Angiotensin-converting enzyme (ACE) gene (21 kb) is located in the chromosome 17,long arm, region 23, and contains 24 introns.7 It would be ideal to predict the individual response totherapy as well as the potential adverse effects of drugs in the treatment of HF.With advances in molecular biology and genetics, there has been an increasing needfor a redefinition of diseases based on their biochemical processes rather thantheir phenotypic features. This evidence concerns the gene ACE and hydrops fetalis.