Keith Hyland, PhD, and Phillip Pearl, MD, outline the hallmark signs and symptoms that patients with AADC deficiency may experience
Hyland: Hallmark symptoms I suppose would be hypotonia, developmental delay, you would have some type of movement disorder, dystonia, oculogyric crises, akinesia, dyskinesias. And also because of the norepinephrine and epinephrine you get autonomic symptoms and the autonomic symptoms essentially consist of ptosis, problems with maintaining body temperature, excess sweating, and oropharyngeal congestion.
Pearl: There can be a prominent nasal stuffiness, which sounds kind of funny. That’s very non-specific. Well, a lot of these manifestations are non-specific, and one needs to synthesize them and put them together to arrive at the correct diagnosis of AADC deficiency.
Some patients will present with intermittent or episodic hypoglycemia because there are problems with gluconeogenesis and the formation of glucose, and you can have a child present in crisis, in a metabolic crisis with hypoglycemia. And I’ve seen this and it may not be recognized that it’s AADC deficiency. So there are widespread ramifications and neurological impairments to this diagnosis.
Hyland: Not only do you get neurological symptoms, you also have, you also have problems with irritability. These children that have this disorder are incredibly irritable. They have long-lasting crying spells and they also have gastrointestinal problems. So, they can have diarrhea, constipation, and also big problems with gastro reflux.
Pearl: So how this presents is real low muscle tone, developmental impairment, oculogyric crises at about 2 or 3 months of age. Later, other areas of development are affected, not just gross motor, but fine motor and cognitive and verbal. Many of these children are completely nonverbal.