Adenylosuccinate Lyase Deficiency Overview Adenylosuccinate lyase deficiency (ADSL deficiency) is a rare inherited metabolic disorder characterized by developmental delay, seizures, learning/intellectual disability and autism related behaviors. Based on the age of onset and the severity of the symptoms it can be classified in three forms: Fatal neonatal form, a very severe form that is present before or at birth Childhood form or severe form (type I) which begins in infancy or early childhood Slowly progressive form or mild form (type II), a milder form that worsens more gradually over time Signs and symptoms across these forms vary greatly from person to person and may include slowing of thought and physical movement (psychomotor impairment), autism related traits such as repetitive behaviors and failure to make eye contact, seizures, progressive loss of muscle tissue (muscle wasting), difficulty eating and drinking due to the psychomotor problems (secondary feeding problems) an...