CTSL and obesity due to melanocortin 4 receptor deficiency: The LR-MØ cluster in the differential lung network also contains a number of genes implicated in lipid storage disorders, including HEXB, GLB1, and NPC2. Several other LR-MØ cluster genes have been shown to be important for regulating cholesterol trafficking genes in an animal model of obesity, including CTSB, CTSL, and NPC2 [51].