Specifically in iCCA, various DNA damage response-related genes exhibit mutations or alterations, including PTEN, BRCA 1/2 (1.9% and 4.4%), ATM (5.7%), ATR (5.1%), ARID1A (13%), TP53, CDKN2A, POLD1, POLE, IDH 1 (20%), BAP1 (7.4%), BARD1 (2.5%), CHK 1/2 (1% and 1.9%), PALB2 (1.9%) and PBRM1 (12%) [109,180,181]. The gene discussed is POLD1; the disease is infantile convulsions and choreoathetosis.