Genetic study, histochemical analysis and neuroimaging profile in Brazilian patients with cadasil

Abstract

Analyze the histochemical aspect of granular osmiophilic material in cutaneous biopsy, evaluate morphometrically white matter in cerebral MRI and study of variants of the NOTCH3 gene in patients with suspected CADASIL (cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy). Human gDNA from freshly drawn peripheral blood samples was extracted using a commercial illustra bloodgenomic Prep Mini Spin Kit. Variants in exons 3 and 4 of the NOTCH3gene were screened by Sanger Sequencing method. Brain morphological evaluation by 3-Tesla MRI. For ultrastructural analysis, skin samples were fixed in 2.5% glutaraldehyde, postfixed in 1% osmium tetroxide, dehydrated in acetone and embedded in Epon. Analysis of vessel wall structure was performed by transmission electron microscopy on skin. 20 suspected cases were evaluated. We found fifteen patients to be heterozygous for the pathogenic allele variant c.457C>T (Arg153Cys; rs797045014*T) from the ten probably unrelated kindreds. One patient is heterozygous for the pathogenic allele c.328C>T (Arg110Cys; rs775836288*T), Figure1. All patients with pathogenic allele had MRI lesions; MRI morphometric analyses revealed higher lesion load in frontal and temporal lobes and in deep areas (internal and external capsule, basal ganglia, thalamus), brainstem and cerebellum; in one case we observed spinal cord involvement. We searched for granular Electron-dense Extracellular Material (GOM) located in the internal part of the media, reaching the basal lamina, in four patients (Figure2). For assessment of CADASIL, association between skin biopsy and electron microscopy, study of pathogenic variants in exons 3 and 4 of the NOTCH3gene and MRI morphometric study, increase the sensitivity for a correct diagnosis.