Following our finding that the heritable portion of TRPC6 gene expression in tissue from the LV is associated with a decline in LVEF in patients treated with chemotherapy and trastuzumab from the N9831 clinical trial, we sought to validate this finding in additional samples and to determine if the association was a direct result of chemotherapy or whether genetic variants at the TRPC6 locus simply increased a patient's risk of HF in general. The gene discussed is TRPC6; the disease is hydrops fetalis.