A new mutation causing familial amyloidotic polyneuropathy.

The DNA from an individual with familial amyloidotic polyneuropathy was examined. It did not possess any of the mutations which have previously been associated with familial amyloidotic polyneuropathy. However, a novel 7.0 kb Sph I restriction fragment was discovered, and the mutation creating it was localized to exon 3 of the transthyretin gene. This mutation was inherited from a parent, and may result in an amino acid substitution for glu89, his90 or ala91. The patient's transthyretin has a lower pI than normal transthyretin.