FXYD domain-containing ion transport regulator 6 (FXYD6 encodes the protein phosphohippolin and is located at the 11q23.3. It can be found in all human tissues except blood. FXYD6 in humans is primarily in the brain, with highest levels of expression found in the prefrontal cortex, amygdala, hypothalamus, and occipital lobe. FXYD6 is up-regulated in hepatocellular carcinoma (HCC) and it enhances the migration and proliferation of HCC cells. Therapy targeting FXYD6 could potentially benefit the clinical treatment toward HCC patients. FXYD6 is also associated with mental diseases. Mutations in the FXYD6 gene, or in sequences close to this gene, can predispose to schizophrenia which is known to be strongly heritable. FXYD6 was also found to be significantly downregulated in a Tg2576 mouse model of Alzheimer's disease (AD) brain and hippocampus. FXYD6 is a novel regulator of Na,K-ATPase expressed in the inner ear.