Oral glucose tolerance and insulin release test in 52 cases of obese and overweight children / 中华儿科杂志

<p><b>OBJECTIVE</b>To assess the state of glucose metabolism and beta-cell function in obese and overweight children.</p><p><b>METHODS</b>Levels of glucose and insulin were detected during oral glucose tolerance test in 52 obese and overweight children aged 11.3 +/- 1.8 years with body mass index (BMI) 30.2 +/- 19.2 kg/m(2). Insulin resistance index (IR = FIN x FPG/22.5), insulin sensitivity index (IS = 1/FIN x FPG) and ratio of insulin increment to glucose increment at 30' (I(30)-I(0)/G(30)-G(0)) post oral glucose were measured. (FIN = fasting insulin. FPG = fasting plasma glucose). The IR, IS and the ratio post oral glucose were compared among groups with varying BMI and between groups of impaired glucose tolerance (IGT) and control. Serum triglyceride determination and B ultrasonography of liver were performed.</p><p><b>RESULTS</b>(1) one patient with type 2 diabetes (1.9%) and 5 patients with IGT (9.6%) were found. (2) IR (> or = 2.8) was observed in 76.9% of the cases. (3) The IR, IS and their ratio showed no difference between the compared groups. (4) IR and IS did not show significant difference but there was significant difference in ratio between the IGT and control group. (5) Increased serum triglyceride and fatty liver were noted in 36.5% and 53.3% of the cases, respectively.</p><p><b>CONCLUSION</b>The results indicated that insulin resistance and reduced insulin sensitivity in obese and overweight children are common, and these changes seemed not to correlated with the varying degree of BMI. Beta-cells function was obviously impaired in obese children with IGT and disorder of lipid metabolism exists in many obese and overweight children revealed.</p>

Prader-Willi syndrome and genomic imprinting / 中华儿科杂志

<p><b>OBJECTIVE</b>Prader-Willi syndrome (PWS) is an example of a human genetic disorder that involves imprinting genes on the proximal long arm of chromosome 15 and SNRPN gene as a candidate gene for this syndrome. The purpose of this study was to show the molecular genetic defects and genomic imprinting basis in Chinese PWS patients and to evaluate the clinical applications of a differential diagnostic test for PWS.</p><p><b>METHODS</b>Fluorescence in situ hybridization (FISH) and methylation-specific PCR (MSPCR) techniques were applied for 4 clinically suspected PWS patients. Using three probes, including SNRPN probe for identification of the critical locus in PWS region, D15Z1 and PML control probes for identification of the 15p arm and 15q arm, the authors detected the deletions 15q in PWS. MSPCR was based on sodium bisulfite treatment of DNA and PCR primers specific for the maternal and paternal allele.</p><p><b>RESULTS</b>When hybridized with mixed probes, it was found in 2 patients that the central specific signal was absent, but both the flanking control signals were retained, indicating SNRPN gene deletion of chromosome 15q11-13. Bisulfite-modified DNA from all PWS children amplified with methylated allele-specific primer pair showed only maternal 131bp PCR product, indicating the maternal uniparental disomy (UPD15).</p><p><b>CONCLUSION</b>Genomic imprinting plays an important role in the molecular pathogenesis of PWS that caused by paternal microdeletions of 15q11-q13 or maternal UPD of chromosome 15. The basic defect seemed to be an absence of function of PWS genes that are normally expressed only from the paternal chromosome 15. MSPCR is a rapid and simple PCR-based assay compared with other cyto-molecular tests and its results were consistent with the clinical diagnosis of PWS, so it seems to be a reliable diagnostic method for PWS patients who show abnormal methylation at SNRPN. The genetic differential tests for PWS are important in determining familial recurrence risk.</p>