XBP1 and polycystic ovary syndrome: The other signal highlighted in the meta-analysis of lean PCOS, on chromosome 22, led by rs2228260, a synonymous SNP in XBP1 (Fig. 1; Supplementary Table 1), contained a total of 11 genome-wide significant variants Examination of the LD between these variants suggested that they were all likely representative of the same signal (all r2 = 1).