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The role of somatic genetic variants in the pathogenesis of intracranial-aneurysm formation is unknown. We identified a 23-year-old man with progressive, right-sided intracranial aneurysms, ipsilateral to an impressive cutaneous phenotype. The index individual underwent a series of genetic evaluations for known connective-tissue disorders, but the evaluations were unrevealing. Paired-sample exome sequencing between blood and fibroblasts derived from the diseased areas detected a single novel variant predicted to cause a p.Tyr562Cys (g.149505130T>C [GRCh37/hg19]; c.1685A>G) change within the platelet-derived growth factor receptor β gene (PDGFRB), a juxtamembrane-coding region. Variant-allele fractions ranged from 18.75% to 53.33% within histologically abnormal tissue, suggesting post-zygotic or somatic mosaicism. In an independent cohort of aneurysm specimens, we detected somatic-activating PDGFRB variants in the juxtamembrane domain or the kinase activation loop in 4/6 fusiform aneurysms (and 0/38 saccular aneurysms; Fisher's exact test, p < 0.001). PDGFRB-variant, but not wild-type, patient cells were found to have overactive auto-phosphorylation with downstream activation of ERK, SRC, and AKT. The expression of discovered variants demonstrated non-ligand-dependent auto-phosphorylation, responsive to the kinase inhibitor sunitinib. Somatic gain-of-function variants in PDGFRB are a novel mechanism in the pathophysiology of fusiform cerebral aneurysms and suggest a potential role for targeted therapy with kinase inhibitors., (Published by Elsevier Inc.)

True aneurysms of the internal mammary artery are rare and have been described in association with vasculitis or connective tissue disorders. Herein, we describe 2 cases of familial internal mammary artery aneurysms (IMAs) in 2 sisters with SMAD3 mutation. The older sister presented at the age of 54 years with an incidental diagnosis of a multilobed right IMA and the younger sister presented several years earlier with a ruptured left IMA aneurysm at the age of 49 years. Both sisters had Debakey type I aortic dissections prior to the IMA aneurysm presentation. To our knowledge, this is the first time IMA aneurysms have been described in siblings with SMAD3 mutation. In our experience, endovascular repair is a feasible and safe treatment option. An assessment of the entire arterial tree is recommended in patients diagnosed with SMAD3 mutations., (Copyright © 2017 Elsevier Inc. All rights reserved.)