The molecular diagnosis and their detailed clinical presentations in 5 cases of maturity-onset diabetes of the young / 中华实用儿科临床杂志

ABSTRACT

Objective To analyze the genetic changes and detailed clinical presentations of 5 maturity-onset diabetes of the young (MODY) cases in order to enhance the knowledge about MODY in children.Methods Seventy-eight patients initially diagnosed as diabetes mellitus between January 1 and December 31,2015 in Capital Institute of Pediatrics were retrospectively studied.Nine of them were suspected of MODY,and 5 patients were diagnosed as MODY through gene test.Clinical informations were collected including age,gender,main complaint,family history,body mass index (BMI),fasting blood glucose,fasting blood insulin,2-hour blood glucose and insulin after oral glucose tolerance test and glycosylated hemoglobin.The blood glucose was monitored dynamically in 2 patients.Targeted capture panel was designed to capture the 16 genes related to MODY,including 12 genes from MODY1 to MODY13 type and 4 genes with weak evidence of MODY according to Human Gene Mutation Database Exome capture,and Next-Generation sequencing on a HiSeq2000 (Illumina) was performed.After bioinformatics analysis,all prioritized variants detected in patients were validated by Sanger sequencing,including the probands and their parents.Results Five patients were confirmed as MODY by molecular diagnosis,accounting for 6.4％ of all the 78 patients in 2015.The ratio of male to female was 2 ∶ 3.The ages at diagnosis ranged from 2 to 11 years old,and the median age was 3 years old.Two cases were found to have abnormal blood glucose in physical examination.The rest 3 cases were discovered with abnormal blood glucose during hospitalization because of pneumonia (1 case)or diarrhea (2 cases).In 4 cases,their mothers had gestational diabetes history,in 1 case the father suffering from diabetes.BMI ranged 15.68-23.40 kg/m2.Fasting blood glucose was 6.3-7.2 mmol/L.Fasting blood insulin was 0.5-8.0 IU/L.Glucose tolerance test results showed that blood glucose of the patients was 8.6-10.8 mmol/L after 2 hours.The level of glycosylated hemoglobin was 5.5％-6.7％.Blood glucose was 3.9-13.0 mmol/L.All the 5 confirmed patients were caused by GCK gene mutation (MODY2 type).The mutations detected were located at Exon7 (2 cases),Exon4 (1 case),Exon5 (1 case),and Exon10 (1 case).Conclusions All the confirmed MODY patients were identified either through medical exam or infectious disease,and all had positive family history.Their BMI ranged widely.Fasting blood glucose was slightly elevated and glycosylated hemoglobin was normal or slightly elevated,but fasting blood insulin was normal in all the patients.Abnormal glucose tolerance test results were found in all 5 patients.Glycosylated hemoglobin was normal or slightly elevated.MODY2 was the only subtype detected in this group,which indicated that the common type in children was different from that in adults.