Thus, additional studies are still needed to better understand the degree to which GADD45A is required for muscle atrophy in contexts that have been investigated to some extent (e.g., muscle denervation, limb immobilization) and in other clinically important contexts (e.g., advanced age, critical illness, diabetes, cancer, renal failure, heart failure, chronic pulmonary disease, spinal cord injury, weight loss medications and surgeries, Cushing syndrome, chronic infections). This evidence concerns the gene GADD45A and Cushing syndrome due to macronodular adrenal hyperplasia.