In a study on hATTR, serum retinol-binding protein 4 (RBP4) concentration was lower in patients with hATTR V122I amyloidosis; also a lower concentration of B-type natriuretic peptide (BNP) and transtiretin (TTR), as well as, a higher concentration of Troponin I (TrI) and hematocrit have been reported [126]. The gene discussed is TTR; the disease is amyloidosis.