DLK1 and Infertility: Finally, DLK1 encodes a growth regulator involved in infertility and genetic central precocious puberty in males that has been proposed as a link between metabolism and fertility (Rockett et al., 2004; Gomes et al., 2019; Palumbo et al., 2023); interestingly, DLK1 was found to be overexpressed in testicular tissue from SCO infertile patients (Bonache et al., 2014).