The relative expression of GJA1 gene (known as Connexin CX43 gene) was significantly up-regulated by treatment of melatonin in fresh (2.79-fold in MF vs. 1-fold in CF) and vitrified (8.72-fold in MV vs. 3.67-fold in CV) embryos (Fig 1). Here, GJA1 is linked to cystic fibrosis.