NOTCH2 mutations in Alagille syndrome

• Published in: Journal of medical genetics Vol. 49; no. 2; pp. 138 - 144
• Main Authors: Kamath, Binita Maya, Bauer, Robert C, Loomes, Kathleen M, Chao, Grace, Gerfen, Jennifer, Hutchinson, Anne, Hardikar, Winita, Hirschfield, Gideon, Jara, Paloma, Krantz, Ian D, Lapunzina, Pablo, Leonard, Laura, Ling, Simon, Ng, Vicky Lee, Hoang, Phuc Le, Piccoli, David A, Spinner, Nancy Bettina
• Format: Journal Article
• Language: English
• Published: London BMJ Publishing Group Ltd 01.02.2012; BMJ Publishing Group; BMJ Publishing Group LTD
• Subjects: Alagille syndrome; Alagille Syndrome - genetics; Animals; Bile ducts; Biological and medical sciences; Cell Line; DNA Mutational Analysis; Facies; Fundamental and applied biological sciences. Psychology; Gallbladder diseases; Gastroenterology. Liver. Pancreas. Abdomen; Gene Expression; General aspects. Genetic counseling; Genetic Association Studies; Genetics of eukaryotes. Biological and molecular evolution; HEK293 Cells; Humans; JAGGED1; Ligands; Liver. Biliary tract. Portal circulation. Exocrine pancreas; Medical genetics; Medical sciences; Mice; Molecular and cellular biology; Mutagenesis; Mutation; notch signalling pathway; NOTCH2; Other diseases. Semiology; Patients; Phenotype; Pulmonary arteries; Receptor, Notch2 - genetics; Receptor, Notch2 - metabolism; Signal Transduction; Vertebrae; United States > US; California; Vascular disease; Human; Portal circulation disease; Cardiovascular disease; Digestive diseases; Arteriohepatic dysplasia; Genetics; Mutation
• ISSN: 0022-2593; 1468-6244; 1468-6244
• DOI: 10.1136/jmedgenet-2011-100544

BackgroundAlagille syndrome (ALGS) is a dominant, multisystem disorder caused by mutations in the Jagged1 (JAG1) ligand in 94% of patients, and in the NOTCH2 receptor in <1%. There are only two NOTCH2 families reported to date. This study hypothesised that additional NOTCH2 mutations would be present in patients with clinical features of ALGS without a JAG1 mutation.MethodsThe study screened a cohort of JAG1-negative individuals with clinical features suggestive or diagnostic of ALGS for NOTCH2 mutations.ResultsEight individuals with novel NOTCH2 mutations (six missense, one splicing, and one non-sense mutation) were identified. Three of these patients met classic criteria for ALGS and five patients only had a subset of features. The mutations were distributed across the extracellular (N=5) and intracellular domains (N=3) of the protein. Functional analysis of four missense, one nonsense, and one splicing mutation demonstrated decreased Notch signalling of these proteins. Subjects with NOTCH2 mutations demonstrated highly variable expressivity of the affected systems, as with JAG1 individuals. Liver involvement was universal in NOTCH2 probands and they had a similar prevalence of ophthalmologic and renal anomalies to JAG1 patients. There was a trend towards less cardiac involvement in the NOTCH2 group (60% vs 100% in JAG1). NOTCH2 (+) probands exhibited a significantly decreased penetrance of vertebral abnormalities (10%) and facial features (20%) when compared to the JAG1 (+) cohort.ConclusionsThis work confirms the importance of NOTCH2 as a second disease gene in ALGS and expands the repertoire of the NOTCH2 related disease phenotype.