Stag1, a component of the STAG subunit within the core cohesin complex, plays a crucial role in processes like chromosome segregation and gene transcription as part of the cohesin pathway [1,4]. Cohesinopathies, rare neurodevelopmental disorders, can arise from its dysfunction [1].

Mutations in Stag1 have been identified in 17 individuals from 16 families with unspecific syndromic intellectual disability. These patients had common facial features, some had mild microcephaly and epilepsy [1]. In hematopoietic stem and progenitor cells, Stag1 and Stag2 have distinct roles. While concurrent loss of Stag2 and Stag1 abrogated hematopoiesis, Stag2 loss alone led to decreased chromatin accessibility and transcription of lineage-specification genes [2]. Moreover, STAG2-deficient cancers show a synthetic lethal interaction with Stag1, making Stag1 a potential therapeutic target [3].

In summary, Stag1 is essential for chromosome-related functions and gene regulation. Studies on Stag1, especially through patient cases and cell-based functional analysis, have revealed its significance in neurodevelopmental disorders and cancer, highlighting its potential as a therapeutic target in STAG2-deficient cancers.