SNP Shot: Genomic Insights

Aromatic l-amino acid decarboxylase (AADC) deficiency is a genetic condition impacting how nerve cells communicate with each other.

Typically, the signs and symptoms of AADC deficiency become apparent during the first year of a child's life. Infants with this condition may exhibit significant delays in development, reduced muscle tone (hypotonia), muscle rigidity, difficulty with movement, and involuntary, writhing movements of the limbs (athetosis). They may also be lethargic, have feeding problems, be easily startled, and experience sleep problems. Individuals with AADC deficiency can also have oculogyric crises, characterized by unusual eye rotations, extreme irritability and restlessness, and pain, muscle spasms, and uncontrolled movements, particularly affecting the head and neck.

AADC deficiency can affect the autonomic nervous system, responsible for regulating involuntary bodily functions like blood pressure and temperature. This can lead to symptoms such as drooping eyelids (ptosis), constricted pupils (miosis), abnormal or impaired sweating, a stuffy nose, excessive drooling, impaired temperature regulation, low blood pressure (hypotension), acid reflux (gastroesophageal reflux), low blood sugar (hypoglycemia), fainting (syncope), and even cardiac arrest.

The symptoms of AADC deficiency often intensify later in the day or when the person is fatigued, and they tend to lessen after sleep.

Inheritance:

AADC deficiency follows an autosomal recessive inheritance pattern. This means that a person must inherit a mutated copy of the responsible gene from both parents to develop the condition. The parents, who each carry only one copy of the mutated gene, are usually unaffected and do not show symptoms of AADC deficiency themselves.