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ClC-2 is a plasma membrane chloride channel with widespread expression in the human body, including the brain. Its function is still being studied, although it is thought to have a role in ion and water homoeostasis in the brain. ClC-2 is part of a complex containing GlialCAM and MLC1. Both these genes are associated with autosomal recessive human leukodystrophies with intramyelinic oedema. Biallelic mutations in CLCN2, encoding the ClC-2 channel, have been reported in patients with a rare form of leukoencephalopathy with ataxia (LKPAT; MIM #615651). No peculiar neurological features have been reported for this disease, although slight visual impairment due to chorioretinopathy or optic atrophy, mild ataxia, learning disabilities, and headaches are recurrent symptoms in patients. However, MRI shows a typical diagnostic pattern that consists of white matter signal abnormalities in the posterior limbs of the internal capsules, cerebral peduncles, pontine pyramidal tracts and in the middle cerebellar peduncles, associated with lower apparent diffusion coefficient values in most cases. Specific anomalies of brainstem auditory evoked potentials (BAEP) have also been described.1–3
Here, we report on a 52-year-old Moroccan woman presenting with mild and asymptomatic bilateral optic atrophy detected at a routine ophthalmological examination for presbyopia. Best-corrected high-contrast visual acuity was 20/20 in both eyes. Anterior segment and intraocular pressures were normal, and pupillary reflexes were present. On fundus biomicroscopy, mild pallor and excavation of the optic …
Contributors EG designed the experimental plan, performed experiments, analysed data, and drafted and revised the paper. GV, PB, DD, CME and MTG contributed to the clinical definition to the clinical, neuroradiological and ophthalmological definition of the patient phenotype. NLB, CD, CM, SC, EDG, EP, MF and AB contributed to the experimental work and/or performed data analysis and interpretation. All authors revised the paper.
Funding This work was supported by MURST60% and Associazione ‘EE Rulfo per la Genetica Medica’ (to AB).
Competing interests None declared.
Patient consent Obtained.
Ethics approval Internal Review Board Committee of the Department of Medical Sciences (University of Torino).
Provenance and peer review Not commissioned; externally peer reviewed.
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