Table 1.

Description of the main clinical, electroencephalographic, brain imaging, and genetic features recorded in SPAX5 cases harboring bi‐allelic mutations in AFG3L2.

	Pierson et al., 20115	Eskandrani et al., 20171					Muona et al., 201513		Tunc et al., 20198	This case
Age at onset	2 years	8 months	8 months	8 months	8 months	8 months	10 years	10 years	20 years	2 years
Sex	M	F	M	F	M	F	M	F	M	M
Clinical features at last examination	Progressive motor degeneration, dysarthria, dysphagia	Severe development‐al delay. Microcephaly	Severe development‐al delay. Microcephaly	Severe development‐al delay. Microcephaly	Severe development‐al delay. Microcephaly	Severe development‐al delay. Microcephaly	SCA 28, spastic ataxia and severe myoclonic epilepsy	Progressively worsening myoclonus and ataxia	Limb and gait ataxia, dysarthria	Episodes triggered by exercise
Epilepsy	+	+	+	+	+	+	+	+	‐	‐
Electroencephalogram	Diffuse disorganization, F‐C spikes/waves	Hypsarrhyth‐mia	Hypsarrhyth‐mia	Consistent with myoclonic seizures	Hypsarrhyth‐mia	Hypsarrhyth‐mia	Data not available	Data not available	Unremarkable alpha‐EEG	Normal
Brain MRI	Moderate cerebellar atrophy	Bilateral involvement of putamina and caudate nuclei	Bilateral involvement of putamina	Bilateral involvement of putamina	Bilateral involvement of putamina	Bilateral involvement of putamina and caudate nuclei	Data not available	Data not available	Cerebellar atrophy	Bilateral involvement of globi pallidi, pars reticulata of the substantia nigra
AFG3L2 mutation	c.1847G.A/ pTyr616Cy (homozygous)	c.1714G> A/ p.Ala572Thr (homozygous)	c.1714G> A/ p.Ala572Thr (homozygous)	c.1714G> A/ p.Ala572Thr (homozygous)	c.1714G> A/ p.Ala572Thr (homozygous)	c.1714G> A/ p.Ala572Thr (homozygous)	c.1875G> A/ p.Met625Ile (homozygous)	c.1875G> A/ p.Met625Ile (homozygous)	c.2167G> A/ p.Val723Met; c.1847A> G/ p.Tyr616Cys (comppund heterozyg.)	c.634dupG/ p.Val212Glyfs*4; c.2167G> A/ p.Val723Met (compound heterozygous)

Bold typesetting indicate features observed in the patient described in this work.