In light of these observations and the previously documented causative role of amino acid changes in nebulette for endocardial fibroelastosis in humans [54], it is tempting to speculate that our finding that regulatory NEBL alleles may be associated with MMVD via their effect on nebulette expression in papillary muscle could underlie the observed link between papillary muscle fibrosis and deteriorating mitral valve function in dogs affected by MMVD. This evidence concerns the gene NEBL and endocardial fibroelastosis.