ZZZ3 and obesity due to melanocortin 4 receptor deficiency: To date, the largest known population-based GWAS of SevO was performed in 263,407 individuals of European ancestry and identified seven novel loci associated with different classes of obesity; two of which (HS6ST3 [heparan sulfate 6-O-sulfotransferase 3] and ZZZ3 (zinc finger ZZ-type containing 3) were associated with WHO Obesity Class II ([BMI] ≥35 kg/m2) [18].