H19 and obesity due to melanocortin 4 receptor deficiency: Although lncRNAs are typically known for their tissue-specific expressions [121], certain lncRNAs, such as H19, are altered in several tissues under obesity, including the liver, adipose tissue, muscle, and the heart under specific conditions [122,123,124,125,126], making it hard to confidently determine the contribution of each tissue to circulating exo-lncRNAs.