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Raffan E, Soos MA, Rocha N, Tuthill A, Thomsen AR, Hyden CS, Gregory JW, Hindmarsh P, Dattani M, Cochran E, Al Kaabi J, Gorden P, Barroso I, Morling N, O’Rahilly S, Semple RK. Founder effect in the Horn of Africa for an insulin receptor mutation that may impair receptor recycling. Diabetologia 2011; 54:1057-65. [PMID: 21318406 PMCID: PMC3071941 DOI: 10.1007/s00125-011-2066-z] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/20/2010] [Accepted: 01/07/2011] [Indexed: 11/26/2022]
Abstract
AIMS/HYPOTHESIS Genetic insulin receptoropathies are a rare cause of severe insulin resistance. We identified the Ile119Met missense mutation in the insulin receptor INSR gene, previously reported in a Yemeni kindred, in four unrelated patients with Somali ancestry. We aimed to investigate a possible genetic founder effect, and to study the mechanism of loss of function of the mutant receptor. METHODS Biochemical profiling and DNA haplotype analysis of affected patients were performed. Insulin receptor expression in lymphoblastoid cells from a homozygous p.Ile119Met INSR patient, and in cells heterologously expressing the mutant receptor, was examined. Insulin binding, insulin-stimulated receptor autophosphorylation, and cooperativity and pH dependency of insulin dissociation were also assessed. RESULTS All patients had biochemical profiles pathognomonic of insulin receptoropathy, while haplotype analysis revealed the putative shared region around the INSR mutant to be no larger than 28 kb. An increased insulin proreceptor to β subunit ratio was seen in patient-derived cells. Steady state insulin binding and insulin-stimulated autophosphorylation of the mutant receptor was normal; however it exhibited decreased insulin dissociation rates with preserved cooperativity, a difference accentuated at low pH. CONCLUSIONS/INTERPRETATION The p.Ile119Met INSR appears to have arisen around the Horn of Africa, and should be sought first in severely insulin resistant patients with ancestry from this region. Despite collectively compelling genetic, clinical and biochemical evidence for its pathogenicity, loss of function in conventional in vitro assays is subtle, suggesting mildly impaired receptor recycling only.
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Affiliation(s)
- E. Raffan
- University of Cambridge Metabolic Research Laboratories, Institute of Metabolic Science, University of Cambridge, Addenbrooke’s Hospital B289, Cambridge, CB2 0QR UK
| | - M. A. Soos
- University of Cambridge Metabolic Research Laboratories, Institute of Metabolic Science, University of Cambridge, Addenbrooke’s Hospital B289, Cambridge, CB2 0QR UK
| | - N. Rocha
- University of Cambridge Metabolic Research Laboratories, Institute of Metabolic Science, University of Cambridge, Addenbrooke’s Hospital B289, Cambridge, CB2 0QR UK
| | - A. Tuthill
- University of Cambridge Metabolic Research Laboratories, Institute of Metabolic Science, University of Cambridge, Addenbrooke’s Hospital B289, Cambridge, CB2 0QR UK
| | - A. R. Thomsen
- Section of Forensic Genetics, Department of Forensic Medicine, Faculty of Health Sciences, University of Copenhagen, Copenhagen, Denmark
| | - C. S. Hyden
- University of Cambridge Metabolic Research Laboratories, Institute of Metabolic Science, University of Cambridge, Addenbrooke’s Hospital B289, Cambridge, CB2 0QR UK
| | - J. W. Gregory
- Department of Child Health, Wales School of Medicine, Cardiff University, Cardiff, UK
| | - P. Hindmarsh
- Institute of Child Health, University College London, London, UK
| | - M. Dattani
- Institute of Child Health, University College London, London, UK
| | - E. Cochran
- Clinical Endocrinology Branch, National Institute of Diabetes, Digestive and Kidney Diseases, Bethesda, MD USA
| | - J. Al Kaabi
- Faculty of Medicine and Health Sciences, United Arab Emirates University, Al-Ain, United Arab Emirates
| | - P. Gorden
- Clinical Endocrinology Branch, National Institute of Diabetes, Digestive and Kidney Diseases, Bethesda, MD USA
| | - I. Barroso
- University of Cambridge Metabolic Research Laboratories, Institute of Metabolic Science, University of Cambridge, Addenbrooke’s Hospital B289, Cambridge, CB2 0QR UK
- The Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Cambridge, UK
| | - N. Morling
- Section of Forensic Genetics, Department of Forensic Medicine, Faculty of Health Sciences, University of Copenhagen, Copenhagen, Denmark
| | - S. O’Rahilly
- University of Cambridge Metabolic Research Laboratories, Institute of Metabolic Science, University of Cambridge, Addenbrooke’s Hospital B289, Cambridge, CB2 0QR UK
| | - R. K. Semple
- University of Cambridge Metabolic Research Laboratories, Institute of Metabolic Science, University of Cambridge, Addenbrooke’s Hospital B289, Cambridge, CB2 0QR UK
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