Monogenic diabetes in Pakistani infants and children: challenges in a resource poor country.

OBJECTIVES To review the data of infants and children with suspected monogenic diabetes who underwent genetic testing. METHODS Monogenic diabetes is a rare form of diabetes resulting from mutations in a single gene. It can be caused by dominant as well as recessive modes of inheritance. In a country like Pakistan where interfamily marriages are common the incidence of genetic disorders is increased. As Pakistan a resource-poor country, the diagnosis of insulin-dependent diabetes is often delayed and a genetic diagnosis of monogenic diabetes is extremely difficult. Children with clinical diagnosis of monogenic and syndromic diabates were recruited and blood samples were sent for genetic analysis. RESULTS One thousand sixty four new cases diagnosed with type 1 diabetes were registered at the National Institute of Child Health, Karachi, in the last 10 years. Of these 39 patients were selected for genetic testing who were diagnosed with diabetes/had a sibling diagnosed with diabetes before the age of nine months (n = 27) or had extra pancreatic features ( n= 12). We identified mutations in 18/27 cases diagnosed with diabetes before nine months of age. The most common genetic subtype was WolcottRallison syndrome caused by EIF2AK3 mutations (seven cases). KCNJ11 mutations were identified in two cases, ABCC8mutations were identified in four cases from three families, GCK and INS mutations were each identified in two cases, and one SLC2A2 mutation was identified in one case. A genetic diagnosis was made in 12/12 children from six families with diabetes diagnosed after the age of nine months who had extrapancreatic features. Six patients had genetically confirmed Wolfram syndrome (WFS1), three had thiamine-responsive megaloblastic anemia (SLC19A2) and three were diagnosed with histocytosis lymphadenopathy plus syndrome (SLC29A3). CONCLUSIONS Genetic testing is essential to confirm a diagnosis of monogenic diabetes which guides clinical management and future counselling. Our study highlights the importance of diagnosing monogenic diabetes in the largely consanguineously-married population of Pakistan.