Disorder Of The Growth Hormone/insulin-like Growth Factors(GH/IGFs) Axis In Children With Idiopathic Short Stature

【Background】Idiopathic short stature(ISS) is a term used forchildren in whom the pathogenesis or aetiology of the short stature isundefined.The growth hormone (GH)-insulin-like growth factor-1(IGF-1)axis plays such a key role in regulating growth and development thatpeople try to elucidate the relationship between the disturbance of thehormone, growth factors and signaling pathway in this endocritic axis andidiopathic short stature. However, the data in this field beingheterogeneous and sometimes contradictory, further studies are necessary.Previous reports have suggested that there was growth hormoneinsensitivity in children with idiopathic short stature and growth hormonereceptor(GHR) mutations in children with idiopathic short stature werealso reported by authors abroad.【Objective】To evaluate whether children with ISS had reducedconcentration of serum IGF-1 and IGFBP-3, whether the decreased levelsof serum IGF-1 and IGFBP-3 result from growth hormone insensitivitycaused by deficiency of GHR,which correspond with levels of serumGHBP.To determine whether children with idiopathic short stature inHunan china had growth hormone receptor mutations,and to elucidate the aetiology of idiopathic short stature, and to provide theoretic evidence fortreatment to idiopathic short stature. To research the personality andbehavior of boys with idiopathic short stature(ISS) and to determine theeffects of short stature on personality and behavior.【Methods】Thirty-seven children with idiopathic short stature and 37age- and sex-matched normal- statured children were included in the study.The serum basal GH was measeured by specific radioimmunoassay, theserum IGF-1, IGFBP-3 were measeured by immunoradiometric analysisand GHBP was measured by Dextran-coated charcoal technique. Codingsequences and intron-exon boundaries of exons 2-7 of growth hormonereceptor gene in thirty-seven children with idiopathic short stature wereamplified by PCR and subsequently analyzed through single-strandconformation(SSCP) analysis to scan for mutation.Mutations deteced asaberrant bands by analysis of single-strand conformation polymorphismswere confirmed by sequencing the PCR products, or PCR products oftweleve patients with more severe short stature were sequenced thoughtheir PCR products showed no abnormal migration of SSCP analysis.Thirty-two boys with idiopathic short stature and 32 cases of age-matchednormal- statured boys were investigated for personality by using Eysenkpersonality questionnaire (EPQ) inventory and for behavior problem byusing Child Behavior Check-list (CBCL).【Results】1.In comparison to normal subjects, ISS subjects had significantly lower serum values for GHBP, IGF-Ⅰ, IGFBP-3 (P＜0.01),however ISS subjects had higher serum basal GH than normal controls(P＜0.05).2.In the ISS group, there were significant positive correlationbetween GHBP and age(r=0.386, P＜0.02), height(r=0.485, P=0.002),weight (r=0.508, P=0.001), and IGF-1 (r=0.379, P=0.02); in the controlgroup, there were significant positive correlation between GHBP andage(r=0.780, P＜0.001), height(r=0.849, P＜0.000), weight (r=0.833,P＜0.001), and IGF-1 (r=0.673, P＜0.001). 3. In the ISS group, significantpositive correlations between IGF-1 and IGFBP-3(r=0.863, P＜0.001),age(r=0.928, P＜0.001), height(r=0.909, P＜0.001), and weight (r=0.887,P＜0.001) were found; in the control group, significant positive correlationsbetween IGF-1 and IGFBP-3(r=0.861, P＜0.001), age(r=0.788, P＜0.001),height(r=0.827, P＜0.001), and weight(r=0.804, P＜0.001) were found. 4.In the ISS group, there were significant positive correlation betweenIGFBP-3 and GHBP(r=0.423, P＜0.02), age(r=0.837, P＜0.001), height(r=0.786, P＜0.001), weight(r=0.811, P＜0.001); in the control group, therewere significant positive correlation between IGFBP-3 and GHBP(r=0.562,P＜0.001),age(r=0.660,P＜0.001), height(r=0.697,P＜0.001), weight (r=0.670,P＜0.001). 5.All the PCR fragment of individual exons of the GHR geneexcept for exon 3 were clear, bright and of the predicted sizes on 1.5％agarose gel electrophoresis. 6.The single-strand conformationpolymorphisms analysis of the GHR gene show no abnormal migration in all patients. 7.We further sequenced exon 2, exon 4～7 in twelve patientswith more severe short stature.A homozygous A to G transition (AGT toGGT) in first position of codon 16 of signal peptide in exon 2 was found inpatient 22,which results in an amino acid change (Ser16Gly, S16G).Thismutation was not found in thirty-seven control subjects, not supporting it isa polymorphism,which may be a novel GHR gene mutation. 8. Aheterozygous G to A transition (CGA to CAA) in second position of codon43 of exon 4 was found in eight patients and in one normal subject, whichresults in an amino acid change (Arg43Gln,R43Q),concordant withpolymorphic changes,which is a novel GHR gene polymorphism. 9. Ahomozygous A to G transition (GGA to GGG) in third position of codon168 of exon 6 was found in five patients and in one normal subject, withno amino acid change, concordant with known polymorphic changes. 10.InISS group, the score of E inventory was lower while the score of Ninventory was higher than those in control group(P＜0.01). As determinedfrom CBCL, boys with ISS had lower activities and social competencethan those in control group (P＜0.02, P＜0.01),while no significantdifference in school aspect between ISS group and control group. Therewas no significant difference in total behavior problems raw scores andmost subscales between ISS group and control group with exception thatsignificantly difference in withdrawn and poor communication were found.【Conclusions】1.Reduced concentration of serum IGF-1 and IGFBP-3 may be one of the causes that contribute to growth failure inchildren with ISS. 2.The decreased levels of serum GHBP, but elevatedbasal GH in children with ISS suggest that these children could have agrowth hormone insensitivity resulting from GHR deficiency. 3.Ahomozygous A to G transition (AGT to GGT) in first position of codon16 of signal peptide in exon 2 was found in patient 22, which results in anamino acid change (Ser16Gly, S16G), which may be a novel GHR genemutation. 4.A heterozygous G to A transition(CGA to CAA) in secondposition of codon 43 of exon 4 was found, which results in an amino acidchange(Arg43Gln,R43Q), concordant with polymorphic changes, which isa novel GHR gene polymorphism. 5.Boys with ISS show a tendencytowards introversion and emotional liability. They have lower activitiesand social competence and behavior problems in withdrawn and poorcommunication.