Brain magnetic resonance imaging (MRI) pattern recognition in Pol III-related leukodystrophies

Pol III-related leukodystrophies are caused by mutations in POLR3A and POLR3B genes and all share peculiar imaging and clinical features. The objectives of this study are (1) to define the neuroradiologic pattern in a cohort of POLR3A and POLR3B subjects and (2) to compare the neuroradiologic pattern of Pol III-related leukodystrophies with other hypomyelinating disorders. The magnetic resonance imaging (MRI) examinations of 13 patients with POLR3A and POLR3B mutations and of 14 patients with other hypomyelinating disorders were analyzed. All the subjects with Pol III-related leukodystrophies presented hypomyelination associated with T2 hypointensity of the thalami and/or the pallida. Twelve subjects (92%) presented T2 hypointensity of the optic radiations. Cerebellar atrophy was observed in most patients (92%). The combination of the analyzed criteria identified patients with Pol III-related leukodystrophies with a sensitivity of 84.6% and a specificity of 92.9%.