The TERC G319A mutation impairs TERC:TERT interaction. (A) Telomere restriction fragment length (TRF) analysis of normal (WT) iPSCs, 3 independent TERC-mutant iPSC clones (cl), and TERC-mutant fibroblasts. (B) Top left, Representative Northern blot of TERC RNA from WT, TERC-mutant iPSCs, and TERC-mutant fibroblasts. Top right, Relative TERC levels are shown in the graph. Bottom, Sequencing of TERC cDNA from TERC-mutant iPSCs. (C) Left, Schematic of TERC RNA in complex with TERT and dyskerin. Right, Sequencing of TERC RT-PCR amplicons isolated from TERT RNP (top) and dyskerin RNP (bottom) isolated by immunoprecipitation (IP) from TERC-mutant iPSCs. (D) Restriction fragment length polymorphism (RFLP) of TERC amplicons from dyskerin or TERT IP of patient iPSCs (lanes 5-8). The HincII site created by the G319A mutation is depicted on the right. Lanes 1-4 show digest patterns of amplicons from WT (319G) and mutant (319A) plasmid DNA. Products were separated by agarose gel electrophoresis and band intensity was quantified using ImageLab. n.s., not significant.