In PCOS cases, several groups have shown an enhanced level of serum APLN positively correlated with HOMA-IR and BMI (Sun et al., 2015; Roche et al., 2016; Bongrani et al., 2019), while one research reported a decreased serum APLN level which was positively associated with HOMA-IR and BMI (Altinkaya et al., 2014). This evidence concerns the gene APLN and polycystic ovary syndrome.