SOHLH1 is a basic helix-loop-helix transcription factor essential for germline development in both sexes. In males, it suppresses genes required for spermatogonial stem cell maintenance while inducing differentiation-associated genes 1. In females, SOHLH1 is preferentially expressed in oocytes and required for oogenesis, coordinating follicular formation by regulating downstream factors including Nobox and Figla 1. SOHLH1 functions as part of a regulatory network with other oocyte transcription factors; it cross-regulates and directly interacts with LHX8 and FIGLA to control gene networks governing oocyte growth and differentiation 2. SOHLH1 also cooperatively represses Stra8 expression with SOHLH2, helping coordinate the transition from germ cell differentiation to meiosis 3. Mutations in SOHLH1 are associated with primary ovarian insufficiency and 46,XX gonadal dysgenesis in females 4, as well as male infertility with azoospermia or oligozoospermia. Recent evidence suggests SOHLH1 may also function as a tumor suppressor in glioma, where it inhibits glioma stem-like cell stemness through the Wnt/β-catenin pathway 5. These diverse functions reflect the gene's broader expression pattern in human tissues beyond the germline, including somatic cells of the gonad and various other organs 6.