Signs and symptoms of GAII vary greatly depending on the age of onset and severity of the condition in each affected individual.
There are three main subtypes of GAII: the neonatal form with congenital anomalies, the neonatal form without congenital anomalies, and the late onset form. Newborns with the neonatal (first 4 weeks of life) form without congenital anomalies may have severe hypoglycemia, respiratory distress, low muscle tone, an odor of sweaty feet, liver (hepatomegaly), heart (cardiomyopathy) and kidney abnormalities.
In addition to these symptoms, neonates having GAII with congenital anomalies may also present with an abnormally large head (macrocephaly), high forehead, flat nasal bridge, malformed ears, genital abnormalities, brain malformations, enlarged weak heart (cardiomyopathy), fluid-filled renal cysts, and unusual facial features. Complete enzyme deficiency found in severely affected patients with the neonatal form is not compatible with life beyond the first few days/weeks of life.
Symptoms present in patients with the late onset form of GAII generally appear in childhood to adulthood, are less severe and highly variable. Muscle Weakness is the most common symptom of this late onset form and individuals may have intermittent Vomiting and hypoglycemia. Some of these patients may respond very well to high dose oral riboflavin treatment.