Mutations in the serum protein transthyretin (TTR) cause amyloidosis involving the peripheral nerves, heart, and other organs. In Ashkenazic Jews, the only TTR variant described to date has been TTR Ile 33. We have studied DNA from another Ashkenazic Jewish kindred with familial amyloidotic polyneuropathy. Single-strand conformation polymorphism analysis, DNA sequencing, and restriction analysis indicated that this kindred has the TTR Pro 36 variant, previously described only in a Greek kindred.