CEPT1 and Insulin resistance: Biallelic variants in PCYT1A have been associated with cone‐rod dystrophy, either isolated or in combination with spondylometaphyseal dysplasia (MIM#123695).21, 22 Additionally, congenital lipodystrophy, fatty liver, severe insulin resistance, and diabetes were seen in two patients, providing evidence for an additional and essential role of PCYT1A‐generated PC in the normal function of white adipose tissue and insulin action.23 The final step from CDP choline to PC is performed by choline phosphotransferase 1 (CHPT1) or choline/ethanolamine phosphotransferase 1 (CEPT1, CEPT1).