The expanding phenotype of COL4A1 and COL4A2 mutations: clinical data on 13 newly identified families and a review of the literature

• Published in: Genetics in medicine Vol. 17; no. 11; pp. 843 - 853
• Main Authors: Meuwissen, Marije E. C., Halley, Dicky J. J., Smit, Liesbeth S., Lequin, Maarten H., Cobben, Jan M., de Coo, René, van Harssel, Jeske, Sallevelt, Suzanne, Woldringh, Gwendolyn, van der Knaap, Marjo S., de Vries, Linda S., Mancini, Grazia M. S.
• Format: Journal Article
• Language: English
• Published: New York Nature Publishing Group US 01.11.2015; Elsevier Limited
• Subjects: 692/420/2489/144; 692/699/75/593/1370; Alleles; Anterior Eye Segment - abnormalities; Biomedicine; Brain - pathology; Cerebral Hemorrhage - diagnosis; Cerebral Hemorrhage - genetics; Cohort Studies; Collagen Type IV - genetics; Eye Abnormalities - diagnosis; Eye Abnormalities - genetics; Eye Diseases, Hereditary; Family; Gene Order; Genetic Association Studies; Genetic Loci; Genotype; Human Genetics; Humans; Laboratory Medicine; Leukomalacia, Periventricular - diagnosis; Leukomalacia, Periventricular - genetics; Magnetic Resonance Imaging - methods; Mutation; Pedigree; Phenotype; Porencephaly - diagnosis; Porencephaly - genetics; review; phenotype; familial porencephaly; cerebral hemorrhage
• ISSN: 1098-3600; 1530-0366
• DOI: 10.1038/gim.2014.210

Two proα1(IV) chains, encoded by COL4A1 , form trimers that contain, in addition, a proα2(IV) chain encoded by COL4A2 and are the major component of the basement membrane in many tissues. Since 2005, COL4A1 mutations have been known as an autosomal dominant cause of hereditary porencephaly. COL4A1 and COL4A2 mutations have been reported with a broader spectrum of cerebrovascular, renal, ophthalmological, cardiac, and muscular abnormalities, indicated as “ COL4A1 mutation–related disorders.” Genetic counseling is challenging because of broad phenotypic variation and reduced penetrance. At the Erasmus University Medical Center, diagnostic DNA analysis of both COL4A1 and COL4A2 in 183 index patients was performed between 2005 and 2013. In total, 21 COL4A1 and 3 COL4A2 mutations were identified, mostly in children with porencephaly or other patterns of parenchymal hemorrhage, with a high de novo mutation rate of 40% (10/24). The observations in 13 novel families harboring either COL4A1 or COL4A2 mutations prompted us to review the clinical spectrum. We observed recognizable phenotypic patterns and propose a screening protocol at diagnosis. Our data underscore the importance of COL4A1 and COL4A2 mutations in cerebrovascular disease, also in sporadic patients. Follow-up data on symptomatic and asymptomatic mutation carriers are needed for prognosis and appropriate surveillance. Genet Med 17 11, 843–853.