methionine-for-valine substitution at position 30 has been described as the major protein component of amyloid in Portuguese and Japanese patients with FAP and in patients of Swedish ancestry with FAP. In these patients, TTR(Met30) also circulates in relatively low concentration in the plasma. TTR variants having substitutions in other positions have also been reported in a patient of Jewish origin with FAP. We now report studies on TTR from an FAP kindred of Greek ancestry. By peptide mapping analysis, plasma TTR from the propositus was compared with TTR from a Portuguese patient with FAP. TTR(Met30) was found to circulate in the blood plasma of the Greek propositus. By use of a recently developed immunoblotting technique, this variant TTR was also detected in some of the relatives of the propositus. Future studies of this mutant gene among ethnically different FAP populations might contribute to an understanding of selection and persistence of the mutation.