Hereditary transthyretin amyloidosis with hydrocephalus at 27 years old: A case report

Hereditary transthyretin amyloidosis is autosomal dominant and results from mutations in the transthyretin gene. The Val30Met variant is the most common genetic mutation, although mutations vary within populations. More than 150 mutations in transthyretin have been reported; however, the Leu111Glu (p. Leu131Glu) mutation has been reported to date. We report the case of a 32-year-old Japanese male with a history of cerebral hemorrhage and hydrocephalus at age 27 years. The patient was referred to our department after his sibling had been diagnosed with hereditary transthyretin amyloidosis. Twelve-lead electrocardiography exhibited poor R progression, and transthoracic echocardiography showed normal findings. ^99mTc-labelled pyrophosphate scintigraphy showed high accumulation in the heart. Histological tests using a right ventricular endomyocardial biopsy showed amyloid deposits and immunostaining only for transthyretin. Genetic analysis confirmed a novel missense variant, Leu111Glu, on the transthyretin gene. We diagnosed the patient with hereditary transthyretin amyloidosis, and the patient received genetic counseling. Patients with hereditary transthyretin amyloidosis carrying the Leu111Gln variant may present as a patient with a hydrocephalus-dominant phenotype. To the best of our knowledge, this is the first case report of the transthyretin Leu111Glu variant.

Hereditary transthyretin amyloidosis with the Leu111Gln variant has not been previously reported in Japan. While cardiac involvement progresses without overt abnormal findings on electrocardiogram and echocardiogram, ^99mTc-labelled pyrophosphate scintigraphy can be a useful tool for the early diagnosis of hereditary transthyretin amyloidosis. This mutation may result in a predominantly hydrocephalus phenotype, and organ damage is expected to progress rapidly. Therefore, early diagnosis and appropriate treatment are necessary.