LIG4 and liver disorder: While KIN appears to be the result of genomic instability and mitotic abnormalities in tubular epithelial cells induced by homozygous mutations in the FNA1 DNA repair enzyme, and endogenous oxidative stress was demonstrated as a key source of DNA damage in FAN1-deficient kidneys [25], the morphologic substrate and pathophysiology of liver disease in FAN1-mutation remain an enigma.