Elise Schaefer1, Corinne Collet2, David Genevieve3, Marie Vincent3, Dietmar R Lohmann4, Elodie Sanchez3, Chantal Bolender5, Marie-Madeleine Eliot6, Gudrun Nürnberg7, Maria-Rita Passos-Bueno8, Dagmar Wieczorek4, Lionel van Maldergem9, Bérénice Doray10. 1. 1] Service de Génétique Médicale, Hôpitaux Universitaires de Strasbourg, CHU de Hautepierre, Strasbourg, France [2] Laboratoire de Génétique Médicale, INSERM U1112, Faculté de Médecine, Université de Strasbourg, Strasbourg, France. 2. Service de Biochimie et de Biologie Moleculaire, Hôpital Lariboisière, INSERM U606, Assistance Publique-Hôpitaux de Paris, Paris, France. 3. Service de Génétique Médicale, CHRU Montpellier, Université de Montpellier 1, Montpellier, France. 4. Institut für Humangenetik, Universitätsklinikum Essen, Universität Duisburg-Essen, Essen, Germany. 5. Service de Pédiatrie, Centre Hospitalier de Haguenau, Haguenau, France. 6. Service ORL, Hôpitaux Universitaires de Strasbourg, CHU de Hautepierre, Strasbourg, France. 7. Center for Genomics, University of Cologne, Cologne, Germany. 8. Department of Genetics and Evolutive Biology, Human Genome Center, Institute of Bioscience, University of Sao Paulo, Sao Paulo, Brazil. 9. Centre de Génétique Humaine, Université de Franche-Comté, Besançon, France. 10. 1] Service de Génétique Médicale, Hôpitaux Universitaires de Strasbourg, CHU de Hautepierre, Strasbourg, France [2] Laboratoire de Génétique Médicale, INSERM U1112, Faculté de Médecine, Université de Strasbourg, Strasbourg, France [3] Current affiliation: Service de Génétique, CHU la Réunion, Hôpital Félix Guyon, Saint-Denis, France.
Abstract
PURPOSE: Treacher Collins syndrome is a mandibulofacial dysostosis caused by mutations in genes involved in ribosome biogenesis and synthesis. TCOF1 mutations are observed in ~80% of the patients and are inherited in an autosomal dominant manner. Recently, two other genes have been reported in <2% of patients--POLR1D in patients with autosomal dominant inheritance, and POLR1C in patients with autosomal recessive inheritance. METHODS: We performed direct sequencing of TCOF1, POLR1C, and POLR1D in two unrelated consanguineous families. RESULTS: The four affected children shared the same homozygous mutation in POLR1D (c.163C>G, p.Leu55Val). This mutation is localized in a region encoding the dimerization domain of the RNA polymerase. It is supposed that this mutation impairs RNA polymerase, resulting in a lower amount of mature dimeric ribosomes. A functional analysis of the transcripts of TCOF1 by real-time quantitative reverse transcription-polymerase chain reaction was performed in the first family, demonstrating a 50% reduction in the index case, compatible with this hypothesis. CONCLUSION: This is the first report of POLR1D mutation being responsible for an autosomal recessive inherited Treacher Collins syndrome. These results reinforce the concept of genetic heterogeneity of Treacher Collins syndrome and underline the importance of combining clinical expertise and familial molecular analyses for appropriate genetic counseling.
PURPOSE: Treacher Collins syndrome is a mandibulofacial dysostosis caused by mutations in genes involved in ribosome biogenesis and synthesis. TCOF1 mutations are observed in ~80% of the patients and are inherited in an autosomal dominant manner. Recently, two other genes have been reported in <2% of patients--POLR1D in patients with autosomal dominant inheritance, and POLR1C in patients with autosomal recessive inheritance. METHODS: We performed direct sequencing of TCOF1, POLR1C, and POLR1D in two unrelated consanguineous families. RESULTS: The four affected children shared the same homozygous mutation in POLR1D (c.163C>G, p.Leu55Val). This mutation is localized in a region encoding the dimerization domain of the RNA polymerase. It is supposed that this mutation impairs RNA polymerase, resulting in a lower amount of mature dimeric ribosomes. A functional analysis of the transcripts of TCOF1 by real-time quantitative reverse transcription-polymerase chain reaction was performed in the first family, demonstrating a 50% reduction in the index case, compatible with this hypothesis. CONCLUSION: This is the first report of POLR1D mutation being responsible for an autosomal recessive inherited Treacher Collins syndrome. These results reinforce the concept of genetic heterogeneity of Treacher Collins syndrome and underline the importance of combining clinical expertise and familial molecular analyses for appropriate genetic counseling.
Authors: Ewan Phillip Ramsay; Guillermo Abascal-Palacios; Julia L Daiß; Helen King; Jerome Gouge; Michael Pilsl; Fabienne Beuron; Edward Morris; Philip Gunkel; Christoph Engel; Alessandro Vannini Journal: Nat Commun Date: 2020-12-17 Impact factor: 14.919