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Image by National Cancer Institute

The ASH1L gene, also known as KMT2H, provides instructions for making an enzyme, called lysine-specific methyltransferase 2H, that is found in many organs and tissues of the body. Lysine-specific methyltransferase 2H functions as a histone methyltransferase. Histone methyltransferases are enzymes that modify proteins called histones. Histones are structural proteins that attach (bind) to DNA and give chromosomes their shape. By adding a molecule called a methyl group to histones (a process called methylation), histone methyltransferases control (regulate) the activity of certain genes. Lysine-specific methyltransferase 2H appears to turn on (activate) certain genes that are especially important for development of the brain.

This gene encodes a member of the trithorax group of transcriptional activators. The encoded product functions as a histone methyltransferase specifically methylating 'Lys-36' of histone H3 (H3K36me).



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ASH1L Mutation is predominantly associated with neurological and neurodevelopmental disorders. 

Some of the other phenotypes observed in ASH1L Warriors

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At least seven ASH1L gene mutations have been identified in people with autism spectrum disorder (ASD), a varied condition characterized by impaired social skills, communication problems, and repetitive behaviors. Some ASH1L gene mutations associated with ASD change one building block (amino acid) in the lysine-specific methyltransferase 2H enzyme. Others delete genetic material in the ASH1L gene sequence or result in a premature stop signal that leads to an abnormally short enzyme. As a result of these mutations, the enzyme is nonfunctional. A lack of functional lysine-specific methyltransferase 2H enzyme disrupts histone methylation. The resulting changes in the expression of genes regulated by lysine-specific methyltransferase 2H affect brain development and increase the risk of ASD. Normal variations in other genes, as well as environmental risk factors, such as parental age, birth complications, and others that have not been identified, also affect an individual's risk of developing this complex condition.​


Stethoscope on the Cardiogram


Image by Alexander Popov
  • Absent small and homeotic disks protein 1 homolog

  • ASH1

  • ash1 (absent, small, or homeotic)-like

  • ASH1-like protein

  • ASH1L1

  • histone-lysine N-methyltransferase ASH1L

  • huASH1

  • KMT2H

  • lysine N-methyltransferase 2H

  • probable histone-lysine N-methyltransferase ASH1L


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