LEP and cancer: For example, a single nucleotide polymorphism (SNP) in LEP, consisting in G to A substitution at nucleotide -2548 upstream from ATG start site (LEP G-2548A, rs7799039), in locus 7q31.3, has been associated with increased leptin secretion in adipocytes [16–18], while the LEPR gene polymorphism, an A to G transition in exon 6 at nucleotide 668 from the start codon (Gln223Arg, rs1137101), in locus 1p31.3, has been associated with decreased BMI, higher leptin levels, and some types of cancers [19, 20].