Five members of the NCKX (SLC24) family are all able to exchange one Ca2+ and one K+ for four Na+. SLC24A5 (NCKX5, located on the trans-Golgi membrane) is the prediminant K+-dependent Na+/Ca2+ exchanger in melanocytes and is one of a handful of genes thought to play a role in determining human skin colour. Defects in SLC24A5 can cause oculocutaneous albinism 6 (OCA6; MIM:113750), a disorder characterised by a reduction or complete loss of melanin in the skin, hair and eyes. Patients with this condition show accompanying eye symptoms. Mutations causing OCA6 are W591* and L454Ffs*33 (Mondal et al. 2012, Wei et al. 2013).