Grik2, also known as GluR6, encodes an ionotropic glutamate receptor subunit. Glutamate receptors are crucial in the central nervous system for synaptic transmission and plasticity, being involved in various physiological and pathological processes [4].

In the context of diseases, Grik2 has been implicated in multiple conditions. In Chinese children, certain single nucleotide polymorphisms (SNPs) of Grik2 are related to epilepsy susceptibility. For example, the rs4840200-T allele and rs3213607-A allele carriers have a higher risk of epilepsy, and an interaction between rs4840200 and rs9390754 also increases the risk [1]. In urothelial carcinoma, Grik2 is expressed at a higher level in cancer stem-like cells (CSCs)/cancer-initiating cells (CICs) isolated as ALDH1high cells. Knockdown of Grik2 decreases sphere-forming and invasion abilities, while overexpression increases these abilities and tumorigenicity, suggesting its role in maintaining CSCs/CICs. Higher levels of Grik2 expression are related to poorer prognosis in urinary tract carcinoma cases [2]. In a study on bipolar manic patients in the Chinese Han population, the rs2227283 polymorphism of Grik2 is related to aggressive behaviors, with the A/A genotype and A allele increasing the risk of aggressive behavior [3]. Mutations in Grik2 have also been found to underlie diverse neurodevelopmental disorders. Heterozygous de novo variants in Grik2 in individuals cause neurodevelopmental deficits including intellectual disability, and specific mutations are associated with features like severe epilepsy and hypomyelination [4].

In conclusion, Grik2 is an important gene encoding a glutamate receptor subunit, playing a role in synaptic function. Through genetic association and functional studies, it has been shown to be involved in epilepsy, urothelial carcinoma, bipolar mania-related aggressive behaviors, and neurodevelopmental disorders. These findings from different research models contribute to understanding the complex biological functions of Grik2 and its implications in various disease conditions.