Clcn2, encoding a two-pore homodimeric chloride channel protein (CLC-2), is widely expressed in human tissues and is fundamental in ion and water brain homeostasis [3,4]. It may be involved in maintaining the balance of chloride ions in cells, which is related to many physiological functions. Loss-of-function mutations in Clcn2 have been linked to various disorders, highlighting its biological importance in normal physiological function [1-7,9].

Loss-of-function mutations in the Clcn2 gene are associated with CLCN2-related leukoencephalopathy (CC2L), a type of leukodystrophy characterized by intramyelinic edema [1]. Patients with CC2L may present with symptoms such as hand tremor, scanning speech, nystagmus, cerebellar ataxia, memory decline, tinnitus, dizziness, and macular atrophy [1]. Brain MRI shows diffuse white matter involvement of specific white matter tracts [1]. Additionally, germline mutations in Clcn2 have been described as a cause of familial hyperaldosteronism type II, and somatic (tumor-specific) mutations have been identified in aldosterone-producing adenomas [2,5]. Biallelic Clcn2 mutations can cause retinal degeneration by impairing retinal pigment epithelium phagocytosis and chloride channel function [3].

In conclusion, Clcn2 plays a crucial role in maintaining ion and water balance in the brain, and its dysfunction is associated with CC2L, familial hyperaldosteronism type II, and retinal degeneration. The study of Clcn2-related loss-of-function mutations in these diseases helps to understand the underlying pathophysiological mechanisms and may provide potential targets for diagnosis and treatment.