MTNR1A and systemic lupus erythematosus: Later, the haplotype of MTNR1a/b and AANAT was identified; MTNR1a gene haplotype of CCTAT and CTAGT, and AANAT gene haplotype of GGG showed an increased risk in SLE susceptibility, but haplotype of TCTAT (MTNR1a) and CTG (AANAT) appeared to have a protective role.