HEY1 and thyroiditis: Moreover, gene expression data strengthen our hypotheses that GDF11 is involved in respiratory and thyroid disease pathogenesis and that HEY1 regulates GDF11. Through these efforts, we report novel relationships between GDF11 and disease, suggesting GDF11 may exert its effects by acting on inflammatory pathways, in contrast to its formerly assumed role as a rejuvenating factor in basic aging.