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http://hdl.handle.net/2445/174439
Title: | Bi-allelic JAM2 Variants Lead to Early-Onset Recessive Primary Familial Brain Calcification |
Author: | Schottlaender, Lucia V. Abeti, Rosella Jaunmuktane, Zane Macmillan, Carol Chelban, Viorica O'Callaghan, Benjamin McKinley, John Maroofian, Reza Efthymiou, Stepanie Athanasiou Fragkouli, Alkyoni Forbes, Raeburn Soutar, Marc P.M. Livingston, John H. Kalmar, Bernadett Swayne, Orlando Hotton, Gary SYNAPS Study Group Pittman, Alan Mendes de Oliveira, João Ricardo de Grandis, Maria Richard Loendt, Angela Launchbury, Francesca Althonayan, Juri McDonnell, Gavin Carr, Aisling S. Khan, Suliman Beetz, Christian Bisgin, Atil Tug Bozdogan, Sevcan Begtrup, Amber Torti, Erin Greensmith, Linda Giunti, Paola Morrison, Patrick J. Brandner, Sebastian Aurrand Lions, Michael Houlden, Henry Cormand Rifà, Bru |
Keywords: | Calcificació Malalties neurodegeneratives Calcification Neurodegenerative Diseases |
Issue Date: | 5-Mar-2020 |
Publisher: | Cell Press |
Abstract: | Primary familial brain calcification (PFBC) is a rare neurodegenerative disorder characterized by a combination of neurological, psychiatric, and cognitive decline associated with calcium deposition on brain imaging. To date, mutations in five genes have been linked to PFBC. However, more than 50% of individuals affected by PFBC have no molecular diagnosis. We report four unrelated families presenting with initial learning difficulties and seizures and later psychiatric symptoms, cerebellar ataxia, extrapyramidal signs, and extensive calcifications on brain imaging. Through a combination of homozygosity mapping and exome sequencing, we mapped this phenotype to chromosome 21q21.3 and identified bi-allelic variants in JAM2. JAM2 encodes for the junctional-adhesion-molecule-2, a key tight-junction protein in blood-brain-barrier permeability. We show that JAM2 variants lead to reduction of JAM2 mRNA expression and absence of JAM2 protein in patient's fibroblasts, consistent with a loss-of-function mechanism. We show that the human phenotype is replicated in the jam2 complete knockout mouse (jam2 KO). Furthermore, neuropathology of jam2 KO mouse showed prominent vacuolation in the cerebral cortex, thalamus, and cerebellum and particularly widespread vacuolation in the midbrain with reactive astrogliosis and neuronal density reduction. The regions of the human brain affected on neuroimaging are similar to the affected brain areas in the myorg PFBC null mouse. Along with JAM3 and OCLN, JAM2 is the third tight-junction gene in which bi-allelic variants are associated with brain calcification, suggesting that defective cell-to-cell adhesion and dysfunction of the movement of solutes through the paracellular spaces in the neurovascular unit is a key mechanism in CNS calcification. |
Note: | Reproducció del document publicat a: https://doi.org/10.1016/j.ajhg.2020.02.007 |
It is part of: | American Journal of Human Genetics, 2020, vol. 106, num. 3, p. 412-421 |
URI: | http://hdl.handle.net/2445/174439 |
Related resource: | https://doi.org/10.1016/j.ajhg.2020.02.007 |
ISSN: | 0002-9297 |
Appears in Collections: | Articles publicats en revistes (Genètica, Microbiologia i Estadística) |
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