title: Microcephaly with simplified gyration, epilepsy, and infantile diabetes linked to inappropriate apoptosis of neural progenitors.
abstract: We describe a syndrome of primary microcephaly with simplified gyral pattern in combination with severe infantile epileptic encephalopathy and early-onset permanent diabetes in two unrelated consanguineous families with at least three affected children. Linkage analysis revealed a region on chromosome 18 with a significant LOD score of 4.3. In this area, two homozygous nonconserved missense mutations in immediate early response 3 interacting protein 1 (IER3IP1) were found in patients from both families. IER3IP1 is highly expressed in the fetal brain cortex and fetal pancreas and is thought to be involved in endoplasmic reticulum stress response. We reported one of these families previously in a paper on Wolcott-Rallison syndrome (WRS). WRS is characterized by increased apoptotic cell death as part of an uncontrolled unfolded protein response. Increased apoptosis has been shown to be a cause of microcephaly in animal models. An autopsy specimen from one patient showed increased apoptosis in the cerebral cortex and pancreas beta cells, implicating premature cell death as the pathogenetic mechanism. Both patient fibroblasts and control fibroblasts treated with siRNA specific for IER3IP1 showed an increased susceptibility to apoptotic cell death under stress conditions in comparison to controls. This directly implicates IER3IP1 in the regulation of cell survival. Identification of IER3IP1 mutations sheds light on the mechanisms of brain development and on the pathogenesis of infantile epilepsy and early-onset permanent diabetes.
authors.affiliation: Department of Clinical Genetics, Erasmus MC, Rotterdam, The Netherlands.
authors.forename: Cathryn J
authors.initials: CJ
authors.lastname: Poulton
authors.forename: Rachel
authors.initials: R
authors.lastname: Schot
authors.forename: Sima Kheradmand
authors.initials: SK
authors.lastname: Kia
authors.forename: Marta
authors.initials: M
authors.lastname: Jones
authors.forename: Frans W
authors.initials: FW
authors.lastname: Verheijen
authors.forename: Hanka
authors.initials: H
authors.lastname: Venselaar
authors.forename: Marie-Claire Y
authors.initials: MC
authors.lastname: de Wit
authors.forename: Esther
authors.initials: E
authors.lastname: de Graaff
authors.forename: Aida M
authors.initials: AM
authors.lastname: Bertoli-Avella
authors.forename: Grazia M S
authors.initials: GM
authors.lastname: Mancini
mesh_terms: D000595:Amino Acid Sequence; D017209:Apoptosis / Q000187:drug effects; D001921:Brain / Q000187:drug effects / Q000378:metabolism / Q000473:pathology; D002352:Carrier Proteins / Q000737:chemistry / Q000235:genetics; D002675:Child, Preschool; D019295:Computational Biology; D003920:Diabetes Mellitus / Q000473:pathology*; D004827:Epilepsy / Q000150:complications* / Q000473:pathology*; D005190:Family; D017809:Fatal Outcome; D005260:Female; D005347:Fibroblasts / Q000187:drug effects / Q000378:metabolism / Q000473:pathology; D008040:Genetic Linkage / Q000187:drug effects; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008279:Magnetic Resonance Imaging; D008297:Male; D008565:Membrane Proteins / Q000737:chemistry / Q000235:genetics; D008831:Microcephaly / Q000150:complications* / Q000473:pathology; D008969:Molecular Sequence Data; D009154:Mutation / Q000235:genetics; D058953:Neural Stem Cells / Q000187:drug effects / Q000378:metabolism / Q000473:pathology*; D010375:Pedigree; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology
chemical_list: D002352:Carrier Proteins; C492451:IER3IP1 protein, human; D008565:Membrane Proteins; D014409:Tumor Necrosis Factor-alpha