Familial amyloid cardiomyopathy masquerading as chronic Guillain-Barre syndrome: things are not always what they seem.

Familial amyloid cardiomyopathy is a challenging condition that mimics many other diseases, particularly in patients with pronounced neurological presentations and unexplained or equivocal cardiac abnormalities. In this case, a 57-year-old man was admitted for outpatient cardiological evaluation of progressive right heart failure and limb paraesthesias. The patient presented with hypertension, chronic Guillain-Barre syndrome, and sick sinus syndrome. Transthoracic echocardiograms showed a thickened ventricular wall and enlarged atrium. Tissue Doppler showed a restrictive filling pattern. Transthyretin (TTR)-associated amyloidosis, which was revealed by abdominal fat-pad biopsy and DNA analysis, explained the concurrence of independent pathological features, including neuropathy and cardiac involvement. Genetic testing identified a G > T mutation in exon 4 of the transthyretin (TTR) gene. This mutation resulted in the alanine-to-serine substitution at amino acid position 117. Moreover, genetic testing confirmed that the patient's asymptomatic son carried the same amyloidogenic TTR mutation. Given these findings, the diagnosis of familial amyloid cardiomyopathy, which was misdiagnosed as chronic Guillain-Barre syndrome, was proposed.