The transthyretin (TTR) Ile 122 variant is associated with cardiac amyloidosis in individuals of African descent. To determine the prevalence of the allele encoding TTR Ile 122 in African-Americans, we have used PCR and restriction analysis to test DNA from African-Americans from various geographic areas, and found an allele frequency of 66/3376 (0.020), which is higher than the value we previously reported in a much smaller pilot study. Our data indicate that this TTR variant is present at equal frequency in African-Americans throughout the U.S., and suggest that this mutation may be a common, often unrecognized cause of cardiac disease in African-Americans.

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A 65-year-old man had an 18-month history of slowly progressive swelling and discoloration of both ears, fatigue, night sweats, weight loss, occipital headaches, and photophobia. On examination, his ears were swollen and purplish and had several small cysts that were neither warm nor tender. The skin of his nose, cheeks, upper lip, and chin was also thickened and discolored (Panel A). He had diffuse peripheral lymphadenopathy. Funduscopy demonstrated tortuous arterioles, distended prominent veins bilaterally with diminished pulsations, and retinal hemorrhages. Serum immunoelectrophoresis revealed a monoclonal IgM spike with an IgM level of 7.7 g per liter and a relative viscosity of 18.8. The patient underwent plasmapheresis. Biopsy of the left ear revealed diffuse dermal lymphoplasmacytic infiltrates (Panel B; hematoxylin and eosin, ¬100), with numerous plasma cells showing intranuclear inclusions of immunoglobulin, or Dutcher bodies (arrows in Panel C; hematoxylin and eosin, ¬500). Examination of a bone marrow aspirate and a bone marrow-biopsy specimen showed dense infiltration with lymphoplasmacytic cells expressing monotypic IgM lambda light chains, thus confirming the diagnosis of Waldenström's macroglobulinemia. The patient's symptoms improved dramatically with plasmapheresis and the institution of chemotherapy with fludarabine, and the swelling of his ears resolved.

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