Biolo et al. reported that patients with AL amyloidosis had significantly higher serum MMP9 and TIMP-1 levels than those in patients with ATTR amyloidosis with the same level of left ventricular hypertrophy, and subendocardial myocardial biopsy samples also showed increased expression of MMP9 and TIMP1 [88]. This evidence concerns the gene MMP9 and left ventricular hypertrophy.