Defective SLC9A6 causes X-linked, syndromic mental retardation,, Christianson type (MRXSCH)

SLC9A6 encodes the sodium/hydrogen exchanger 6 NHE6, a protein ubiquitously expressed but most abundant in mitochondria-rich tissues such as brain, skeletal muscle and heart. It is located on endosomal membranes and thought to play a housekeeping role in pH homeostasis in early endosomes. It mediates the electroneutral exchange of protons for Na+ and K+ across the early and recycling endosome membranes. Defects in SLC9A6 can cause mental retardation, X-linked, syndromic, Christianson type (MRXSCH; MIM:300243), a syndrome characterised by profound mental retardation, epilepsy, ataxia and microcephaly. MRXSCH shows phenotypic overlap with Angelman syndrome.

Summary from Reactome (R-HSA-5619092), read 2026-09-23.