PDCD1 and myelodysplastic syndrome: As shown in Figure 3, there was a clear trend suggesting that high expression of PDCD1 or TIGIT is associated with poor OS for MDS patients younger than 60 years of age, although the P value of TIGIT is not statistically significant (PDCD1: HR = 7.09, P = 0.025; TIGIT: HR > 100, P = 0.070).