SLC12A5 and Parkinson disease: KCC2 has an important role in maintaining neuronal chloride homeostasis and has been found to be associated with many severe neurological, psychiatric and neurodegenerative disorders, including epilepsy, neuropathic pain, schizophrenia, autism spectrum disorders and Parkinson's disease (Ben-Ari, 2017, Silayeva et al., 2015).