Teaching NeuroImage: Glutaredoxin-5-Associated Variant Nonketotic Hyperglycinemia.

A 5-year-old boy presented with subacute motor regression since age 2.5 years. Examination revealed spasticity of bilateral lower extremities, generalized dystonia, and pseudobulbar palsy. Investigations revealed raised plasma lactate (2.5 mmol/L, normal range 0.8-1.5 mmol/L) and no evidence of sideroblastic anemia. Neuroimaging showed cavitating leukoencephalopathy with involvement of long tracts (corticospinal, spinothalamic tracts) and dorsolateral columns of cervicothoracic cord (Figures 1 and 2). A next-generation sequencing test identified a novel homozygous missense variant (c.171C > A, p.Phe57Leu) in exon 1 of the Glutaredoxin-5 (GLRX5) gene.