Type 1 diabetes in a Nigerian family - occurrence in three out of four siblings: A case report

BACKGROUND Most occurrences of type 1 diabetes cases in any population are sporadic rather than familial. Hence, type 1 diabetes among siblings is a rare occurrence. Even more rare is for three or more siblings to develop type 1 diabetes. In this report, we describe a case of a Nigerian family in which type 1 diabetes occurred in three siblings among four children with neither parent having diabetes. All three siblings are positive for glutamic acid decarboxylase and anti-islet cell antibodies. CASE SUMMARY There were four siblings (three males and one female) born to a couple without a diagnosis of diabetes. The eldest child (male) was diagnosed with diabetes at the age of 15, the second child (female) was diagnosed at the age of 11 and the fourth child (male) was diagnosed at the age of 9. All the siblings presented with similar osmotic symptoms and were diagnosed of diabetic ketoacidosis. All of them had markedly reduced serum C-peptide levels with high levels of glutamic acid decarboxylase and insulinoma-associated protein-2 antibodies. We could not perform genetic analysis of HLA-DR, DQ and CTLA4 in the siblings as well as the parents; hence haplotypes could not be characterized. Both parents of the probands have no prior history of diabetes, and their blood glucose and glycated hemoglobin levels were within normal ranges. The third child (male) has no history suggestive of diabetes, and his blood glucose and glycated hemoglobin have remained within normal ranges. CONCLUSION Although the occurrence of type 1 diabetes in proband siblings is uncommon, screening for diabetes among siblings especially with islet autoantibodies should be encouraged.