ABSTRACT
Hereditary transthyretin (TTR) myloidosis is associated with greater than 80 different mutations in transthyretin. While the most common type of TTR amyloidosis in the world (Val30Met) is found in large pedigrees in Northern Portugal, Northern Sweden, Japan, and smaller families in United States, Europe, and Australia, one particular TTR mutation (Val122Ile) is found predominantly in Americans of African descent. This mutation causes late-onset restrictive cardiomyopathy (after age 60). The chapter explains the gene frequency in newborns in a mid-American city (Indianapolis, Indiana). In a population selected only by ethnicity and birth in an urban community the finding of 3 percent incidence of the TTR Val122Ile mutation associated with late-onset cardiac amyloidosis is similar to previous reports of studies on preselected DNA samples, but lower than the 3.9 percent found in one study. The amyloidosis caused by this mutation is often clinically mistaken for other types of cardiac disease in the African-American population.
