Growth Hormone Receptor Exon Research Articles

Characterization of dominant-negative growth hormone receptor variants reveals a potential therapeutic target for short stature.

Growth hormone insensitivity (GHI) encompasses growth restriction, normal/elevated growth hormone (GH), and low insulin-like growth factor I (IGF1). "Nonclassical" GHI is poorly characterized and is rarely caused by heterozygous dominant-negative (DN) variants located in the intracellular or transmembrane domains of the GH receptor (GHR). We sought to determine the molecular mechanisms underpinning the growth restriction in 2 GHI cases. A custom-made genetic investigative pipeline was exploited to identify the genetic cause of growth restriction in patients with GHI. Nanoluc binary technology (NanoBiT), in vitro splicing assays, western blotting, and flow cytometry, characterized the novel GHR variants. Novel heterozygous GHR variants were identified in 2 unrelated patients with GHI. In vitro splicing assays indicated both variants activated the same alternative splice acceptor site resulting in aberrant splicing and exclusion of 26 base pairs of GHR exon 9. The GHR variants produced truncated receptors and impaired GH-induced GHR signaling. NanoBiT complementation and flow cytometry showed increased cell surface expression of variant GHR homo/heterodimers compared to wild-type (WT) homodimers and increased recombinant human GH binding to variant GHR homo/heterodimers and GH binding protein (GHBP) cleaved from the variant GHRs. The findings demonstrated increased variant GHR dimers and GHBP with resultant GH sequestration. We identified and characterized 2 novel, naturally occurring truncated GHR gene variants. Intriguingly, these DN GHR variants act via the same cryptic splice acceptor site, highlighting impairing GH binding to excess GHBP as a potential therapeutic approach.

GH Receptor Exon 3 Genotype and Echocardiographic Abnormalities in Patients With Active Acromegaly

Background: The GH receptor (GHR) exon 3 polymorphism occurs at a genomic level. Approximately 50-60% of the population is homozygous for the exon-3 containing genotype (+3/+3), 30-40% are heterozygous (+3/-3) and 10-20% are homozygous for the exon-3 lacking genotype (-3/-3). Some studies suggest that children homo- and heterozygous for the GHR exon 3 lacking genotype (-more efficient 3/-3 and +3/-3, respectively) respond better to treatment with exogenous rhGH and there is also in vitro evidence showing a more efficient signal transduction through this exon 3 deleted isoform. Some studies have found that patients with acromegaly harboring the exon 3-deleted genotype may have a higher prevalence of diabetes and hypertension. Hypothesis and Objective: Patients with active acromegaly harboring the exon 3-lacking GHR genotype may have more echocardiographic abnormalities than those who are homozygous for the exon 3 containing genotype. Patients and Methods: This is a cross-sectional study of patients with active acromegaly, defined by an IGF-1 level > 1.3 times the upper limit of normal (x ULN), who underwent transthoracic echocardiography. Exon-3 GHR genotype was determined by PCR using previously described sense and antisense primers. Results: The cohort consisted of 28 patients, 54% female, with a mean age of 51 ± 12 years. Mean disease duration at the time of echocardiographic examination was 4.48 ± 4.7 years; median basal GH and IGF-1 were 12 ± 26 ng/mL and 2.4 ± 1.04 x ULN. The prevalence of hypertension and diabetes were 43% and 36%, respectively. Fifty three percent of the patients were homozygous for the exon 3-containaing genotype (+3/+3), 18% were homozygous for the exon 3-lacking genotype (-3/-3) and 29% were heterozygous (+3/-3). Clinical and biochemical features did not differ between patients with the different GHR genotypes, except for hypertension that was more prevalent in the +3/+3 genotype group (60% vs 23%, p= 0.04). The frequency of the different echocardiographic parameters was similar among groups (left ventricular hypertrophy 33% vs 15%, p= 0.27; diastolic dysfunction 47% vs 31%, p= 0.39; subclinical systolic dysfunction 42% vs 54%, p= 0.54; left ventricular ejection fraction 59±10% vs 60±16%, p= 0.83); aortic valve abnormalities 19% vs 15%, p=0.63; mitral valve abnormalities 46% vs 15%, p=0.07). Conclusions: Echocardiographic abnormalities in patients with active acromegaly do not differ among patients with the different GHR exon 3 genotypes. The clinical spectrum of acromegaly varies considerably. Although such variability is usually related to the severity of the hypersomatotropinemia, in many patients this is not the case.

Growth Hormone insensitivity (Laron syndrome): Report of a new family and review of Brazilian patients.

Laron’s syndrome (LS) is a rare genetic disorder characterized by insensitivity to growth hormone (GH). Up to the present time, over 70 mutations of GH receptor (GHR) gene have been identified leading to GH/insulin-like growth factor type 1 (IGF1) signaling pathway defect. The number of LS patients worldwide is unknown, as many are probably undiagnosed. We report two sibs from a consanguineous family from Minas Gerais, southeastern Brazil. The parents have three children. The older, a 4-years-old girl was 80.2 cm tall (-5.7 SDS height/age), and the youngest sister, aged 3 years, was 73.2 cm tall (-5.82 SDS height/age). Their clinical and biochemical features are typical of LS patients, such as high serum level of GH and low IGF1 concentrations. A homozygous c.1A>T nucleotide substitution in GHR exon 2 in the probands’ samples was identified. Their parents and healthy sister are heterozygous for the same variant that abolishes the translation initiation codon of GHR. This mutation has not been reported in Brazilian patients and was previously associated with an LS phenotype in a single 29-year-old Spanish man. In addition to this case report, we summarize the main characteristics and molecular data of the 21 LS Brazilian patients who have been published to date.

Analysis of the influencing factors of recombinant human growth hormone effect in the children with Turner syndrome

Objective: To analyze the clinical data, karyotype, growth hormone receptor (GHR) exon 3 polymorphism, etc. in Turner syndrome before and after recombinant human growth hormone (rhGH) treatment, and thereby to understand the related factors influencing the rhGH curative effect in children with Turner syndrome. Methods: This was a retrospective study of 31 cases with Turner syndrome who were treated with growth hormone for more than 1 year in the pediatric outpatient department of Tongji Hospital Affiliated to Tongji Medical College, Huazhong University of Science and Technology from January 2010 to January 2017. The GHR Exon3 polymorphism was detected by PCR assay, Turner syndrome children were divided according to GHR exon3 genotype for homozygous for the full-length GHR isoform (fl/fl-GHR)and carriers of one or two copies of the GHR exon3 allele(fl/d3-GHR;d3/d3-GHR).According to the karyotype, the children were divided into 45,X karyotype group and other karyotype group. The height standard deviation (Ht-SDS) and growth velocity (GV) as indicators to measure rhGH treatment efficacy, the data were analyzed by the SPSS12.0 software (t test, one-way ANOVA and multiple linear regression analysis). Results: (1) The mean age at diagnosis of 31 cases was (12.2±2.9) years, the bone age was (8.9±2.4) years, the height was (126.2±10.5) cm and the Ht-SDS was (-3.5±1.3) SDS. The karyotype was 45,X in 14 patients, 17 cases had other karyotypes. Thirteen cases were of (fl/fl-GHR) (42%), 14 cases of fl/d3-GHR (45%) and 4 cases of d3/d3-GHR(13%).Among the 31 cases, the main reason for 5 patients' hospitalization was no secondary sexual characteristics, another 26 cases had short stature (accounting for 81%).(2) After Growth hormone treatment, growth rate (cm/year)(7.3±1.4, 7.0±3.0, 7.0±1.3) and Ht-SDS (-2.8±1.2, -2.5±0.9, -2.2±0.8) were significantly higher than the pre-treatment levels (2.9±0.9, -3.5±1.3), the difference was statistically significant (F=54.12, 4.43, P<0.05) ; the third year Ht-SDS(-2.2±0.8)higher than the first year Ht-SDS(-2.8±1.2), the difference was statistically significant (t=-2.3, P<0.05) .(3)Before rhGH treatment, the height of 45,X karyotype group was significantly lower than that of other karyotypes ((122.1±9.1) cm vs. (129.9±10.3) cm, t=-2.2, P<0.05)). Before and after rhGH treatment, there was no significant difference in growth rate (cm/year) and Ht-SDS, between 45, X karyotype group and other karyotype group, but with the prolongation of treatment time, the Ht-SDS of other karyotype groups had an improvement trend compared with the 45,X karyotype groups. (4) After short-term and long-term treatment with rhGH, there were no significant differences in GV, Ht-SDS between patients with different genotypes (P>0.05). (5) Multivariate linear regression analysis showed that ΔHt-SDS was negatively correlated with the age at initial treatment(partial regression coefficient=-0.098, P <0.05), and positively correlated with GV before treatment(partial regression coefficient=0.202, P<0.05). Conclusions: In Turner's syndrome children, the earlier the rhGH treatment started, the faster the growth rate before treatment and the longer treatment duration, the better effect of rhGH treatment was obtained. Before rhGH treatment, the height of 45,X karyotype group was significantly lower than that of other karyotypes. Before and after rhGH treatment, there was no significant difference in growth rate (cm/year) and Ht-SDS, but with the prolongation of treatment time, the Ht-SDS of other karyotype groups had an improvement trend compared with the 45,X karyotype groups. GHR exon 3 polymorphism did not significantly affect the efficacy of rhGH in Turner syndrome children, but large-scale long-term studies are still needed.

Growth hormone receptor-deficient pigs resemble the pathophysiology of human Laron syndrome and reveal altered activation of signaling cascades in the liver

ObjectiveLaron syndrome (LS) is a rare, autosomal recessive disorder in humans caused by loss-of-function mutations of the growth hormone receptor (GHR) gene. To establish a large animal model for LS, pigs with GHR knockout (KO) mutations were generated and characterized. MethodsCRISPR/Cas9 technology was applied to mutate exon 3 of the GHR gene in porcine zygotes. Two heterozygous founder sows with a 1-bp or 7-bp insertion in GHR exon 3 were obtained, and their heterozygous F1 offspring were intercrossed to produce GHR-KO, heterozygous GHR mutant, and wild-type pigs. Since the latter two groups were not significantly different in any parameter investigated, they were pooled as the GHR expressing control group. The characterization program included body and organ growth, body composition, endocrine and clinical-chemical parameters, as well as signaling studies in liver tissue. ResultsGHR-KO pigs lacked GHR and had markedly reduced serum insulin-like growth factor 1 (IGF1) levels and reduced IGF-binding protein 3 (IGFBP3) activity but increased IGFBP2 levels. Serum GH concentrations were significantly elevated compared with control pigs. GHR-KO pigs had a normal birth weight. Growth retardation became significant at the age of five weeks. At the age of six months, the body weight of GHR-KO pigs was reduced by 60% compared with controls. Most organ weights of GHR-KO pigs were reduced proportionally to body weight. However, the weights of liver, kidneys, and heart were disproportionately reduced, while the relative brain weight was almost doubled. GHR-KO pigs had a markedly increased percentage of total body fat relative to body weight and displayed transient juvenile hypoglycemia along with decreased serum triglyceride and cholesterol levels. Analysis of insulin receptor related signaling in the liver of adult fasted pigs revealed increased phosphorylation of IRS1 and PI3K. In agreement with the loss of GHR, phosphorylation of STAT5 was significantly reduced. In contrast, phosphorylation of JAK2 was significantly increased, possibly due to the increased serum leptin levels and increased hepatic leptin receptor expression and activation in GHR-KO pigs. In addition, increased mTOR phosphorylation was observed in GHR-KO liver samples, and phosphorylation studies of downstream substrates suggested the activation of mainly mTOR complex 2. ConclusionGHR-KO pigs resemble the pathophysiology of LS and are an interesting model for mechanistic studies and treatment trials.

Generation of GHR-modified pigs as Laron syndrome models via a dual-sgRNAs/Cas9 system and somatic cell nuclear transfer

BackgroundLaron syndrome is an autosomal disease resulting from mutations in the growth hormone receptor (GHR) gene. The only therapeutic treatment for Laron syndrome is recombinant insulin-like growth factor I (IGF-I), which has been shown to have various side effects. The improved Laron syndrome models are important for better understanding the pathogenesis of the disease and developing corresponding therapeutics. Pigs have become attractive biomedical models for human condition due to similarities in anatomy, physiology, and metabolism relative to humans, which could serve as an appropriate model for Laron syndrome.MethodsTo further improve the GHR knockout (GHRKO) efficiency and explore the feasibility of precise DNA deletion at targeted sites, the dual-sgRNAs/Cas9 system was designed to target GHR exon 3 in pig fetal fibroblasts (PFFs). The vectors encoding sgRNAs and Cas9 were co-transfected into PFFs by electroporation and GHRKO cell lines were established by single cell cloning culture. Two biallelic knockout cell lines were selected as the donor cell line for somatic cell nuclear transfer for the generation of GHRKO pigs. The genotype of colonies, cloned fetuses and piglets were identified by T7 endonuclease I (T7ENI) assay and sequencing. The GHR expression in the fibroblasts and piglets was analyzed by confocal microscopy, quantitative polymerase chain reaction (q-PCR), western blotting (WB) and immunohistochemical (IHC) staining. The phenotype of GHRKO pigs was recapitulated through level detection of IGF-I and glucose, and measurement of body weight and body size. GHRKO F1 generation were generated by crossing with wild-type pigs, and their genotype was detected by T7ENI assay and sequencing. GHRKO F2 generation was obtained via self-cross of GHRKO F1 pigs. Their genotypes of GHRKO F2 generation was also detected by Sanger sequencing.ResultsIn total, 19 of 20 single-cell colonies exhibited biallelic modified GHR (95%), and the efficiency of DNA deletion mediated by dual-sgRNAs/Cas9 was as high as 90% in 40 GHR alleles of 20 single-cell colonies. Two types of GHR allelic single-cell colonies (GHR−47/−1, GHR−47/−46) were selected as donor cells for the generation of GHRKO pigs. The reconstructed embryos were transferred into 15 recipient gilts, resulting in 15 GHRKO newborn piglets and 2 fetuses. The GHRKO pigs exhibited slow growth rates and small body sizes. From birth to 13 months old, the average body weight of wild-type pigs varied from 0.6 to 89.5 kg, but that of GHRKO pigs varied from only 0.9 to 37.0 kg. Biochemically, the knockout pigs exhibited decreased serum levels of IGF-I and glucose. Furthermore, the GHRKO pigs had normal reproduction ability, as eighteen GHRKO F1 piglets were obtained via mating a GHRKO pig with wild-type pigs and five GHRKO F2 piglets were obtained by self-cross of F1 generation, indicating that modified GHR alleles can pass to the next generation via germline transmission.ConclusionThe dual-sgRNAs/Cas9 is a reliable system for DNA deletion and that GHRKO pigs conform to typical phenotypes of those observed in Laron patients, suggesting that these pigs could serve as an appropriate model for Laron syndrome.

Frequency of the exon 3-deleted/full-length growth hormone receptor polymorphism in Saudi Arabian population.

Objectives:To investigate the frequency of the growth hormone receptor (GHR)-d3 polymorphism in a random sample of Saudi Arabian population from Jazan province, and test the effects of the polymorphism on some anthropometric factors.Methods:This cross-sectional population-based study was conducted during the period from January to April 2017 at the College of Applied Medical Sciences, Jazan University, Southwestern Saudi Arabia. A total of 230 healthy adult male and female volunteers were randomly recruited. Genomic DNA was extracted from the whole blood, and the GHR exon 3 locus was genotyped using multiplex polymerase chain reaction.Results:The distributions of the GHR genotypes were as follows: fl/fl (39.1%), fl/d3 (44.8%), and d3/d3 (16.1%). No statistically significant differences were found between fl/fl, fl/d3, or d3/d3 GHR genotypes in terms of weight (p=0.90), height (p=0.12), or body mass index (BMI) (p=0.83) values.Conclusion:No correlations were found between the GHR-d3 polymorphism and weight, height, or BMI.

Genetic Polymorphisms as Predictive Markers of Response to Growth Hormone Therapy in Children with Growth Hormone Deficiency.

Objective Growth hormone (GH) deficiency (GHD) is commonly treated with recombinant human GH (rhGH). Individual response to rhGH therapy varies widely and there is evidence that variations in growth-related genes, e. g. the GH receptor (GHR) gene, may impact treatment response. We aimed to identify genetic polymorphisms which could serve as predictive markers of response to rhGH therapy. Methods We conducted a genetic analysis of single nucleotide polymorphisms (SNPs) and the GHR exon 3 deletion in 101 paediatric GHD patients receiving rhGH. Patients were analysed for 13 known SNPs in 11 genes of the GH axis (SOS1, IGFR1, GAB1, LHX4, IGFBP3, GRB10, GHRHR, GHSR), growth plate (VDR, ESR1) and cell cycle (CDK4). Individual index of responsiveness (IoR) values were compared by genotype. We also analysed the potential association between the IoR and the GHR exon 3 deletion. IoRs were analysed by genotype by one-way analysis of variance and unpaired t-test. Results Variations in two SNPs, rs2888586 (SOS1) and rs2069502 (CDK4), and the GHR exon 3 deletion were significantly associated with response to rhGH treatment. Conclusions Genetic variations are potentially suitable as predictive markers of rhGH treatment response in GHD. Genetic analysis provides a starting point for individualised treatment of GHD.

The GH receptor exon 3 deletion is a marker of male-specific exceptional longevity associated with increased GH sensitivity and taller stature.

Although both growth hormone (GH) and insulin-like growth factor 1 (IGF-1) signaling were shown to regulate life span in lower organisms, the role of GH signaling in human longevity remains unclear. Because a GH receptor exon 3 deletion (d3-GHR) appears to modulate GH sensitivity in humans, we hypothesized that this polymorphism could play a role in human longevity. We report a linear increased prevalence of d3-GHR homozygosity with age in four independent cohorts of long-lived individuals: 841 participants [567 of the Longevity Genes Project (LGP) (8% increase; P = 0.01), 152 of the Old Order Amish (16% increase; P = 0.02), 61 of the Cardiovascular Health Study (14.2% increase; P = 0.14), and 61 of the French Long-Lived Study (23.5% increase; P = 0.02)]. In addition, mega analysis of males in all cohorts resulted in a significant positive trend with age (26% increase; P = 0.007), suggesting sexual dimorphism for GH action in longevity. Further, on average, LGP d3/d3 homozygotes were 1 inch taller than the wild-type (WT) allele carriers (P = 0.05) and also showed lower serum IGF-1 levels (P = 0.003). Multivariate regression analysis indicated that the presence of d3/d3 genotype adds approximately 10 years to life span. The LGP d3/d3-GHR transformed lymphocytes exhibited superior growth and extracellular signal-regulated kinase activation, to GH treatment relative to WT GHR lymphocytes (P < 0.01), indicating a GH dose response. The d3-GHR variant is a common genetic polymorphism that modulates GH responsiveness throughout the life span and positively affects male longevity.

Growth hormone receptor exon 3 isoforms may have no importance in the clinical setting of multiethnic Brazilian acromegaly patients.

Acromegaly is associated with significant morbidity and increased mortality, but has a variable severity phenotype. The presence of the exon 3-deleted isoform of the growth hormone receptor (d3-GHR) may influence the disease phenotype and treatment outcomes, including the frequency of biochemical discordance after medical treatment. The objective of this study was to analyze the influence of the d3-GHR isoform on clinical and biochemical characteristics and in the treatment outcomes of Brazilian multiethnic acromegaly patients. We retrospectively analyzed our acromegaly outpatient clinic databank and collected demographic, clinical, biochemical and treatment outcome data from those patients who agreed to participate in the study. A blood sample was collected from all patients, the DNA was extracted and the GHR isoforms were evaluated by PCR, with the full length (fl)-GHR represented by a 935-bp fragment and the d3-GHR represented by a 532-bp fragment. A total of 121 patients were included. Fifty-six patients (46.3%) were full-length homozygous (fl/fl), 48 (39.7%) were heterozygous (fl/d3) and 17 (14.0%) were d3-GHR homozygous (d3/d3). There was no difference between patients homozygous for the fl isoform and those harboring at least one d3-GHR allele in the demographic, clinical and biochemical data or in the treatment outcomes, including somatostatin receptor ligands (SRL) monotherapy, combination therapy with SRL and cabergoline and pegvisomant treatment. There was also no difference between the groups for the frequency of GH and IGF-I discordance after medical treatment. GHR exon 3 genotyping appears to have no clinical significance, at least in Brazilian acromegaly patients.

Rapid method for Growth Hormone Receptor exon 3 delete (GHRd3) SNP genotyping from archival human placental samples

Analysis of archival samples from cohorts of pregnant women may be key to discovering prognosticators of stillbirth and pregnancy/perinatal complications. Growth hormone (GH) and its receptor (GHR) are pivotal in feto-placental development and pregnancy maintenance. We report a rapid, optimized method for genotyping the GHR full-length versus exon 3-deleted isoform (GHRd3). TaqMan single nucleotide polymorphism (SNP) genotyping proved superior to standard multiplex polymerase chain reaction (PCR) in allele detection and GHR genotyping from archived samples, including those with poor genomic deoxyribonucleic acid quality/quantity such as formalin fixed, paraffin embedded, blood, and serum. Furthermore, this assay is suitable for high through put 96 or 384-well plate quantitative PCR machines with automated genotype calling software. The TaqMan genotyping assay can increase the data obtained from precious archival human samples.

Rapid method for growth hormone receptor exon 3 delete (GHRd3) SNP genotyping from archival human placental samples.

Analysis of archival samples from cohorts of pregnant women may be key to discovering prognosticators of stillbirth and pregnancy/perinatal complications. Growth hormone (GH) and its receptor (GHR) are pivotal in feto-placental development and pregnancy maintenance. We report a rapid, optimized method for genotyping the GHR full-length versus exon 3-deleted isoform (GHRd3). TaqMan single nucleotide polymorphism (SNP)genotyping proved superior to standard multiplex polymerase chain reaction (PCR) in allele detection and GHR genotyping from archived samples, including those with poor genomic deoxyribonucleic acid quality/quantity such as formalin fixed, paraffin embedded, blood, and serum. Furthermore, this assay is suitable for high through put 96 or 384-well plate quantitative PCR machines with automated genotype calling software. The TaqMan genotyping assay can increase the data obtained from precious archival human samples.

Influence of growth hormone receptor exon 3 polymorphism on growth response in children with growth hormone deficiency

Results The distribution of GHR exon 3 isoforms in children with GHD demonstrated that the frequency of fl/fl (82.8%) is higher than that in most of European studies. There was no significant difference in baseline height SDS between 2 groups. Height velocity during the first year of growth hormone replacement therapy tended to be higher in subjects who have d3 allele (fl/d3 and d3/d3), but there was no statistical difference according to genotype.

Growth hormone responsiveness: why does it vary and can it be predicted?

Initial response to growth hormone (GH) varies considerably. In severe GH deficiency initial response varies across the group by almost 100%. In common non-GH deficient disorders such as idiopathic short stature (ISS) and children born small for gestational age (SGA) initial response varies by more than 100%. The explanation for the wide response to GH treatment can be clustered into three broad groups; (i) non-compliance with GH therapy, (ii) clinical characteristics associated with GH responsiveness and (iii) mutations and common gene variants in the GH-IGF-I axis. (i) Non-compliance with GH therapy: The commonest explanation for variable GH response is missed GH doses. In a national prospective study of GH compliance in New Zealand children; 34% of children missed more than one GH dose per week. Maori and Pacific children missed an additional GH dose each week than Caucasian children. Predictably, poor compliance (≥4 doses/week missed) was associated with a far poorer growth response than good compliance (height velocity SDS +0.4 vs +2.8). Even moderate compliance (2-3 doses/week missed) was associated with a poorer growth response (height velocity SDS +1.4 versus +2.8). Interestingly, paediatricians were unaware of GH non-compliance. GH response can only be maximised when more effective GH delivery devices are developed that record the date and time GH is administered to enable paediatricians to more effectively address compliance. (ii) Clinical characteristics associated with GH responsiveness: There is a differential response to GH therapy according to the underlying disorder. GH deficient children are more responsive than those with Turner Syndrome or idiopathic short stature who are in turn more responsive than SGA children (as shown by height velocity and serum IGF-I for a given GH dose). Furthermore, across the normal birth weight range we have recently shown that progressive reduction in birth weight SDS is associated with a progressively lower IGF-I response during IGF-I generation testing. Across growth disorders; more severe GH deficiency, taller parents, shorter stature, younger age at the start of treatment and heavier children are all parameters found to be associated with greater initial and sustained response to GH treatment. Michael Ranke has pioneered individualised GH dosing through GH prediction modelling across growth disorders. GH response can be predicted by inserting common clinical characteristics into a prediction equation that includes adjusting the dose. Prediction modelling is of greatest benefit to children with adverse clinical characteristics in whom greater initial GH doses will lead to greater growth response. (iii) Mutations and common gene variants in the GH-IGF-I axis: Downstream gene mutations in this axis (GH receptor, IGF-I and IGF-I receptor) are relatively rare causes of short stature, poor growth and GH response. Conversely common gene variants are being increasingly sought that influence stature, growth and GH responsiveness. Initial reports suggested a common GH receptor exon 3 deletion was associated with a better response to GH than the full length form in SGA and ISS children. Further studies have found little if any effect of the GH receptor deletion on initial or sustained growth response in SGA, Turner Syndrome or GH deficiency. Future studies are likely to focus on panels of common gene variants across the GH axis rather than examining individual genes to better characterise GH responsiveness.

The growth hormone receptor exon 3-deleted/full-length polymorphism and response to growth hormone therapy in prepubertal idiopathic short children

ObjectiveThe primary aim of the study was to evaluate d3-GHR as a possible cause of increased GH sensitivity in children with delayed infancy-childhood transition (DICT). The secondary aim was to investigate the impact of the GHR exon 3 deleted/full-length (d3/fl) polymorphism on GH treatment response in prepubertal children classified as having idiopathic short stature (ISS). DesignStudy subjects included 167 prepubescent longitudinally followed children classified as having ISS. Children were randomized to standard-dose GH treatment (33μgkg−1day−1), to double-dose treatment (67μgkg−1day−1), or to an untreated control group. Growth and metabolic outcome were evaluated at birth (n=166), after one year of treatment (n=59) and at adult height (n=145). Genotyping of the GHR d3/fl polymorphism was performed using TaqMan SNP genotyping of tagSNP rs6873545. ResultsBirth and early growth data did not reach the predetermined level of statistical significance for difference between genotypes. Growth and IGF-1 response after one year of GH treatment did not differ between genotypes. IGFBP-3SDS was higher in untreated d3-GHR carriers than in untreated fl/fl individuals, whereas there was insufficient evidence for higher IGFBP-3SDS in treated d3-GHR carriers. Genotype did not explain the growth response to treatment, and no differences in heightSDS, height gain, or difference in height to midparental heightSDS between genotype groups were found at adult height. ConclusionThe common GHR d3/fl polymorphism is probably not a cause of DICT in children with ISS, and our results do not suggest that the d3-GHR genotype is associated with increased sensitivity to GH in children with ISS.

Association between the Growth Hormone Receptor Exon 3 Polymorphism and Metabolic Factors in Korean Patients with Acromegaly

BackgroundThis study investigated the association between the frequency of growth hormone receptor (GHR) exon 3 polymorphism (exon 3 deletion; d3-GHR) and metabolic factors in patients with acromegaly in Korea.MethodsDNA was extracted from the peripheral blood of 30 unrelated patients with acromegaly. GHR genotypes were evaluated by polymerase chain reaction and correlated with demographic data and laboratory parameters.ResultsNo patient had the d3/d3 genotype, while four (13.3%) had the d3/fl genotype, and 26 (86.7%) had the fl/fl genotype. Body mass index (BMI) in patients with the d3/fl genotype was significantly higher than in those with the fl/fl genotype (P=0.001). Age, gender, blood pressure, insulin-like growth factor-1, growth hormone, fasting plasma glucose, triglycerides, high density lipoprotein cholesterol, and low density lipoprotein cholesterol levels showed no significant differences between the two genotypes.ConclusionThe d3-GHR polymorphism may be associated with high BMI but not with other demographic characteristics or laboratory parameters.

The GH receptor exon 3 deleted/full-length polymorphism is associated with central adiposity in the general population.

To test the hypothesis that the GH receptor (GHR) exon 3 deleted (d3)/full-length (fl) polymorphism influences anthropometry and body composition in the general population. The Swedish Obese Subjects (SOS) reference study is a cross-sectional population-based study, randomly selected from a population registry. A subgroup of the population-based Malmö Diet and Cancer study (MDC-CC) was used as a replication cohort. The SOS reference study comprises 1135 subjects (46.2% men), with an average age of 49.5 years. The MDC-CC includes 5451 successfully genotyped subjects (41.5% men), with an average age of 57.5 years. GHR d3/fl genotypes were determined using TagSNP rs6873545. Linear regression analyses were used to test for genotype-phenotype associations. In the SOS reference study, subjects homozygous for the d3-GHR weighed ∼4 kg more (P=0.011), and had larger waist-to-hip ratio (WHR, P=0.036), larger waist circumference (P=0.016), and more fat-free mass estimated from total body potassium (P=0.026) than grouped fl/d3 and fl/fl subjects (d3-recessive genetic model). The association with WHR was replicated in the MDC-CC (P=0.002), but not those with other anthropometric traits. In this population-based study, the GHR d3/fl polymorphism was found to be of functional relevance and associated with central adiposity, such that subjects homozygous for the d3-GHR showed an increased abdominal obesity.

Genetic predictors of long-term response to growth hormone (GH) therapy in children with GH deficiency and Turner syndrome: the influence of a SOCS2 polymorphism.

There is great interindividual variability in the response to GH therapy. Ascertaining genetic factors can improve the accuracy of growth response predictions. Suppressor of cytokine signaling (SOCS)-2 is an intracellular negative regulator of GH receptor (GHR) signaling. The objective of the study was to assess the influence of a SOCS2 polymorphism (rs3782415) and its interactive effect with GHR exon 3 and -202 A/C IGFBP3 (rs2854744) polymorphisms on adult height of patients treated with recombinant human GH (rhGH). Genotypes were correlated with adult height data of 65 Turner syndrome (TS) and 47 GH deficiency (GHD) patients treated with rhGH, by multiple linear regressions. Generalized multifactor dimensionality reduction was used to evaluate gene-gene interactions. Baseline clinical data were indistinguishable among patients with different genotypes. Adult height SD scores of patients with at least one SOCS2 single-nucleotide polymorphism rs3782415-C were 0.7 higher than those homozygous for the T allele (P < .001). SOCS2 (P = .003), GHR-exon 3 (P= .016) and -202 A/C IGFBP3 (P = .013) polymorphisms, together with clinical factors accounted for 58% of the variability in adult height and 82% of the total height SD score gain. Patients harboring any two negative genotypes in these three different loci (homozygosity for SOCS2 T allele; the GHR exon 3 full-length allele and/or the -202C-IGFBP3 allele) were more likely to achieve an adult height at the lower quartile (odds ratio of 13.3; 95% confidence interval of 3.2-54.2, P = .0001). The SOCS2 polymorphism (rs3782415) has an influence on the adult height of children with TS and GHD after long-term rhGH therapy. Polymorphisms located in GHR, IGFBP3, and SOCS2 loci have an influence on the growth outcomes of TS and GHD patients treated with rhGH. The use of these genetic markers could identify among rhGH-treated patients those who are genetically predisposed to have less favorable outcomes.

The growth hormone receptor exon 3 polymorphism is not associated with height or metabolic traits in healthy young adults

ContextThe GHR polymorphisms contribution to the interindividual variability in prenatal and postnatal growth as well as to metabolic traits is controversial. ObjectiveThe aim of this study is to analyze the association of the GHRfl/d3 polymorphism with prenatal and postnatal growth and metabolic outcomes in adult life and to compare the genotype distribution in different populations. Design385 community healthy subjects followed from birth to adult life (23–25years old) were grouped according to birth size: small—SGA (n=130, 62 males), appropriate—AGA (n=162, 75 males) and large for gestational age—LGA (n=93, 48 males). GHRfl/d3 genotype distribution and its potential association with anthropometric (at birth, childhood and adult life) and metabolic features (in adult life) were analyzed and compared with data obtained from a systematic review of GHRfl/d3 association studies (31 articles). ResultsThe frequency of the GHR d3/d3 genotype was lower in the LGA (χ2 p=0.01); SGA and AGA subjects exhibited an increased chance of the d3/d3 genotype (OR=3.58; 95%CI: 1.55; 8.24) and (OR=2.39; 95%CI: 1.02; 5.62), respectively. Despite the different prevalence among different birth size groups, in adults, GHRfl/d3 genotype was not associated with height, plasma IGF1 levels or metabolic phenotype and cardiovascular risk. GHRfl/d3 genotype distributions in AGA, SGA and LGA groups were comparable with those found in subjects of European origin but not with those of Asian ancestry. ConclusionsThe GHRd3 genotype was negatively associated with birth size but it was not associated with adult height or weight, plasma IGF1, metabolic phenotype or any marker of increased cardiovascular risk in young adults.

SNPs within the GH-signaling pathway are associated with the early IGF1 response to GH replacement therapy in GHD adults

GH-deficient (GHD) adults have reduced serum concentrations of IGF1. GH replacement therapy increases serum IGF1 concentrations, but the interindividual variation in treatment response is large and likely influenced by genetic factors. This study was designed to test the hypothesis that single-nucleotide polymorphisms (SNPs) in genes within the GH signaling pathway influence the serum IGF1 response to GH replacement. A total of 313 consecutive GHD adults (58.1% men; mean age 49.7 years) were studied before and after 1 week, 6 months, and 1 year of GH treatment. GH dose was individually titrated to normalize serum IGF1 levels. Six SNPs in the GH receptor (GHR) and the GH signaling pathway (JAK2, STAT5B, SOCS2, and PIK3CB) genes were selected for genotyping. The GHR exon 3-deleted/full-length (d3/fl) polymorphism was analyzed using tagSNP rs6873545. After 1 week of GH replacement, homozygotes of the fl-GHR showed a better IGF1 response to GH than carriers of the d3-GHR (P=0.016). Conversely, homozygotes of the minor allele of PIK3CB SNP rs361072 responded better than carriers of the major allele (P=0.025). Compared with baseline, both SNPs were associated with the IGF1 response at 6 months (P=0.041 and P=0.047 respectively), and SNP rs6873545 was further associated with the IGF1 response at 1 year (P=0.041). Our results indicate that common genetic variants in the GH signaling pathway may be of functional relevance to the response to GH replacement in GHD adults.