Quantitative functional assay identifies fitness defect in genome-engineered ATRIP c.829+5G>T and ATRIP c.829+2T>G cells. (a) Schematic representation of CRISPR-SelectTIME process for cell fitness testing. The depletion region of the ATR and ATRIP genes are indicated. The CRISPR-Select cassettes for all the variants were transfected on day 2. Yellow cross indicates the various editing outcomes on target gene. The cell samples from day 2 (D2) and day 12 (D12) were collected and lysed for DNA extraction. PCR amplified the target edited sites of each sample and products were analyzed by NGS sequencing. (b) Schematic illustration of the modeled compound heterozygous (hez) and homozygous (hoz) ATRIP variants at the transcript level. (c) Cell fitness of MCF10A mono-allelic cells with the ATR and ATRIP variants. Each symbol within the bar represents an independent experiment. Each variant has three independent biological replicates. Mean and SEM are shown. Data of D12 is normalized to D2. **P < 0.01, ***P < 0.001, ns: non-significant (two-tailed paired t tests).