Aromatic L-amino acid decarboxylase (AADC) deficiency is a genetic condition that affects the communication between the brain and other parts of the body causing development delays.

Genetic defects

AADC deficiency is caused by mutations in the dopa decarboxylase (DDC) gene, which carries the instructions to make the aromatic L-amino acid decarboxylase enzyme.

The nervous signals from the brain are relayed to the rest of the body via the nerve cells or neurons. These neurons use chemical messengers called neurotransmitters to transmit these signals. Dopamine and serotonin are two vital neurotransmitters. Dopamine plays a vital role in coordinating movement, learning, attention, emotions, and personality traits. Serotonin regulates mood, digestion, and sleep. Problems in the production of these neurotransmitters can have an impact on their function.

The production of dopamine and serotonin is a multi-step process. Dopamine synthesis starts with an amino acid (the building block of proteins) called tyrosine, which is first converted to L-dopa. The first step of serotonin synthesis begins with the conversion of amino acid tryptophan to 5-hydroxytryptophan. Next, the AADC enzyme facilitates the final steps in the process of converting L-dopa and 5-hydroxytryptophan to dopamine and serotonin, respectively. A mutation in the DDC gene impedes AADC production and decreases its activity, which in turn reduces dopamine and serotonin levels and leads to the symptoms of AADC deficiency.

Inheritance of AADC deficiency

There are 23 pairs of chromosomes in every cell in our body. Twenty-two of these are called autosomes, and the 23rd pair is called the sex chromosomes. Each parent contributes one chromosome to the pair. Every gene in an autosome exists in two identical copies. The DDC gene is located on chromosome 7, an autosome.

AADC deficiency is inherited in an autosomal recessive manner, meaning that the disease only develops if both copies of the DDC gene are mutated. Individuals who have one copy of the mutated gene are called carriers of AADC deficiency. They usually do not exhibit any symptoms, but carry the risk of passing the disease on to their children.

 

Last updated: Sept. 10, 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.

Vijaya Iyer is a freelance science writer for BioNews Services. She has contributed content to their several disease-specific websites, including cystic fibrosis, multiple sclerosis, muscular dystrophy, among others. She holds a PhD in Microbiology from Kansas State University, where her research focused on molecular biology, bacterial interactions, metabolism, and animal models to study bacterial infections. Following the completion of her PhD, Dr. Iyer went on to complete three postdoctoral fellowships at Kansas State University, University of Miami and Temple University. She joined BioNews Services to utilize her scientific background and writing skills to help patients and caregivers remain abreast with important scientific breakthroughs.
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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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Vijaya Iyer is a freelance science writer for BioNews Services. She has contributed content to their several disease-specific websites, including cystic fibrosis, multiple sclerosis, muscular dystrophy, among others. She holds a PhD in Microbiology from Kansas State University, where her research focused on molecular biology, bacterial interactions, metabolism, and animal models to study bacterial infections. Following the completion of her PhD, Dr. Iyer went on to complete three postdoctoral fellowships at Kansas State University, University of Miami and Temple University. She joined BioNews Services to utilize her scientific background and writing skills to help patients and caregivers remain abreast with important scientific breakthroughs.
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