Infant With a Severe Form of <i>GLRX5</i> -Related Atypical Hyperglycinemia Exhibiting Novel Cardiac and Neurologic Disease Manifestations at Autopsy

Glutaredoxin 5 (GLRX5) is a mitochondrial protein encoded by the GLRX5 gene, which is essential for cellular redox homoeostasis, lipoic acid synthesis, and iron-sulfur cluster transfer. Rare cases of pathogenic GLRX5 mutations have been associated with sideroblastic anemia and non-ketotic hyperglycinemia with progressive spasticity and cavitating leukoencephalopathy. We report an 11-month-old child, who died following aspiration, with severe cardiomyocyte mitochondrial abnormalities and cerebral white matter degeneration in the context of a homozygous GLRX5 variant (c.208A>G, p.S70G).