While the early degeneration of D2 MSNs and impaired GABAergic transmission are well-documented, potassium chloride cotransporter 2 (KCC2), a key regulator of intracellular chloride (Cl−), and therefore GABAergic signaling, has not been characterized in D1 and D2 MSNs in HD. The gene discussed is SLC12A5; the disease is Huntington disease.