Considering that in our study, increased levels of TNF-α were associated with impaired endothelial function measured by FMD, as well as with a lower number of CD34+ cells after stimulation with G-CSF, we suggest that high TNF-α levels are one of the main factors affecting both the endothelium and the bone marrow function in patients with HF regardless of the cause of HF. The gene discussed is TNF; the disease is hydrops fetalis.