Fibromuscular dysplasia of the internal carotid artery associated with α₁-antitrypsin deficiency

OBJECTIVE: A deficiency of α₁-antitrypsin has been implicated in the development of various disorders affecting medium-sized arteries, including intracranial aneurysms, cervicocephalic arterial dissections, and fibromuscular dysplasia (FMD). We performed α₁-antitrypsin phenotyping in three consecutive patients who underwent bypass surgery for FMD of the extracranial internal carotid artery to test the hypothesis that α₁- antitrypsin deficiency is a genetic risk factor for the development of FMD. METHODS: The study population consisted of three women (aged 37, 49, and 53 years, respectively) who had bilateral internal carotid artery stenosis caused by FMD. The indications for surgery included ocular or cerebral ischemic symptoms in two patients and progressive stenosis in one patient. The diagnosis of FMD was confirmed by histological examination of the resected segment of artery. The α₁-antitrypsin phenotype was determined by isoelectric focusing in polyacrylamide gels. RESULTS: Two of the three patients had a heterozygous α₁-antitrypsin deficiency (PiMZ phenotype). Pathological examination of the resected arterial segment showed typical medial FMD with focal intimal fibroplasia in both patients with the PiMZ phenotype. CONCLUSION: These findings suggest that a heterozygous α₁- antitrypsin deficiency may be a genetic risk factor for the development of FMD of the internal carotid artery.