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Koneshamoorthy A, Seniveratne-Epa D, Calder G, Sawyer M, Kay TWH, Farrell S, Loudovaris T, Mariana L, McCarthy D, Lyu R, Liu X, Thorn P, Tong J, Chin LK, Zacharin M, Trainer A, Taylor S, MacIsaac RJ, Sachithanandan N, Thomas HE, Krishnamurthy B. Case Report: Hypoglycemia Due to a Novel Activating Glucokinase Variant in an Adult - a Molecular Approach. Front Endocrinol (Lausanne) 2022; 13:842937. [PMID: 35370948 PMCID: PMC8969599 DOI: 10.3389/fendo.2022.842937] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/24/2021] [Accepted: 02/17/2022] [Indexed: 11/13/2022] Open
Abstract
We present a case of an obese 22-year-old man with activating GCK variant who had neonatal hypoglycemia, re-emerging with hypoglycemia later in life. We investigated him for asymptomatic hypoglycemia with a family history of hypoglycemia. Genetic testing yielded a novel GCK missense class 3 variant that was subsequently found in his mother, sister and nephew and reclassified as a class 4 likely pathogenic variant. Glucokinase enables phosphorylation of glucose, the rate-limiting step of glycolysis in the liver and pancreatic β cells. It plays a crucial role in the regulation of insulin secretion. Inactivating variants in GCK cause hyperglycemia and activating variants cause hypoglycemia. Spleen-preserving distal pancreatectomy revealed diffuse hyperplastic islets, nuclear pleomorphism and periductular islets. Glucose stimulated insulin secretion revealed increased insulin secretion in response to glucose. Cytoplasmic calcium, which triggers exocytosis of insulin-containing granules, revealed normal basal but increased glucose-stimulated level. Unbiased gene expression analysis using 10X single cell sequencing revealed upregulated INS and CKB genes and downregulated DLK1 and NPY genes in β-cells. Further studies are required to see if alteration in expression of these genes plays a role in the metabolic and histological phenotype associated with glucokinase pathogenic variant. There were more large islets in the patient's pancreas than in control subjects but there was no difference in the proportion of β cells in the islets. His hypoglycemia was persistent after pancreatectomy, was refractory to diazoxide and improved with pasireotide. This case highlights the variable phenotype of GCK mutations. In-depth molecular analyses in the islets have revealed possible mechanisms for hyperplastic islets and insulin hypersecretion.
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Affiliation(s)
- Anojian Koneshamoorthy
- Department of Endocrinology and Diabetes, St. Vincent’s Hospital, Melbourne, VIC, Australia
| | - Dilan Seniveratne-Epa
- Department of Endocrinology and Diabetes, St. Vincent’s Hospital, Melbourne, VIC, Australia
| | - Genevieve Calder
- Department of Endocrinology and Diabetes, St. Vincent’s Hospital, Melbourne, VIC, Australia
| | - Matthew Sawyer
- Department of Endocrinology and Diabetes, St. Vincent’s Hospital, Melbourne, VIC, Australia
| | - Thomas W. H. Kay
- Department of Endocrinology and Diabetes, St. Vincent’s Hospital, Melbourne, VIC, Australia
- St. Vincent’s Institute of Medical Research, Melbourne, VIC, Australia
- Department of Medicine, St. Vincent’s Hospital, Melbourne, VIC, Australia
| | - Stephen Farrell
- Department of Surgery, St. Vincent’s Hospital, Melbourne, VIC, Australia
| | - Thomas Loudovaris
- St. Vincent’s Institute of Medical Research, Melbourne, VIC, Australia
| | - Lina Mariana
- St. Vincent’s Institute of Medical Research, Melbourne, VIC, Australia
| | - Davis McCarthy
- St. Vincent’s Institute of Medical Research, Melbourne, VIC, Australia
- Melbourne Integrative Genomics, Faculty of Science, University of Melbourne, Melbourne, VIC, Australia
| | - Ruqian Lyu
- St. Vincent’s Institute of Medical Research, Melbourne, VIC, Australia
| | - Xin Liu
- St. Vincent’s Institute of Medical Research, Melbourne, VIC, Australia
- Melbourne Integrative Genomics, Faculty of Science, University of Melbourne, Melbourne, VIC, Australia
| | - Peter Thorn
- Charles Perkins Centre, School of Medical Sciences, University of Sydney, Sydney, NSW, Australia
| | - Jason Tong
- Charles Perkins Centre, School of Medical Sciences, University of Sydney, Sydney, NSW, Australia
| | - Lit Kim Chin
- Department of Diabetes and Endocrinology, Royal Children’s Hospital, Melbourne, VIC, Australia
| | - Margaret Zacharin
- Department of Diabetes and Endocrinology, Royal Children’s Hospital, Melbourne, VIC, Australia
| | - Alison Trainer
- Department of Genomic Medicine, Royal Melbourne Hospital, Melbourne, VIC, Australia
| | - Shelby Taylor
- Department of Genomic Medicine, Royal Melbourne Hospital, Melbourne, VIC, Australia
| | - Richard J. MacIsaac
- Department of Endocrinology and Diabetes, St. Vincent’s Hospital, Melbourne, VIC, Australia
- Department of Medicine, St. Vincent’s Hospital, Melbourne, VIC, Australia
| | - Nirupa Sachithanandan
- Department of Endocrinology and Diabetes, St. Vincent’s Hospital, Melbourne, VIC, Australia
- Department of Medicine, St. Vincent’s Hospital, Melbourne, VIC, Australia
| | - Helen E. Thomas
- St. Vincent’s Institute of Medical Research, Melbourne, VIC, Australia
- Department of Medicine, St. Vincent’s Hospital, Melbourne, VIC, Australia
| | - Balasubramanian Krishnamurthy
- Department of Endocrinology and Diabetes, St. Vincent’s Hospital, Melbourne, VIC, Australia
- St. Vincent’s Institute of Medical Research, Melbourne, VIC, Australia
- Department of Medicine, St. Vincent’s Hospital, Melbourne, VIC, Australia
- *Correspondence: Balasubramanian Krishnamurthy,
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