IARS2 and infantile spasms: In this study, we reported two unrelated patients who presented with LS and had biallelic variants (c.1_390del and c.2450G > A, c.2122G > A and c.2090G > A) in IARS2. Among these variants, the variants c.2122G > A and c.2450G > A were previously reported in a patient diagnosed with LS and in a family with two Japanese siblings who exhibited milder symptoms of CAGSSS and West syndrome alongside LS, respectively.