• amyloidosis
• gelsolin
• Meretoja disease
• neuropathy.

A 60-year-old Brazilian man gave a 20-year history of progressive bilateral facial weakness. He was known to have lattice corneal dystrophy. His father, two paternal uncles and a son had similar neurological problems. His father was born in Portugal and his paternal grandmother was born in Finland. On examination, there was severe bilateral facial weakness (figure 1). Neurophysiology studies found bilateral axonal facial neuropathy but neuroimaging was normal. Genetic analysis found a heterozygous pathogenic mutation c.654G>A (p.Asp187Asn) in the GSN gene, confirming a diagnosis of Finnish type amyloidosis.

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Figure 1

Examination findings in Finnish type amyloidosis. (A–C) Bilateral severe facial weakness, which is slightly asymmetric and involves both the upper and lower face.

Finnish type hereditary amyloidosis (also known as familial amyloidotic polyneuropathy type IV, or Meretoja disease; OMIM #105120) is an autosomal dominant hereditary neuropathy caused by mutations in the GSN gene (9q33.2). It is characterised by the triad of lattice corneal dystrophy type II, cutis laxa and progressive bilateral facial paralysis.1 It is more common among Finnish people, and most cases have the pathogenic mutation found in our patient. Patients may have cardiomyopathy, chronic renal failure, nephrotic syndrome, gastrointestinal complaints and variable autonomic disturbances, although these are less common than in TTR-related familial amyloidotic polyneuropathy.1 Although very rare, Finnish type amyloidosis should be considered in patients presenting with slowly progressive bilateral facial weakness, where the differential diagnosis would include Lyme disease, sarcoidosis, Melkersson-Rosenthal syndrome and neurolymphomatosis.1 2