U1 snRNA is an experimental treatment being developed for aromatic L-amino acid decarboxylase (AADC) deficiency.

What is AADC deficiency?

AADC deficiency is a rare disorder caused by mutations in a gene called DDC, which provides instructions for making an important enzyme (AADC) in the brain. AADC is involved in making two important signaling molecules in the brain (dopamine and serotonin). Mutations in DDC mean that not enough AADC is made, resulting in not enough serotonin and dopamine in the brain, causing the symptoms of the disease.

In order to make a protein from a gene (a DNA sequence within the genome), a temporary copy of the gene has to be made. This is called a messenger RNA or mRNA. This mRNA must then be processed to produce a mature mRNA that is ready to be “translated” into a protein. The processing of this mRNA involves editing out some non-coding sequences (called introns). This process is tightly controlled. Some mutations in DDC can cause the processing to stall or fail, meaning that no AADC protein is made.

How could U1 snRNA treat AADC deficiency?

U1 snRNA is a small, non-coding RNA (i.e. the RNA does not code for a protein) that is part of the complex involved in mRNA maturation. By introducing a modified form of U1 snRNA to the brain, it may be possible for cells to overcome the stall during mRNA maturation that prevents AADC protein from being made. The modified snRNA recognizes the specific mutations in the DDC mRNA, correcting the editing process so that a more normal protein can be made.

U1 snRNA in research

Researchers in Taiwan recently conducted a study in which they described the modified U1 snRNA that they designed to treat some forms of AADC deficiency. The results of this study were published in the scientific journal Human Molecular Genetics.

The authors performed an experiment, demonstrating that the snRNA would correct the editing events of DDC mRNA maturation. They followed up this experiment with a test in a mouse model of AADC deficiency. They used a virus to deliver the modified U1 snRNA to the brains of the mice. Following treatment, the mice showed improved production of dopamine and serotonin, and their survival was also improved.

The authors concluded that these results were promising, but more research is needed to translate these findings into human clinical trials.

 

Last updated: Sept. 23, 2019.

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AADC News is strictly a news and information website about the disease. It does not provide medical advice, diagnosis, or treatment. This content is not intended to be a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or other qualified healthcare providers with any questions you may have regarding a medical condition. Never disregard professional medical advice or delay in seeking it because of something you have read on this website.

Emily holds a Ph.D. in Biochemistry from the University of Iowa and is currently a postdoctoral scholar at the University of Wisconsin-Madison. She graduated with a Masters in Chemistry from the Georgia Institute of Technology and holds a Bachelors in Biology and Chemistry from the University of Central Arkansas. Emily is passionate about science communication, and, in her free time, writes and illustrates children’s stories.
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Özge has a MSc. in Molecular Genetics from the University of Leicester and a PhD in Developmental Biology from Queen Mary University of London. She worked as a Post-doctoral Research Associate at the University of Leicester for six years in the field of Behavioural Neurology before moving into science communication. She worked as the Research Communication Officer at a London based charity for almost two years.
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Emily holds a Ph.D. in Biochemistry from the University of Iowa and is currently a postdoctoral scholar at the University of Wisconsin-Madison. She graduated with a Masters in Chemistry from the Georgia Institute of Technology and holds a Bachelors in Biology and Chemistry from the University of Central Arkansas. Emily is passionate about science communication, and, in her free time, writes and illustrates children’s stories.
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