In the β/A4 protein of Alzheimer's disease, on chromosome 21, three mutations at the same locus have been described (Val 717 lle, Val 171 Phe, and Val 171 Gly). The heterogeneity of the disease was indicated in individuals with mutations involving chromosomes 19 and 14 as well. β Protein has also been demonstrated in the rimmed vacuoles of inclusion-body myositis. Therapeutic advances include orthotopic liver transplantation to remove the site of synthesis of the mutant transthyretin molecule. Clinical manifestations of the various forms of amyloidosis involve virtually every system in the body; the breadth of the curious series of proteins called amyloid has been extended considerably in the past year.