A novel type of familial transthyretin amyloidosis, ATTR Asn124Ser, with co-localization of κ light chains

A 68-year-old Italian woman who had a clinical history of thyroidectomy in 2002 presented with slowly progressing renal insuffiency and non-nephrotic proteinurea in 2004. A renal biopsy showed the occurrence of amyloid; the thyroid biopsy previously taken also revealed amyloid infiltration. Other amyloid-containing tissues included bone marrow and heart. The plasma cell level in the bone marrow was found to be less than 5% and both serum and urine samples were positive for a monoclonal κ light chain band. DNA analysis unexpectedly revealed the presence of a novel transthyretin (TTR) mutation, ATTR Asn124Ser. Histologically, amyloid deposits in the thyroid had a homogeneous appearance with moderate Congophilia. In immunohistochemistry, a κ light chain antiserum showed positive immunoreactivity with amyloid deposits in the thyroid. Furthermore, a TTR antiserum, anti-TTR50-127, also recognized a number of amyloid deposits stained positive with the κ light chain antiserum. Overall, the κ light chain antiserum...