The insulin gene variable number of tandemrepeats (INS VNTR) genotype and sleep disordered breathing in childhood obesity

Abstract

Aim of our study is to verify the association between the genetic predisposition to hyperinsulinism due to the presence of the insulin gene (INS) I/I genotype and the development of sleep-related breathing disorders (SRBD) in obese children and adolescents. Two hundred and fifty-six obese children and adolescents (125 girls) have been investigated. As initial screening all subjects' mothers filled out the Sleep Disturbances Scale for Children (SDSC). The Sleep-Disordered Breathing (SDB) scale has been taken into account. Successively, a subgroup of 34 patients belonging to the first (14 children) and the last (20 children) SDB score quintiles underwent an overnight polysomnography and the apnea-hypopnea index (AHI) was evaluated. All subjects were genotyped for the INS VNTR and fasting insulin levels were evaluated. The population was divided into two groups according to the genotype: the first group was comprehensive of patients homozygotes for class I allele and the second group was composed by class III allele heterozygotes and homozygotes patients. Subjects I/I showed statistically signifIcant higher insulin levels (p<0.001) and SDB scores (p<0.001). Moreover, in the subgroup of patients investigated with polysomnography, class I homozygous subjects showed higher AHI compared to those patients carrying class III allele (p<0.001). Our data support the hypothesis that INS VNTR is associated with the development of SDB among obese children and adolescents.