BSCL2 and metabolic disease: Besides adipose tissue, seipin is also highly expressed in the testis.1, 9, 10 It was noticed that Bscl2−/− males were infertile during previous study of seipin deficiency in adipose tissue loss and metabolic disorders.8 A recent study demonstrated that BSCL2 mutations in a man and seipin deficiency in mice led to teratozoospermia and male infertility due to impaired testicular phospholipid homeostasis.10