The Ile122 transthyretin variant associated with restrictive cardiomyopathy has been described in African-Americans and estimated to be present in approximately 4% of the Black population. We report the first American-Caucasian family with cardiomyopathy due to the TTR Ile122 mutation. The high prevalence of this mutation in the Black population and the discovery that it may cause disease in other ethnic populations highlights the importance of considering this autosomal dominant systemic amyloidosis in all individuals with restrictive cardiomyopathy. Inadequate diagnosis combined with inappropriate treatment may have a significant impact on morbidity and mortality.