GHITM and keratoconus: The variants in the genes POLR2M and GHITM are excluded to be in association with keratoconus because the first encodes a subunit of a specific form of RNA polymerase II that act as negative regulator of transcriptional activation by the mediator complex [37], and the second encodes a growth hormone inducible transmembrane protein that is required for the mitochondrial tubular network and cristae organization [38].