Cystatin-D belongs to the family of cysteine proteinase inhibitors.29 Cysteine proteases have been implicated in the pathological remodelling of the heart that occurs in response to stress or injury, contributing to the development of fibrosis, hypertrophy, and apoptosis in the heart.30 Our study is the first reporting on the role of cystatin-D in HF. This evidence concerns the gene CST5 and hydrops fetalis.