Late-onset Familial Amyloidotic Polyneuropathy with Bence Jones Proteinuria and Cardiomyopathy

Familial amyloidotic polyneuropathy is a genetically determined disease characterized by deposition of an anomalous transthyretin. A high index of suspicion is needed for this multisymptomatic and lethal disease to be diagnosed. The patient was a 70-year-old male examined due to hypesthesia in the hands and feet, plus difficulty walking. A neurophysiological study delivered the diagnosis of axonal sensorimotor polyneuropathy. He later developed cardiac symptoms and diarrhea. Urine laboratory analyses revealed a monoclonal spike of light chains (kappa). Biopsies of abdominal fat and bone marrow yielded normal results. The genetic study was compatible with a heterozygous Val30Met-transthyretin mutation. Very few case studies have described an association between familial amyloidotic polyneuropathy and monoclonal gammopathy. We stress that genetic confirmation is important regardless of the type of amyloid deposition revealed by the biopsy.