Allan Bayat
Copenhagen University Hospital
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Publication
Featured researches published by Allan Bayat.
Epilepsia | 2015
Allan Bayat; Helle Hjalgrim; Rikke S. Møller
Dravet syndrome is a severe infantile‐onset epileptic encephalopathy associated with mutations in the sodium channel alpha‐1 subunit gene SCN1A. We aimed to describe the incidence of Dravet syndrome in the Danish population. Based on a 6‐year birth cohort from 2004 to 2009, we propose an incidence of 1:22,000, which is higher than what has been established earlier. We identified 17 cases with SCN1A mutation–positive Dravet syndrome. Fifteen patients were found, by conventional Sanger sequencing. Two additional patients with clinical Dravet syndrome, but without a detectable SCN1A mutation by Sanger sequencing, were diagnosed with a SCN1A mutation after using a targeted next‐generation sequencing gene panel.
Acta Paediatrica | 2009
Allan Bayat; Astrid Christine Petersen; Margrethe Møller; Graziella Andersen; Finn Ebbesen
2. Paige DG, Bhogal BS, Black MM, Harper JI. Lichen planus pemphigoides in a chilld-immunopathological findings. Clin Exp Dermatol 1993; 18: 552–4. 3. Mora RG, Nesbitt LT Jr., Brantley JB. Lichen planus pemphigoides: clinical and immunofluorescent findings in four cases. J Am Acad Dermatol 1983; 8: 331–6. 4. Hofmann-Wellenhof R, Salmhofer W, Kerl H. Lichen planus pemphigoides in a 9-year-old child: successful treatment with topical corticosteroids. Pediatr Dermatol 1999; 16: 70–1. 5. Zlatkov N, Tsankov N, Pramatarov K, Konstantinov K. Bullous lichen planus and lichen planus pemphigoides. Dermatol Monatsschr 1988; 174: 339–44. 6. Harjai B, Mendiratta V, Kakkar S, Koranne RV. Childhood lichen planus pemphigoides–a rare entity. J Eur Acad Dermatol Venereol 2006; 20: 117–8.
JAMA Neurology | 2017
Carolien G.F. de Kovel; Steffen Syrbe; Eva H. Brilstra; Nienke E. Verbeek; Bronwyn Kerr; Holly Dubbs; Allan Bayat; Sonal Desai; Sakkubai Naidu; Siddharth Srivastava; Hande Cagaylan; Uluç Yiş; Carol J. Saunders; Martin B. Rook; Susanna Plugge; Hiltrud Muhle; Zaid Afawi; Karl-Martin Klein; Vijayakumar Jayaraman; Ramakrishnan Rajagopalan; Ethan M. Goldberg; Eric D. Marsh; Sudha Kilaru Kessler; Christina Bergqvist; Laura K. Conlin; Bryan L Krok; Isabelle Thiffault; Manuela Pendziwiat; Ingo Helbig; Tilman Polster
Importance Knowing the range of symptoms seen in patients with a missense or loss-of-function variant in KCNB1 and how these symptoms correlate with the type of variant will help clinicians with diagnosis and prognosis when treating new patients. Objectives To investigate the clinical spectrum associated with KCNB1 variants and the genotype-phenotype correlations. Design, Setting, and Participants This study summarized the clinical and genetic information of patients with a presumed pathogenic variant in KCNB1. Patients were identified in research projects or during clinical testing. Information on patients from previously published articles was collected and authors contacted if feasible. All patients were seen at a clinic at one of the participating institutes because of presumed genetic disorder. They were tested in a clinical setting or included in a research project. Main Outcomes and Measures The genetic variant and its inheritance and information on the patients symptoms and characteristics in a predefined format. All variants were identified with massive parallel sequencing and confirmed with Sanger sequencing in the patient. Absence of the variant in the parents could be confirmed with Sanger sequencing in all families except one. Results Of 26 patients (10 female, 15 male, 1 unknown; mean age at inclusion, 9.8 years; age range, 2-32 years) with developmental delay, 20 (77%) carried a missense variant in the ion channel domain of KCNB1, with a concentration of variants in region S5 to S6. Three variants that led to premature stops were located in the C-terminal and 3 in the ion channel domain. Twenty-one of 25 patients (84%) had seizures, with 9 patients (36%) starting with epileptic spasms between 3 and 18 months of age. All patients had developmental delay, with 17 (65%) experiencing severe developmental delay; 14 (82%) with severe delay had behavioral problems. The developmental delay was milder in 4 of 6 patients with stop variants and in a patient with a variant in the S2 transmembrane element rather than the S4 to S6 region. Conclusions and Relevance De novo KCNB1 missense variants in the ion channel domain and loss-of-function variants in this domain and the C-terminal likely cause neurodevelopmental disorders with or without seizures. Patients with presumed pathogenic variants in KCNB1 have a variable phenotype. However, the type and position of the variants in the protein are (imperfectly) correlated with the severity of the disorder.
Genome Medicine | 2018
Alexej Knaus; Jean Tori Pantel; Manuela Pendziwiat; Nurulhuda Hajjir; Max Zhao; Tzung Chien Hsieh; Max Schubach; Yaron Gurovich; Nicole Fleischer; Marten Jäger; Sebastian Köhler; Hiltrud Muhle; Christian Korff; Rikke S. Møller; Allan Bayat; Patrick Calvas; Nicolas Chassaing; Hannah Warren; Steven Skinner; Raymond J. Louie; Christina Evers; Marc Bohn; Hans Jürgen Christen; Myrthe van den Born; Ewa Obersztyn; Agnieszka Charzewska; Milda Endziniene; Fanny Kortüm; Natasha J Brown; Peter N. Robinson
BackgroundGlycosylphosphatidylinositol biosynthesis defects (GPIBDs) cause a group of phenotypically overlapping recessive syndromes with intellectual disability, for which pathogenic mutations have been described in 16 genes of the corresponding molecular pathway. An elevated serum activity of alkaline phosphatase (AP), a GPI-linked enzyme, has been used to assign GPIBDs to the phenotypic series of hyperphosphatasia with mental retardation syndrome (HPMRS) and to distinguish them from another subset of GPIBDs, termed multiple congenital anomalies hypotonia seizures syndrome (MCAHS). However, the increasing number of individuals with a GPIBD shows that hyperphosphatasia is a variable feature that is not ideal for a clinical classification.MethodsWe studied the discriminatory power of multiple GPI-linked substrates that were assessed by flow cytometry in blood cells and fibroblasts of 39 and 14 individuals with a GPIBD, respectively. On the phenotypic level, we evaluated the frequency of occurrence of clinical symptoms and analyzed the performance of computer-assisted image analysis of the facial gestalt in 91 individuals.ResultsWe found that certain malformations such as Morbus Hirschsprung and diaphragmatic defects are more likely to be associated with particular gene defects (PIGV, PGAP3, PIGN). However, especially at the severe end of the clinical spectrum of HPMRS, there is a high phenotypic overlap with MCAHS. Elevation of AP has also been documented in some of the individuals with MCAHS, namely those with PIGA mutations. Although the impairment of GPI-linked substrates is supposed to play the key role in the pathophysiology of GPIBDs, we could not observe gene-specific profiles for flow cytometric markers or a correlation between their cell surface levels and the severity of the phenotype. In contrast, it was facial recognition software that achieved the highest accuracy in predicting the disease-causing gene in a GPIBD.ConclusionsDue to the overlapping clinical spectrum of both HPMRS and MCAHS in the majority of affected individuals, the elevation of AP and the reduced surface levels of GPI-linked markers in both groups, a common classification as GPIBDs is recommended. The effectiveness of computer-assisted gestalt analysis for the correct gene inference in a GPIBD and probably beyond is remarkable and illustrates how the information contained in human faces is pivotal in the delineation of genetic entities.
Clinical Genetics | 2016
Allan Bayat; Saiqa Yasmeen; Allan M. Lund; Jytte Bieber Nielsen; Lisbeth Birk Møller
We describe the genotypes of the complete cohort, from 1967 to 2014, of phenylketonuria (PKU) patients in Denmark, in total 376 patients. A total of 752 independent alleles were investigated. Mutations were identified on 744 PKU alleles (98.9%). In total, 82 different mutations were present in the cohort. The most frequent mutation c.1315+1G>A (IVS12+1G>A) was found on 25.80% of the 744 alleles. Other very frequent mutations were c.1222C>T (p.R408W) (16.93%) and c.1241A>G (p.Y414C) (11.15%). Among the identified mutations, five mutations; c.532G>A (p.E178K), c.730C>T (p.P244S), c.925G>A (p.A309T), c.1228T>A (p.F410I), and c.1199+4A>G (IVS11+4A>G) have not been reported previously. The metabolic phenotypes of PKU are classified into four categories; ‘classical PKU’, ‘moderate PKU’, ‘mild PKU’ and ‘mild hyperphenylalaninemia’. In this study, we assigned the phenotypic outcome of three of the five novel mutations and furthermore six not previously classified mutations to one of the four PKU categories.
Genetics in Medicine | 2017
Livia Garavelli; Ivan Ivanovski; Stefano Giuseppe Caraffi; Daniela Santodirocco; Marzia Pollazzon; Duccio Maria Cordelli; Ebtesam M. Abdalla; P. Accorsi; Adam Mp; Chiara Baldo; Allan Bayat; E Belligni; Federico Bonvicini; Jeroen Breckpot; Bert Callewaert; Guido Cocchi; Goran Cuturilo; Koenraad Devriendt; Mary Beth P. Dinulos; Olivera Djuric; Roberta Epifanio; Francesca Faravelli; Debora Formisano; L. Giordano; Marina Grasso; Sabine Grønborg; Alessandro Iodice; Lorenzo Iughetti; Didier Lacombe; Massimo Maggi
Purpose:Mowat–Wilson syndrome (MWS) is a genetic disease characterized by distinctive facial features, moderate to severe intellectual disability, and congenital malformations, including Hirschsprung disease, genital and eye anomalies, and congenital heart defects, caused by haploinsufficiency of the ZEB2 gene. To date, no characteristic pattern of brain dysmorphology in MWS has been defined.Methods:Through brain magnetic resonance imaging (MRI) analysis, we delineated a neuroimaging phenotype in 54 MWS patients with a proven ZEB2 defect, compared it with the features identified in a thorough review of published cases, and evaluated genotype–phenotype correlations.Results:Ninety-six percent of patients had abnormal MRI results. The most common features were anomalies of corpus callosum (79.6% of cases), hippocampal abnormalities (77.8%), enlargement of cerebral ventricles (68.5%), and white matter abnormalities (reduction of thickness 40.7%, localized signal alterations 22.2%). Other consistent findings were large basal ganglia, cortical, and cerebellar malformations. Most features were underrepresented in the literature. We also found ZEB2 variations leading to synthesis of a defective protein to be favorable for psychomotor development and some epilepsy features but also associated with corpus callosum agenesis.Conclusion:This study delineated the spectrum of brain anomalies in MWS and provided new insights into the role of ZEB2 in neurodevelopment.Genet Med advance online publication 10 November 2016
European Journal of Medical Genetics | 2018
Allan Bayat; Michael Bayat; Ricardo Lozoya; Christian P. Schaaf
We report a novel patient with the phenotypic characteristics of Schaaf-Yang syndrome. In addition, the patient has a severe chronic digestive malfunction, rendering him dependent on intermittent enteral supplementation. To our knowledge, this is the first report of Schaaf-Yang syndrome associated with severe chronic digestive malfunction manifesting with both a malrotation and signs of a chronic intestinal pseudo-obstruction.
American Journal of Medical Genetics Part A | 2016
Allan Bayat; Igor Fijalkowski; Tobias Nicolai Andersen; Sura Azhar Abdulmunem; Jenneke van den Ende; Wim Van Hul
Mutations in the NOG gene give rise to a wide range of clinical phenotypes. Noggin, the protein encoded by this gene is a secreted modulator of multiple pathways involved in both bone and joint development. Proximal symphalangism is commonly observed in patients bearing mutations in this gene, however secondary symptomes are often found including typical facies with hemicylindrical nose with bulbous tip, hyperopia, reduced mobility of multiple joints, hearing loss due to stapes fixation, and recurrent pain from affected joints. With large variation of the phenotype both within and between affected families careful delineation of the genotype–phenotype correlation is needed. In this work we describe a Danish family suffering from SYNS1 due to a novel NOG gene mutation (C230Y). We provide detailed clinical description of the family members presenting rare phenotype of the shoulders shared by affected individuals but no hearing loss, further adding to the phenotypic variability of the syndrome. With these findings we broaden the understanding of NOG‐related‐symphalangism spectrum disorder.
Neurologia I Neurochirurgia Polska | 2018
Michael Bayat; Allan Bayat
Hemorrhage is not uncommon in cystic neoplasms but is a very rare occurrence in brain abscesses. A hemorrhage in the wall of a cyst usually signifies a tumor but an abscess may rarely have hemorrhages in the wall. Knowledge of this is important in order to avoid unnecessary surgery under the misdiagnosis of a hemorrhagic malignant tumor. We present a case of a pyogenic brain absces, demonstrating signal changes consistent with hemorrhage, mimicking a hemorrhagic tumor.
Journal of Neurology | 2018
Michael Bayat; Allan Bayat
Post-stroke pain is a well-known neuropathic pain syndrome but pain at the onset of stroke is a very rare occurrence. We wish to present a case where a stroke in the insular region caused acute-onset lateralized neuropathic pain.