Brain Calcifications in Adult-Onset Genetic Leukoencephalopathies: A Review.

Importance: Adult-onset genetic leukoencephalopathies and leukodystrophies are increasingly recognized as a heterogeneous group of disorders with new diagnostic approaches and potential treatments. In the new era of genomics, the challenging interpretation of individual genetic variations requires an accurate phenotypic description and classification. Clinical and magnetic resonance imaging (MRI)-based approaches have been proposed to improve the diagnostic process of adult-onset leukoencephalopathies. Cerebral calcifications, when associated with white matter hyperintensities, are of major importance in the decision-making process to focus the diagnosis among the diversity of rare causes. Observations: This literature review demonstrated that the morphologic features and topography of the calcifications observed in a careful combined analysis of computed tomographic and MRI scans may help indicate the diagnosis of adult-onset genetic leukoencephalopathies. Vascular genetic leukoencephalopathies are an important cause of leukoencephalopathy with calcifications. Among them, COL4A1-related disorders are frequently associated with spotlike calcifications in the basal ganglia. Adult-onset leukoencephalopathy with axonal spheroids, a probably underestimated disorder, is associated with a specific pattern of calcifications: small, symmetric, sparing the basal ganglia, and a stepping stone appearance in the frontal pericallosal region. Moreover, disorders primarily associated with basal ganglia calcifications, such as primary familial brain calcifications, can be associated with marked leukoencephalopathy. Conclusions and Relevance: The number of identified causes of adult-onset genetic leukoencephalopathies has recently increased. A diagnostic algorithm should take into account the pattern of calcifications to better target the genetic analyses.