To further investigate the relationship between PK2 and obesity, serum PK2 levels were divided into four quartiles according to its concentration in the entire cohort (quartile [Q] 1, <10654.9 pg/mL; Q2, 10654.9–13540.1 pg/mL; Q3, 13540.1–15857.4 pg/mL, and Q4, >15857.4 pg/mL). Here, PROK2 is linked to obesity due to melanocortin 4 receptor deficiency.