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Case Reports in Genetics
Volume 2011, Article ID 258978, 5 pages
Case Report

Intrafamilial Variability of Early-Onset Diabetes due to an INS Mutation

1Department of Paediatrics, Herlev University Hospital, Ndr Ringvej 75, 2730 Herlev, Denmark
2The Faculty of Health Sciences, University of Copenhagen, Denmark
3Steno Diabetes Center, Niels Steensens Vej 2, 2820 Gentofte, Denmark
4Laboratory of Monogenic Diabetes, Bambino Gesù Children's Hospital, Tor Vergata University Hospital, Viale Oxford, 81 00133 Rome, Italy

Received 19 April 2011; Accepted 9 May 2011

Academic Editors: S.-C. Chae, H. Ishiguro, and V. Shotelersuk

Copyright © 2011 Siri Fredheim et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


Aim. The objective of this study was to describe the clinical characteristics of two siblings and their father carrying a C95Y mutation in the insulin (INS) gene. Methods/Results. A Danish patient, his sister, and his father were identified to carry the C95Y mutation in the preproinsulin molecule causing permanent neonatal diabetes. All three were diagnosed before 29 weeks of age, were born at term with near-normal birth weight, and were negative for GAD, ICA, IA-2, and IAA autoantibodies. The daily insulin requirement the first six months after diagnosis was <0.5 U kg−1 day−1 for both children. The father, insulin treated for over 40 years, has bilateral preproliferative retinopathy. Conclusions. These three cases further confirm the essential features of diabetes caused by INS mutations with proteotoxic effect. We conclude that patients with similar features must be investigated for mutations of INS gene.