Hereditary transthyretin amyloidosis: a case report

BACKGROUND: Hereditary transthyretin amyloidosis is an uncommon multisystem disorder caused by mutation of the transthyretin protein, leading to peripheral neuropathy often with autonomic features, cardiomyopathy, or a mixed phenotype. Multiple other organ systems can be involved with ophthalmologic, renal, hematologic, gastrointestinal, and/or genitourinary symptoms and signs. This often results in assessments by multiple specialists and significant delays before the diagnosis is recognized. With the recent advent of potentially lifesaving therapies, early diagnosis has become even more important. Our case highlights the protean aspects of this disease as well as the difficulty of making this diagnosis, especially in the absence of a clear family history. CASE PRESENTATION: We report the case of a 64-year-old man of East-Asian descent who presented with diarrhea, mild anemia, and symptoms of peripheral neuropathy. Numerous investigations and specialist evaluations did not identify a cause. Progression of neurologic symptoms and the development of new hematologic abnormalities ultimately led to consideration of hereditary transthyretin amyloidosis. The diagnosis was confirmed after re-examining previously acquired gastrointestinal biopsies and pursuing genetic testing, which confirmed a pathogenic mutation in the transthyretin gene. He was subsequently started on a novel gene-silencing therapy. On clinical follow-up 8 months after initiation of therapy, the patient described stabilization of previously progressive numbness, weakness, and weight loss with an unchanged neurologic examination and stable repeat electrophysiologic testing. CONCLUSIONS: Hereditary transthyretin amyloidosis is a challenging disease to recognize in early stages owing to its multisystem and nonspecific manifestations. Recent approval of novel therapies highlights the importance of early diagnosis before irreversible organ damage occurs.