A case has been reported in China of a patient with a rare variant of hereditary transthyretin amyloidosis (hATTR), known as Phe64Ser TTR, which is characterized by predominantly gastrointestinal amyloidosis.
The patient, reported in the Journal of Cardiovascular Medicine, underwent a technetium-99m pyrophosphate (Tc-99m PYP) scan that revealed the gastrointestinal involvement.
“In individuals with ATTR, gastrointestinal tract symptoms may arise from gastrointestinal amyloidosis and/or autonomic nervous amyloidosis,” the authors wrote. “A positive Tc-99m PYP scan of the gastrointestinal tract may indicate the presence of gastrointestinal amyloidosis, while in cases where gastrointestinal manifestations exist with negative findings on Tc-99m PYP scanning, autonomic nervous amyloidosis may be more likely.”
The patient presented initially at age 18 years with arrhythmia, chest pain, dyspnea, and lower limb edema, followed by heart failure at age 19 years. She underwent a Tc-99m PYP scan that revealed cardiac amyloidosis. Both she and her twin sister, who had died, had positive gastrointestinal Tc-99m PYP signals with uptake in the left colon and small intestine.
Read more about hATTR complications
The Tc-99m PYP scan also revealed significant involvement of the thyroid and spleen in both patients, including thyroid disease potentially caused by amyloidosis or another thyroid pathology. However, the scan was unable to differentiate between small intestine amyloidosis and that of the transverse colon and stomach, or between the left colon and left small intestine.
Given that mRNA silencers such as patisiran and inotersen are not yet available in China to treat neuropathy due to amyloidosis, the patient was prescribed vitamin B12, citicoline sodium, and mecobalamin, in combination with tafamidis.
The authors report the case to highlight the potential of bone tracer scintigraphy such as the Tc-99m PYP scan, in combination with signs and symptoms of malabsorption, to reveal the Phe64Ser TTR variant associated with gastrointestinal and systemic ATTR amyloidosis.
Reference
Chen J, Tang G. Possible gastrointestinal tract involvement in hereditary transthyretin amyloidosis identified by Technetium-99m pyrophosphate scan. J Cardiovasc Med. 2023 Jun 1;24(6):373-379. doi:10.2459/JCM.0000000000001471
