LY6K and hereditary palmoplantar keratoderma: A few human orthologs in the mouse of LY6 include LY6E, LY6K, Lynx1, Slurp1, and Gpihbp1. Knockout of these genes results in embryonic lethality, infertility in male mice, increased visual cortex plasticity, palmoplantar keratoderma with metabolic and neuromuscular abnormal phenotypes, and hypertriglyceridemia phenotype.