A case of familial amyloid polyneuropathy homozygous for the transthyretinVal30Met gene with motor-dominant sensorimotor polyneuropathy and unusual sural nerve pathological findings

Objective: To report a case of familial amyloid polyneuropathy homozygous f or the amyloidogenic transthyretin (ATTR) Val30Met gene with motor-dominant sensorimotor polyneuropathy and unusual sural nerve pathological findings. Methods: Mass spectrometry analysis and polymerase chain reaction-restricti ng fragment length polymorphism were performed. A right sural nerve biopsy specimen was obtained for histological investigation. Setting: Academic medical center. Results: A 56-year-old japanese man living in a local town (Nakajima, Japan ) in Ishikawa Prefecture, a nonendemic area of type I familial amyloidotic polyneuropathy, had vitreous amyloidosis, motor-dominant sensorimotor polyn europathy, erectile dysfunction, and urinary incontinence. He had neither o rthostatic hypotension nor indolent diarrhea. Restriction enzyme analysis w ith EcoT22 I of amplified DNA and mass spectrometry analysis revealed homoz ygosity for ATTR Val30Met. Of 8 family members, 5 were evaluated and found to be heterozygous for ATTR Val30Met; a family history found no relative wi th the similar neurologic disorders. The sural nerve biopsy specimen showed focal edema and an amyloid deposit in the subperineural tissue, associated with moderate loss of myelinated and unmyelinated fibers. Conclusions: In addition to the findings characteristic of homozygosity for ATTR Val30Met such as vitreous amyloidosis and relatively less autonomic i nvolvements, this case had the unique findings of motor-dominant sensorimot or polyneuropathy and unusual sural nerve biopsy specimen results.