Additionally, previous studies reported that obesity was related with more advanced and biologically adverse tumors, such as larger tumor size, more lymph node involvement, higher proportion of ER-negative, triple negative tumors, grade III, or high Ki-67 index, and this could not be reproduced in our study (16, 33, 34), which may be explained by our study only including the luminal population. The gene discussed is MKI67; the disease is obesity due to melanocortin 4 receptor deficiency.