Table 1.

Documented cases of subependymal nodules in patients with biochemical and genetic testing confirming glutaric acidemia type 1

	Proband	Herskovitz et al. (2013)	Korman et al. (2007)	Pierson et al. (2015)
Sex/background	Female, Caucasian	Male, Iraqi Jewish	Male, Palestinian Arab	Female, Hispanic Mexican
Age of diagnosis	2 months old	56 years old	30 years old	55 years old
Comorbidities	Idiopathic intracranial hypertension	None reported	None reported	Crohn’s disease
Neurologic symptoms	Migrainous and IIH headaches, mild learning disability, recent onset slurred speech with left facial weakness/numbness	30-year history of pain in feet, gradual weakness in legs, speech disturbance, and incontinence	Borderline IQ, normal neurological exam; otherwise “asymptomatic”; discovered after seeking prenatal genetic counseling as he was paternal uncle of another patient in the case series	Bilateral lower extremity spasticity, numbness, and paresthesias
MRI findings	Callosal and periventricular white matter changes, age discordant parenchymal atrophy, and multifocal subependymal nodules (a type of heterotopia or disorganized brain tissue) in the lateral ventricles	Communicating hydrocephalous, bilateral frontotemporal atrophy, bilateral temporal arachnoid cysts, prominent periventricular and deep leukodystrophy, and subependymal cauliflower-like mass lesions	Patchy signal changes in the corpus callosum with wart-like mass lesions extending from the ependymal lining into the lateral ventricles in the upper part in the ventricular system and showing some contrast enhancement, resembling subependymal nodules found in tuberous sclerosis	Extensive bilateral white matter changes in the periventricular deep and subcortical white matter tracts; multiple subependymal nodules projecting into lateral ventricles; temporal lobe hypoplasia; normal striatum and corpus callosum
GCDH gene mutations	Homozygous for the c.1204 C>T, p.R402W pathogenic variant	Previously reported homozygous Gly101Arg mutation	Compound heterozygosity of a novel variant (c. 578_579 insTCA; pThr193_R194insHis) and known pathogenic mutation (c.877G>A; p.Ala293Thr)	Compound heterozygosity of a novel variant (c.1219 C>G; pLeu407Val) and known pathogenic mutation (c.848delT;pL283RfsX8)