Setd1a, a lysine-methyltransferase, is a member of the Trithorax-related Set1 H3K4 methyltransferases conserved from yeast to human [3]. It plays a critical role in chromatin-mediated regulation of gene expression, and is involved in various cell cycle regulatory processes [4]. Setd1a is essential for embryonic development, and in adult mice, it is required for the establishment of definitive hematopoiesis [3].

Mouse models with a heterozygous loss-of-function mutation of Setd1a exhibit alterations in axonal branching and cortical synaptic dynamics, along with working memory deficits, suggesting its role in schizophrenia-related phenotypes. Reinstating Setd1a expression in adulthood can rescue cognitive deficits, and pharmacological antagonism of its counteracting demethylase LSD1 can fully rescue the behavioral and morphological deficits in these mice [1]. In humans, heterozygous variants of Setd1a are associated with a novel neurodevelopmental syndrome characterized by global developmental delay, intellectual disability, subtle facial dysmorphisms, and behavioral and psychiatric problems [2].

In conclusion, Setd1a is crucial for normal development and function, especially in the nervous system. Studies using gene-knockout mouse models have revealed its significant role in schizophrenia-related phenotypes and a novel neurodevelopmental syndrome, providing potential targets for therapeutic interventions in these disease areas.