AADC deficiency is most common neurotransmitter disorder in study
Scientists in India reported on 29 children at care center over 10 years
A new study reports that aromatic L-amino acid decarboxylase (AADC) deficiency was the most common neurotransmitter disorder seen at a clinic in India over the last decade.
The study, “Treatable and preventable causes of inborn errors of metabolism: Cohort of neurotransmitter disorders in children from India,” was published in Brain and Development.
Neurotransmitters are signaling molecules nerve cells use to communicate with each other and the rest of the body. AADC deficiency is an ultra-rare genetic disorder wherein an enzyme is missing that’s needed to produce certain neurotransmitters, namely dopamine and serotonin. Abnormally low levels of the signaling molecules give rise to disease symptoms.
AADC deficiency isn’t the only disorder characterized by abnormalities in neurotransmitter levels. Here, scientists in India reported on outcomes from 29 children with various neurotransmitter disorders who received care at a specialty center between 2015 and 2024.
“This study aims to describe the spectrum of clinical presentation, laboratory, imaging features, and genetic profiles of children diagnosed with neurotransmitter disorders and to assess the treatment modalities and clinical outcomes in these children,” wrote the researchers, who emphasized that studies of neurotransmitter disorders are important because certain parts of the country, especially southern India, have high rates of children born to parents who are close biological relatives, which may increase the risk of rare genetic conditions.
The need for greater awareness of AADC deficiency
AADC deficiency was the most common disorder identified. Seven of the 29 children were diagnosed with this rare disorder and, in three cases, the children were born to consanguineous parents.
All the children with AADC deficiency showed symptoms that included developmental delay, motor impairment, and issues with feeding and sleeping. Most had seizures, and all had experienced oculogyric crises, which are atypical fixed eye movements often seen with this disorder.
In all the AADC patients, symptoms appeared in infancy and were relatively severe and, even with treatments like vitamin B6, most were unable to walk or engage in personal hygiene without assistance. The average age at the onset of symptoms in children with AADC deficiency was 5 months, but most weren’t diagnosed until they were 1 year or older.
Outcomes for children with other neurotransmitter disorders varied. Ddisability tended to be mild in some conditions, while in others it was usually more severe. One death was reported, which occurred in a child with AADC deficiency, shortly after a diagnosis, due to pneumonia.
The researchers said their study shines a light on AADC and other neurotransmitter disorders in India, where these conditions often go undiagnosed and untreated. More research as well as policies are needed to provide the best possible care for families affected by these diseases.
“With a significant lack of awareness among practicing physicians and the public, these disorders continue to be underreported, especially in the marginalized regions,” the researchers wrote. “Being a large country with limited resources, India needs to formulate national guidelines and schemes to identify these children, provide early diagnosis, and appropriate management.”
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