The lysine-specific demethylase 6A (KDM6A), also termed “Ubiquitously transcribed tetratricopeptide repeat on chromosome X” (UTX) is a 154 kDa protein coded by the KDM6A gene on chromosome Xp11.3. The gene is 5,438 bp long and contains 29 exons. It belongs to a family of Jumonji (JmjC) domain-containing enzymes which impact the demethylation of H3K27me2/3. H3K27me2/3 indicates the 27th amino acid on histone H3 which is known to represent a repressive histone modification. KDM6A regulates the transcription and expression of downstream genes, thereby regulating cell fate and functional cell characteristics. Depending on the molecular context, KDM6A can either promote or suppress cell growth. In evolving tissues, KDM6A is implicated in myogenesis, cardiac development, pancreas development, neural stem cell differentiation and immune cell functions. KDM6A is often mutated in various cancer types including bladder cancer, plasmacytoma, renal cell carcinoma, prostate cancer, and others. Mutations of KDM6A are a cause for Kabuki syndrome, a rare congenital anomaly syndrome characterized by intellectual disability, growth retardation, and multiple congenital abnormalities.