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Ks A, Bansal A, Verma PK, Bhat NK. Thurston syndrome with thalassaemia: a rare case devising a novel molecular and phenotypic variation. BMJ Case Rep 2023; 16:e253086. [PMID: 38160027 PMCID: PMC10759122 DOI: 10.1136/bcr-2022-253086] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2024] Open
Abstract
A male infant presented with progressive paleness of the body since 3 months of age. On examination, the child had pallor, microcephaly with dysmorphic facies (depressed nasal bridge, low set ears, retrognathia, high arched palate and tongue hamartoma). Postaxial polydactyly in bilateral hands and feet, broad great toes, with syndactyly of left fourth and fifth toes were present. The haemogram showed severe anaemia with a microcytic hypochromic picture. High-performance liquid chromatography (HPLC) was normal. However, the parents' HPLC was suggestive of beta thalassaemia trait. Whole-exome sequencing revealed Thurston syndrome with beta-thalassaemia in homozygous pattern with a novel mutation. It is a rare genetic syndrome exclusively found in the South Asian population. Due to the rarity, identification of this syndrome is often difficult and requires awareness among clinicians. However, it is important to diagnose the disorder accurately in order to provide appropriate genetic counselling and prognostication to the parents.
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Affiliation(s)
- Aswanth Ks
- Paediatrics, All India Institute of Medical Sciences, Rishikesh, Uttarakhand, India
| | - Adity Bansal
- Dentistry, AIIMS Deoghar, Deoghar, Jharkhand, India
| | - Prashant Kumar Verma
- Paediatrics, All India Institute of Medical Sciences, Rishikesh, Uttarakhand, India
| | - Nowneet Kumar Bhat
- Paediatrics, All India Institute of Medical Sciences, Rishikesh, Uttarakhand, India
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Bruel AL, Ganga AK, Nosková L, Valenzuela I, Martinovic J, Duffourd Y, Zikánová M, Majer F, Kmoch S, Mohler M, Sun J, Sweeney LK, Martínez-Gil N, Thauvin-Robinet C, Breslow DK. Pathogenic RAB34 variants impair primary cilium assembly and cause a novel oral-facial-digital syndrome. Hum Mol Genet 2023; 32:2822-2831. [PMID: 37384395 PMCID: PMC10481091 DOI: 10.1093/hmg/ddad109] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2023] [Revised: 06/12/2023] [Accepted: 06/17/2023] [Indexed: 07/01/2023] Open
Abstract
Oral-facial-digital syndromes (OFDS) are a group of clinically and genetically heterogeneous disorders characterized by defects in the development of the face and oral cavity along with digit anomalies. Pathogenic variants in over 20 genes encoding ciliary proteins have been found to cause OFDS through deleterious structural or functional impacts on primary cilia. We identified by exome sequencing bi-allelic missense variants in a novel disease-causing ciliary gene RAB34 in four individuals from three unrelated families. Affected individuals presented a novel form of OFDS (OFDS-RAB34) accompanied by cardiac, cerebral, skeletal and anorectal defects. RAB34 encodes a member of the Rab GTPase superfamily and was recently identified as a key mediator of ciliary membrane formation. Unlike many genes required for cilium assembly, RAB34 acts selectively in cell types that use the intracellular ciliogenesis pathway, in which nascent cilia begin to form in the cytoplasm. We find that the protein products of these pathogenic variants, which are clustered near the RAB34 C-terminus, exhibit a strong loss of function. Although some variants retain the ability to be recruited to the mother centriole, cells expressing mutant RAB34 exhibit a significant defect in cilium assembly. While many Rab proteins have been previously linked to ciliogenesis, our studies establish RAB34 as the first small GTPase involved in OFDS and reveal the distinct clinical manifestations caused by impairment of intracellular ciliogenesis.
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Affiliation(s)
- Ange-Line Bruel
- INSERM U1231 Génétique des Anomalies du Développement (GAD), University Bourgogne Franche-Comté, 21070 Dijon, France
- Unité Fonctionnelle Innovation en Diagnostic Génomique des Maladies Rares, Fédération Hospitalo-Universitaire Médecine Translationnelle et Anomalies du Développement (FHU-TRANSLAD), Centre Hospitalo-Universitaire (CHU) Dijon Bourgogne, 21079 Dijon, France
| | - Anil Kumar Ganga
- Department of Molecular, Cellular, and Developmental Biology, Yale University, New Haven, CT 06511, USA
| | - Lenka Nosková
- Research Unit for Rare Diseases, Department of Pediatrics and Inherited Metabolic Disorders, First Faculty of Medicine, Charles University and General University Hospital in Prague, Prague 128 08, Czech Republic
| | - Irene Valenzuela
- Department of Clinical and Molecular Genetics, Vall d'Hebron University Hospital, 08035 Barcelona, Spain
- Medical Genetics Group, Vall d'Hebron Research Institute,08035 Barcelona, Spain
| | - Jelena Martinovic
- Unit of Embryo-Fetal Pathology, AP-HP, Antoine Béclère Hospital, Paris Saclay University, 92141 Clamart, France
| | - Yannis Duffourd
- INSERM U1231 Génétique des Anomalies du Développement (GAD), University Bourgogne Franche-Comté, 21070 Dijon, France
- Unité Fonctionnelle Innovation en Diagnostic Génomique des Maladies Rares, Fédération Hospitalo-Universitaire Médecine Translationnelle et Anomalies du Développement (FHU-TRANSLAD), Centre Hospitalo-Universitaire (CHU) Dijon Bourgogne, 21079 Dijon, France
| | - Marie Zikánová
- Research Unit for Rare Diseases, Department of Pediatrics and Inherited Metabolic Disorders, First Faculty of Medicine, Charles University and General University Hospital in Prague, Prague 128 08, Czech Republic
| | - Filip Majer
- Research Unit for Rare Diseases, Department of Pediatrics and Inherited Metabolic Disorders, First Faculty of Medicine, Charles University and General University Hospital in Prague, Prague 128 08, Czech Republic
| | - Stanislav Kmoch
- Research Unit for Rare Diseases, Department of Pediatrics and Inherited Metabolic Disorders, First Faculty of Medicine, Charles University and General University Hospital in Prague, Prague 128 08, Czech Republic
| | - Markéta Mohler
- Institute of Molecular and Clinical Pathology and Medical Genetics, University Hospital Ostrava, Ostrava 708 52, Czech Republic
| | - Jingbo Sun
- Department of Molecular, Cellular, and Developmental Biology, Yale University, New Haven, CT 06511, USA
| | - Lauren K Sweeney
- Department of Molecular, Cellular, and Developmental Biology, Yale University, New Haven, CT 06511, USA
| | - Núria Martínez-Gil
- Department of Clinical and Molecular Genetics, Vall d'Hebron University Hospital, 08035 Barcelona, Spain
- Medical Genetics Group, Vall d'Hebron Research Institute,08035 Barcelona, Spain
| | - Christel Thauvin-Robinet
- INSERM U1231 Génétique des Anomalies du Développement (GAD), University Bourgogne Franche-Comté, 21070 Dijon, France
- Unité Fonctionnelle Innovation en Diagnostic Génomique des Maladies Rares, Fédération Hospitalo-Universitaire Médecine Translationnelle et Anomalies du Développement (FHU-TRANSLAD), Centre Hospitalo-Universitaire (CHU) Dijon Bourgogne, 21079 Dijon, France
- Centre de Génétique et Centre de référence maladies rares ‘Anomalies du Développement et Syndromes Malformatifs’, FHU-TRANSLAD, Hôpital d'Enfants, CHU Dijon Bourgogne, 21079 Dijon, France
| | - David K Breslow
- Department of Molecular, Cellular, and Developmental Biology, Yale University, New Haven, CT 06511, USA
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