Movement disorder and neuronal migration disorder due to ARFGEF2 mutation

Area of Science:

• Neurogenetics
• Developmental Neuroscience
• Movement Disorders

Background:

• ARFGEF2 mutations are linked to brain malformations.
• The precise phenotypic spectrum and underlying mechanisms remain incompletely understood.

Purpose of the Study:

• To characterize the phenotype associated with novel ARFGEF2 mutations.
• To explore the potential pathomechanisms of the observed neurological deficits.

Main Methods:

• Clinical case report detailing neurological examination and neuroimaging.
• Genetic analysis identifying compound heterozygous ARFGEF2 mutations (c.2031_2038dup and c.3798_3802del).
• Review of ARFGEF2 function in cellular processes.

Main Results:

• A child presented with severe choreadystonic movement disorder, bilateral periventricular nodular heterotopia (BPNH), and secondary microcephaly.
• Brain MRI revealed bilateral putaminal hyperintensity, BPNH, and generalized atrophy.
• Loss of ARFGEF2 function impacts vesicle trafficking, cell proliferation/apoptosis, and neurotransmitter receptor function.

Conclusions:

• Novel ARFGEF2 mutations contribute to a severe neurodevelopmental phenotype including movement disorder and brain malformations.
• Dysfunctional ARFGEF2 likely underlies BPNH and microcephaly through disrupted cellular processes.
• The basal ganglia, particularly the putamen, may be uniquely vulnerable to ARFGEF2 loss, potentially due to degeneration or neurotransmitter receptor mislocalization.