Abstract
Objective: Hereditary transthyretin amyloidosis (ATTRv) represents a diagnostic challenge considering the great variability of clinical presentation and multiorgan involvement. In the present study, we report the prevalence of kidney involvement and kidney function over time in a cohort of ATTRv patients with different transthyretin gene mutations. Patients and Methods: For this study, we systematically collected data from all patients with a diagnosis of ATTRv followed at the Neurology Unit of Fondazione Policlinico Universitario A. Gemelli IRCCS. Kidney involvement was defined as presence of estimated glomerular filtration rate (eGFR) < 60 mL/min/1.73 m2 obtained with CKD-EPI equation, abnormal urinary protein excretion (UPE) (>150 mg/24 h) and/or albuminuria > 30 mg/24 h (or mg/g creatinine). The analysis included data from 46 patients with 122 measurements of serum creatinine. Results: Among the 46 patients included in the analysis, kidney involvement was present in 37%, with 15% showing reduced eGFR and 22% abnormal UPE (63% of patients with available UPE data). No single predictor was associated with either eGFR values or its slope over time. Conclusions: Kidney involvement is quite common in patients with ATTRv regardless of the underlying genetic variant. In particular, abnormal UPE appears to be a common feature of the disease.
Highlights
The term “amyloidosis” encompasses different disease entities deriving from conformational changes in native, soluble proteins that misfold and aggregate extracellularly into insoluble, highly ordered fibrils, leading to dysfunction of different organ and tissue [1]
While kidney involvement is well-known and common in AL and amyloid A (AA) forms of amyloidosis, very few data are available on kidney involvement in hereditary transthyretin amyloidosis (ATTRv), especially in late-onset patients from non-endemic areas [1,2,3]
We report the prevalence of kidney involvement and trajectories of kidney function over time in a cohort of ATTRv patients with different mutations coming from Italy, a non-endemic region
Summary
The term “amyloidosis” encompasses different disease entities deriving from conformational changes in native, soluble proteins that misfold and aggregate extracellularly into insoluble, highly ordered fibrils, leading to dysfunction of different organ and tissue [1]. Kidney is a potential target organ [2]. Proteins capable of producing amyloid deposits involving the kidney include immunoglobulin lights chains (AL), immunoglobulin heavy chains (AH), serum amyloid A (AA), fibrinogen Aα-chain (AFib), lysozyme (Alys), apolipoprotein AI (AApoAI), apolipoprotein AII (AApoAII), Leukocyte Chemotactic Factor-2 (ALECT2), beta-2 microglobulin (Aβ2M, dialysis-related amyloidosis), and transthyretin (ATTR) [1,2]. ATTRv is a rare disease due to mutations in the gene encoding TTR and is characterized by multisystem extracellular deposition of amyloid [3]. More than 120 TTR variants have been described as a cause of ATTRv, the most frequent being the Val30Met mutation [4]
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