From OMIM
Glutaric aciduria II (GA2) is an autosomal recessively inherited disorder of fatty acid, amino acid, and choline metabolism. It differs from GA I (GA1; 231670) in that multiple acyl-CoA dehydrogenase deficiencies result in large excretion not only of glutaric acid, but also of lactic, ethylmalonic, butyric, isobutyric, 2-methyl-butyric, and isovaleric acids. GA II results from deficiency of any 1 of 3 molecules: the alpha (ETFA) and beta (ETFB) subunits of electron transfer flavoprotein, and electron transfer flavoprotein dehydrogenase (ETFDH). The clinical picture of GA II due to the different defects appears to be indistinguishable; each defect can lead to a range of mild or severe cases, depending presumably on the location and nature of the intragenic lesion, i.e., mutation, in each case (Goodman, 1993; Olsen et al., 2003). The heterogeneous clinical features of patients with MADD fall into 3 classes: a neonatal-onset form with congenital anomalies (type I), a neonatal-onset form without congenital anomalies (type II), and a late-onset form (type III). The neonatal-onset forms are usually fatal and are characterized by severe nonketotic hypoglycemia, metabolic acidosis, multisystem involvement, and excretion of large amounts of fatty acid- and amino acid-derived metabolites. Symptoms and age at presentation of late-onset MADD are highly variable and characterized by recurrent episodes of lethargy, vomiting, hypoglycemia, metabolic acidosis, and hepatomegaly often preceded by metabolic stress. Muscle involvement in the form of pain, weakness, and lipid storage myopathy also occurs. The organic aciduria in patients with the late-onset form of MADD is often intermittent and only evident during periods of illness or catabolic stress (summary by Frerman and Goodman, 2001). Importantly, riboflavin treatment has been shown to ameliorate the symptoms and metabolic profiles in many MADD patients, particularly those with type III, the late-onset and mildest form (Liang et al., 2009).  http://www.omim.org/entry/231680

From MedlinePlus Genetics
Glutaric acidemia type II is an inherited disorder that interferes with the body's ability to break down proteins and fats to produce energy. Incompletely processed proteins and fats can build up in the body and cause the blood and tissues to become too acidic (metabolic acidosis).

Glutaric acidemia type II usually appears in infancy or early childhood as a sudden episode called a metabolic crisis, in which acidosis and low blood glucose (hypoglycemia) cause weakness, behavior changes such as poor feeding and decreased activity, and vomiting. These metabolic crises, which can be life-threatening, may be triggered by common childhood illnesses or other stresses.

In the most severe cases of glutaric acidemia type II, affected individuals may also be born with physical abnormalities. These may include brain malformations, an enlarged liver (hepatomegaly), a weakened and enlarged heart (dilated cardiomyopathy), fluid-filled cysts and other malformations of the kidneys, unusual facial features, and genital abnormalities. Glutaric acidemia type II may also cause a characteristic odor resembling that of sweaty feet.

Some affected individuals have less severe symptoms that begin later in childhood or in adulthood. In the mildest forms of glutaric acidemia type II, muscle weakness developing in adulthood may be the first sign of the disorder.  https://medlineplus.gov/genetics/condition/glutaric-acidemia-type-ii