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Alexander disease (AD) is a progressive disorder of the white matter of the central nervous system (CNS). The three types of AD are categorized by age of onset: infantile, juvenile, and adult. Affected infants develop a megalencephalic leukodystrophy, seizures, spasticity, ataxia, and psychomotor retardation. Infantile AD frequently leads to death within a decade after the diagnosis. Juvenile and adult forms of AD have a more slowly progressive course and are characterized by ataxia, bulbar signs and spasticity. Rosenthal fibers, observed in the astrocytes of affected individuals upon autopsy, are a hallmark feature of AD. These cytoplasmic inclusions are made up of glial acidic fibrillary protein (GFAP) and small heat-shock proteins. MRI has proven to be a useful tool for diagnosing AD, and often shows high signal intensity of white matter in the frontal area and basal ganglia. Alexander disease is usually sporadic and is most often caused by de novo heterozygous mutations in the GFAP gene. The recurrence risk, even when both parents are negative for GFAP mutations, is unknown and may thus warrant consideration of prenatal diagnosis for couples who have had an affected child. There is one report of a clinically-diagnosed Alexander disease patient with apparent autosomal recessive mutations in the NDUFV1 gene.
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Zou et al. Whole exome sequencing: an effective and comprehensive genetic testing approach for leukodystrophy [abstract submitted] To be presented at the 2017 ASHG Annual Genetics Meeting, October 17-21, Orlando, FL.