Interestingly, hydroxyproline content, which is a measure for fibrillar collagen, was less useful for distinguishing HF hearts from donor hearts than the expression of the 12-gene panel, suggesting that the non-fibrillar collagens, TGFB1, CCL2, and TGFβ1-induced genes included in the panel are markers for HF fibrosis independent of the fibrillar collagens. Here, TGFB1 is linked to hydrops fetalis.