The -202 A allele of insulin-like growth factor binding protein-3 (IGFBP3) promoter polymorphism is associated with higher IGFBP-3 serum levels and better growth response to growth hormone treatment in patients with severe growth hormone deficiency

The Year in Growth and Short Stature

The papers and communications selected here, published in 2020-2021, report major advances in pathophysiology, diagnostics, treatment and patient care in the fields of growth hormones and disorders. © 2022 French Society of Pediatrics. Published by Elsevier Masson SAS. All rights reserved.

Molecular diagnosis for growth hormone deficiency in Chinese children and adolescents and evaluation of impact of rare genetic variants on treatment efficacy of growth hormone

BACKGROUND

Growth hormone is an effective therapy for growth hormone deficiency (GHD) but with a rather variable individual sensitivity. It is unclear whether rare genetic variants may contribute to the differential GH responsiveness.

METHODS

The present study aims to investigate the molecular etiology of GHD in Chinese children and adolescents and evaluate the impact of rare variants on therapeutic efficacies of GH.

RESULTS

Twenty-one rare heterozygous variant were classified as promising uncertain significance (n = 14), pathogenic (n = 5) or likely pathogenic (n = 2) for 21 of the 93 GHD patients. After GHD patients harboring these rare variants were excluded, inter-individual variability in the response to GH therapy obviously reduced and the negative correlation between initiation age of treatment and height SDS change became stronger in the group without rare variants. Among rare variants, 7 (likely) pathogenic variants (7.5%, 7/93) involved a total of 6 genes not only associated with GH secretion (PROKR2, LZTR1), but also growth plate chondrocyte signaling (ACAN, FBN1, COL9A1) or genetic syndromes (PTPN11).

CONCLUSIONS

Rare genetic variants are an important factor contributing to differential GH responsiveness and genetic testing should be factored into accurate diagnosis and treatment decision making in the future.

CLINICAL TRIAL REGISTRATION NUMBER

ChiCTR1900026510.

Investigating whether serum IGF-1 and IGFBP-3 levels reflect the height outcome in prepubertal children upon rhGH therapy: LG growth study database

Serum insulin-like growth factor-1 (IGF-I) and IGF binding protein-3 (IGFBP-3) levels can be used to monitor the safety of recombinant human growth hormone (rhGH) therapy. In this study, we evaluated the changes in serum IGF-I and IGFBP-3 levels during rhGH therapy as a marker of height outcome in prepubertal children. Totally, 705 prepubertal children with short stature were enrolled from the LG Growth Study Database. Data for three groups of subjects were obtained as follows: Idiopathic GH deficiency (IGHD; n = 486); idiopathic short stature (n = 66); small for gestational age (n = 153). Serum IGF-I and IGFBP-3 levels at the baseline and after the 1st and 2nd year of rhGH therapy, as well as the Δheight standard deviation score (SDS), were obtained. Δheight SDS after the 1st and 2nd year of rhGH therapy had notably increased compared to that at the baseline for all three groups. IGF-I and IGFBP-3 levels in all three groups were significantly increased compared to those at the baseline (p <0.001). Δheight SDS was positively correlated with ΔIGF-1 SDS after the 1st year of therapy, ΔIGFBP-3 SDS after the 2nd year of therapy in the IGHD group, and ΔIGF-I SDS and ΔIGFBP-3 SDS after the 2nd year of therapy (p < 0.05), regardless of whether the height at the baseline was a covariate. The increase in IGF-I and IGFBP-3 levels during rhGH therapy was related to the growth response in children with IGHD. Therefore, it may be valuable to measure the change in serum IGF-I and IGFBP-3 levels, especially the latter, during rhGH treatment to predict the growth response upon long-term treatment.

Evaluation of Growth Hormone Results in Different Diagnosis and Trend Over 10 Year of Follow-up: A Single Center Experience

OBJECTIVE

The aim was to evaluate the results of diagnosis, follow-up and treatment of the patients who recieved growth hormone (GH) treatment for the last 10 years and to determine the differences in the process and results over the years.

METHODS

Anthropometric, clinical, laboratory data, treatment adherence and side effects were evaluated retrospectively in 767 patients who recieved GH treatment between 2009-2018. Patients were grouped as isolated GH deficiency (IGHD), multiple pituitary hormone deficiency (MPHD), small for gestational age (SGA), and Turner syndrome (TS) depending on diagnosis.

RESULTS

GH treatment was started in 689 cases (89.8%) with IGHD, 24 (3.1%) with MPHD, 26 (3.4%) with SGA and 28 (3.7%) with TS. Median age of GH treatment onset was the earliest in SGA (8.4 years) and the latest in the IGHD group (12.0 years). At the time of treatment cessation, height standard deviation score (SDS) in IGHD and MPHD was significantly higher than treatment initiation time, whereas there was no significant difference in TS and SGA. One hundred eighty-nine cases reached the final height. Final heights for girls/boys were: IGHD 154/164.9 cm; MPHD 156.2/163.5 cm; TS 146.7 cm; and SGA 145.7/-cm, respectively. Target height SDS-final height SDS median values were IGHD: 0.1, MPHD: 0.6, SGA: 0.5, TS: 2.4 respectively. The patients’ treatment compliance was high (92%) and the incidence of side effects was low (2.7%).

CONCLUSION

In our cohort, GH treatment start age was late and no difference in this was observed in the last 10 years. The improvement in the height SDS was most marked in the IGHD and MPHD groups, the least in the TS and SGA groups.

Pharmacogenomics applied to recombinant human growth hormone responses in children with short stature

We present current knowledge concerning the pharmacogenomics of growth hormone therapy in children with short stature. We consider the evidence now emerging for the polygenic nature of response to recombinant human growth hormone (r-hGH). These data are related predominantly to the use of transcriptomic data for prediction. The impact of the complex interactions of developmental phenotype over childhood on response to r-hGH are discussed. Finally, the issues that need to be addressed in order to develop a clinical test are described.

Relationship between growth velocity and change of levels of insulin-like growth factor-1, insulin-like growth factor binding protein-3 and, IGFBP-3 promoter polymorphism during GnRH agonist treatment

PURPOSE

This study aims to investigate the effect of gonadotropin-releasing hormone agonist (GnRHa) on the growth hormone (GH)-insulin-like growth factor-1 (IGF-1) axis and to evaluate whether -202 A/C IGF binding protein-3 (IGFBP-3) promoter polymorphism affects growth velocity in females with central precocious puberty (CPP) during treatment.

METHODS

Data was collected from 97 females younger than 9 years, diagnosed with precocious puberty and treated with GnRHa for at least 1 year at Kangdong Sacred Heart Hospital from 2014 to 2015. Their body height, weight, change in height standard deviation score (∆SDS), serum IGF-1, serum IGFBP-3, bone age, and -202 A/C IGFBP-3 promoter polymorphism were measured before and after GnRHa treatment. The interrelationships between the variables were calculated.

RESULTS

During treatment, height SDS, IGF-1 SDS, IGFBP-3 SDS, and IGF-1/IGFBP-3 ratio significantly decreased. A significant correlation was observed between ∆IGF-1 SDS and ∆height SDS (r=0.405, P<0.001). The presence of the C allele was significantly correlated with IGF-1 SDS after treatment (P=0.049) and with IGFBP-3 SDS before and after treatment (P=0.012 and P=0.001), but not with ∆IGF-1 SDS, ∆IGFBP-3 SDS, ∆IGF-1/IGFBP-3 ratio, or ∆height SDS.

CONCLUSION

Growth velocity during GnRHa treatment is related to ∆IGF-1 SDS, indicating the apparent impact of GnRHa on the GH-IGF-1 axis. The -202 A/C IGFBP-3 promoter polymorphism does not affect the growth velocity of GnRHa in CPP girls.

A Genome-Wide Pharmacogenetic Study of Growth Hormone Responsiveness

CONTEXT

Individual patients vary in their response to growth hormone (GH). No large-scale genome-wide studies have looked for genetic predictors of GH responsiveness.

OBJECTIVE

To identify genetic variants associated with GH responsiveness.

DESIGN

Genome-wide association study (GWAS).

SETTING

Cohorts from multiple academic centers and a clinical trial.

PATIENTS

A total of 614 individuals from 5 short stature cohorts receiving GH: 297 with idiopathic short stature, 276 with isolated GH deficiency, and 65 born small for gestational age.

INTERVENTION

Association of more than 2 million variants was tested.

MAIN OUTCOME MEASURES

Primary analysis: individual single nucleotide polymorphism (SNP) association with first-year change in height standard deviation scores. Secondary analyses: SNP associations in clinical subgroups adjusted for clinical variables; association of polygenic score calculated from 697 genome-wide significant height SNPs with GH responsiveness.

RESULTS

No common variant associations reached genome-wide significance in the primary analysis. The strongest suggestive signals were found near the B4GALT4 and TBCE genes. After meta-analysis including replication data, signals at several loci reached or retained genome-wide significance in secondary analyses, including variants near ST3GAL6. There was no significant association with variants previously reported to be associated with GH response nor with a polygenic predicted height score.

CONCLUSIONS

We performed the largest GWAS of GH responsiveness to date. We identified 2 loci with a suggestive effect on GH responsiveness in our primary analysis and several genome-wide significant associations in secondary analyses that require further replication. Our results are consistent with a polygenic component to GH responsiveness, likely distinct from the genetic regulators of adult height.

Effect of -202 A/C IGFBP-3 polymorphisms on growth responses in children with idiopathic short stature

PURPOSE

This study evaluated the -202 A/C insulin-like growth factor binding protein 3 (IGFBP-3) promoter polymorphism as a predictor of serum IGFBP-3 concentration and growth velocity after recombinant growth hormone (rhGH) therapy in patients with idiopathic short stature (ISS).

METHODS

Genotyping and serial measurement of clinical parameters were performed in 69 children with a confirmed diagnosis of ISS. Restriction fragment length polymorphism analysis was performed to determine the genotype at the -202 IGFBP-3 locus. Serum insulin-like growth factor 1 (IGF-1) and IGFBP-3 levels were measured at baseline and after 1 year of rhGH treatment, as were height standard deviation score and growth velocity.

RESULTS

The -202 A/C IGFBP-3 genotype comprised 69.6% AA, 24.6% AC, and 5.8% CC. One year of treatment did not produce a meaningful difference in IGF-1 or IGFBP-3 levels between children in the AA group and those with at least one copy of the C allele (AC/CC group). Comparing the 2 groups after one year also revealed no significant difference in growth velocity (ΔHeight: 9.061±1.612 cm/yr in the AA group, 9.421±1.864 in the AC/CC group, P=0.419).

CONCLUSION

rhGH treatment was effective and there were no significant differences in IGF-1, IGFBP-3, or growth velocity according to genotype. Thus, -202 IGFBP-3 genotype may not be a major factor affecting individual growth responses in Korean children with ISS.

Effects of Eleutherococcus Extract Mixture on Endochondral Bone Formation in Rats

Eleutherococcus extract mixture (EEM) is an herbal mixture of dried stem of Eleutherococcus sessiliflorus and germinated barley, which has been highly effective, in previous screening and among the traditional medicines to tonify innate qi and acquired qi, respectively. In this study, we investigate the effects of EEM on endochondral bone formation. Female adolescent rats were given EEM, growth hormone or vehicle for 10 days. Tetracycline was intraperitoneally injected to light the fluorescent band 72 h before sacrifice to determine endochondral bone formation. In order to evaluate endocrine or paracrine/autocrine mechanisms, expressions of insulin-like growth factor 1 (IGF1), insulin-like growth factor binding protein 3 (IGFBP3), or bone morphogenetic protein 2 (BMP2) were evaluated after EEM administration in liver or growth plate (GP). EEM oral administration significantly increased endochondral bone formation and proliferative and hypertrophic zonal heights of tibial GP. EEM also upregulated hepatic IGF1 and IGFBP3 mRNA expressions, and IGF1 and BMP2 expressions in GP. Taken together, EEM increases endochondral bone formation through stimulating proliferation and hypertrophy with upregulation of hepatic IGF1 and IGFBP3 expressions. Considering immunohistochemical studies, the effect of EEM may be due to increased local IGF1 and BMP2 expression in GP, which may be considered growth hormone (GH)-dependent endocrine and autocrine/paracrine pathways.

Lack of association between genetic polymorphisms in IGF1 and IGFBP3 with twin births in a Brazilian population (Cândido Godói, Rio Grande do Sul)

Insulin-like growth factor (IGF-1) is an important peptide hormone involved in the reproduction and fetal development of mammals, and it is suggested that it may influence the human twinning rate. This study aimed to test such possible association, investigating the genetic polymorphisms IGF1 (CA)n and IGFBP3 rs2854744 in the population from Candido Godoi (CG), a small city located in the South of Brazil that has a high prevalence of twin births. A case-control study was performed comprising a total of 39 cases (representing about 40% of the mothers of twins who were born in CG after 1995) and 214 controls (mothers of non-twin children), 97 of whom were living in CG while 117 were living in Porto Alegre. DNA was extracted from blood leucocytes and genotyping was performed. According to the statistical analyses, there was no significant difference in the frequencies of both studied genetic polymorphisms when comparing case group with control group. Thus, our results pointed to a lack of association between IGF1 (CA)n and IGFBP3 rs2854744 polymorphisms and twin births in CG, but further investigations in other populations with different characteristics must be performed to confirm the role of IGF-I in human twinning.

The in vitro functional analysis of single-nucleotide polymorphisms associated with growth hormone (GH) response in children with GH deficiency

Response to recombinant human growth hormone (r-hGH) in the first year of therapy has been associated with single-nucleotide polymorphisms (SNPs) in children with GH deficiency (GHD). Associated SNPs were screened for regulatory function using a combination of in silico techniques. Four SNPs in regulatory sequences were selected for the analysis of in vitro transcriptional activity (TA). There was an additive effect of the alleles in the four genes associated with good growth response. For rs3110697 within IGFBP3, rs1045992 in CYP19A1 and rs2888586 in SOS1, the variant associated with better growth response showed higher TA with r-hGH treatment. For rs1024531 in GRB10, a negative regulator of IGF-I signalling and growth, the variant associated with better growth response had a significantly lower TA on r-hGH stimulation. These results indicate that specific SNP variants have effects on TA that provide a rationale for their clinical impact on growth response to r-hGH therapy.

Effects of Astragalus Extract Mixture HT042 on Height Growth in Children with Mild Short Stature: A Multicenter Randomized Controlled Trial

HT042 is a standardized functional food ingredient approved by Korean Food and Drug Administration with a claim 'HT042 can help height growth of children'. We aimed to evaluate the safety and efficacy of HT042 on height growth in children with mild short stature. A multicenter, randomized, double-blind, placebo-controlled parallel study was performed on children aged 6-8 years with height ranked below the 25th percentile. In 129 children, height gain was significantly higher in HT042 group than placebo group after 24 weeks (mean difference, 0.29 cm; 95% CI, 0.01 to 0.57 cm; p = 0.027). The difference was elevated when the efficacy analysis was restricted to children below the 10th percentile (mean difference, 0.45 cm; 95% CI, 0.04 to 0.87 cm; p = 0.031). Because bone age advancement was lower in HT042 group, height standard deviation score gain for bone age was higher in HT042 group and the difference was significant in children below the 10th percentile (mean difference, 0.20 score; 95% CI, 0.00 to 0.39 points; p = 0.045). Serum IGF-1 and IGFBP-3 levels were significantly increased compared with baseline within HT042 group, but group difference was not significant. HT042 supplementation helped to increase height growth in children without skeletal maturation and was more effective in much shorter children. The effects might be mediated by increases in serum IGF-1 and IGFBP-3 levels. Copyright © 2017 John Wiley & Sons, Ltd.

Astragalus Extract Mixture HT042 Increases Longitudinal Bone Growth Rate by Upregulating Circulatory IGF-1 in Rats

Astragalus extract mixture HT042 is a standardized ingredient of health functional food approved by Korean FDA with a claim of “height growth of children.” HT042 stimulates bone growth rate and increases local IGF-1 expression in growth plate of rats which can be considered as direct stimulation of GH and its paracrine/autocrine actions. However, it remains unclear whether HT042 stimulates circulatory IGF-1 which also plays a major role to stimulate bone growth. To determine the effects on circulatory IGF-1, IGF-1 and IGFBP-3 expressions and phosphorylation of JAK2/STAT5 were evaluated in the liver after 10 days of HT042 administration. HT042 upregulated liver IGF-1 and IGFBP-3 mRNA expression, IGF-1 protein expression, and phosphorylation of JAK2/STAT5. HT042 also increased bone growth rate and proliferative zonal height in growth plate. In conclusion, HT042 stimulates bone growth rate via increment of proliferative rate by upregulation of liver IGF-1 and IGFBP-3 mRNA followed by IGF-1 protein expression through phosphorylation of JAK2/STAT5, which can be regarded as normal functioning of GH-dependent endocrine pathway.

Treatment of growth hormone deficiency in children, adolescents and at the transitional age

Recombinant human growth hormone (rhGH) has been available since 1985. Before 1985 growth hormone (GH) was extracted from cadaveric pituitary glands, but this was stopped in most countries that year, following the recognition that it could transmit Creutzfeldt-Jacob disease. The primary goal of rhGH treatment in GHD patients is to normalize height during childhood and adolescence and attain an adult height within the normal range and within the target height range (genetic potential). Genome-wide association studies have been used increasingly to study the genetic influence on height. There is a wide response to rhGH therapy, likely due to compliance issues, severity of GH deficiency and patient's sensitivity to rhGH. While some pediatric endocrinologists will use a fixed dose of rhGH, most will use an auxology-based dosing approach. This will involve starting at the lower end of the dose range and then titrating upwards based on the patient's response to therapy with measurement of IGF-1 concentrations to ensure that the patient is not over treated or undertreated. Although treatment of children with GHD with rhGH has generally been safe, careful follow-up by a pediatric endocrinologist in partnership with the pediatrician or primary care physician is recommended. The aim of this paper is to review the strategies and recommendations for treatment of GHD in children and patients in the transition to adult care.

EVALUATION OF FIRST YEAR RESPONSE TO TREATMENT IN CASES WITH GROWTH HORMONE DEFICIENCY

Background/Aims

Growth hormone (GH) treatment has severe cost burden on patients, their families, and healthcare systems. Therefore, accuracy of diagnosis should be confirmed; factors affecting the response to treatment should be defined. The present study is performed to evaluate auxiliary diagnostic parameters and factors affecting treatment in growth hormone deficiency (GHD).

Methods

In this study, 142 patients under the age of 16, with at least one year of treatment, were included. Treatment dose of somatropin was 0.2 mg/kg/week in all cases. Response to treatment was evaluated by measuring annual height and height standard deviation score (SDS) gains every 3 months.

Results

Male to female ratio was 79 to 63, and follow-up duration before the treatment was 0.89±0.38 years. Annual growth rate before the treatment was 2.92±1.02 cm, and age at the treatment initiation was 9.97±3.22 years. Height gain SDS at the end of the first year was significantly higher in cases which were at the prepuberty, had severe short stature, low height SDS-mid parental height SDS (HSDS-MPHSDS), and initiated treatment at earlier ages. Correlations in height gain and height SDS gain at the end of the first year were significant between bone age at treatment baseline, delta SDS factors, L-dopa and clonidine stimulation results (both are p<0.01).

Conclusion

Height gain was positively related to body mass index, whereas negatively to bone age at treatment baseline, responses obtained from stimulation tests, and delta SDS values. In the treatment evaluation, the parameters which can affect according to model chosen by the investigator, may differ.

Polymorphism in IGFBP3 gene is associated with prostate cancer risk: an updated meta-analysis

OBJECTIVE

Insulin-like growth factor-binding protein-3 (IGFBP3) is the major protein that binds with insulin-like growth factor-1 (IGF-1) and is considered to be involved in the development and progression of various cancers. We aimed to examine the association between prostate cancer (PCa) and the IGFBP3 gene-202A/C polymorphism.

METHODS

A comprehensive search within PubMed, EMBASE, and Cochrane Library was conducted to identify all case-control studies up to October 30, 2015, for a meta-analysis. Pooled odds ratios (ORs) and the 95% confidence intervals (CIs) were calculated using the fixed or random effects model.

RESULTS

Eighteen studies including 10,538 cases and 10,078 controls were identified. Overall, the CC genotype of IGFBP3-202A/C polymorphism was associated with increased risk of PCa in homozygote comparison (CC vs AA - OR =1.16, 95% CI: 1.08-1.25) and in recessive model (CC vs AA+AC - OR =1.11, 95% CI: 1.04-1.17). In dominant model, the CC/AC genotypes also implicated an increased risk of PCa (CC+AC vs AA - OR =1.11, 95% CI: 1.05-1.19). The C allele of IGFBP3-202A/C polymorphism was the risk allele for PCa relative to the A allele (OR =1.09, 95% CI: 1.05-1.14). Further stratification analysis revealed that the association between -202A/C polymorphism and PCa risk among Caucasians, but not in other ethnicities, was statistically significant (recessive model, OR =1.10, 95% CI: 1.02-1.19). In addition, the IGFBP3-202A/C polymorphism was associated with PCa risk in both population-based and hospital-based studies in homozygote comparison, recessive model, and allele model.

CONCLUSION

Our meta-analysis indicates that the IGFBP3-202A/C polymorphism is associated with the risk of PCa, particularly in Caucasians, with the C allele being the risk allele for PCa.

Effects of Phlomis umbrosa Root on Longitudinal Bone Growth Rate in Adolescent Female Rats

This study aimed to investigate the effects of Phlomis umbrosa root on bone growth and growth mediators in rats. Female adolescent rats were administered P. umbrosa extract, recombinant human growth hormone or vehicle for 10 days. Tetracycline was injected intraperitoneally to produce a glowing fluorescence band on the newly formed bone on day 8, and 5-bromo-2'-deoxyuridine was injected to label proliferating chondrocytes on days 8-10. To assess possible endocrine or autocrine/paracrine mechanisms, we evaluated insulin-like growth factor-1 (IGF-1), insulin-like growth factor binding protein-3 (IGFBP-3) or bone morphogenetic protein-2 (BMP-2) in response to P. umbrosa administration in either growth plate or serum. Oral administration of P. umbrosa significantly increased longitudinal bone growth rate, height of hypertrophic zone and chondrocyte proliferation of the proximal tibial growth plate. P. umbrosa also increased serum IGFBP-3 levels and upregulated the expressions of IGF-1 and BMP-2 in growth plate. In conclusion, P. umbrosa increases longitudinal bone growth rate by stimulating proliferation and hypertrophy of chondrocyte with the increment of circulating IGFBP-3. Regarding the immunohistochemical study, the effect of P. umbrosa may also be attributable to upregulation of local IGF-1 and BMP-2 expressions in the growth plate, which can be considered as a GH dependent autocrine/paracrine pathway.

Genetic Predictors of Response to Different Medical Therapies in Acromegaly

In the era of predictive medicine, management of diseases is evolving into a more personal and individualized approach, as more data are available regarding clinical, biochemical, radiological, molecular, histopathological, and genetic aspects. In the particular setting of acromegaly, which is a rare, chronic, debilitating, and disfiguring disease, an optimized approach deems even more necessary, especially because of an associated increased morbidity and mortality, the impact on patients' quality of life, and the increased cost of frequently necessary life-long treatments. In this paper, we review the available studies that address potential genetic influences on acromegaly, their role in the outcome, and response to treatments, as well as their contribution to the risk of developing side effects. We focus mainly on pharmacogenetic factors involved during treatment with dopamine agonists, somatostatin analogs, and pegvisomant. Specifically, mutations in dopamine receptors, somatostatin receptors, growth hormone receptors, and metabolic pathways involved in growth hormone action; polymorphisms in the insulin-like growth factor and the insulin-like growth factor binding proteins; and polymorphisms in other genes that may determine differences in the frequency of developing adverse events.

Influence of growth hormone receptor (GHR) exon 3 and -202A/C IGFBP-3 genetic polymorphisms on clinical and biochemical features and therapeutic outcome of patients with acromegaly

BACKGROUND

The association of GHR-exon 3 and -202 A/C IGFBP3 polymorphisms with clinical presentation, biochemical measurements and response to therapies in acromegaly have been suggested.

OBJECTIVE

To evaluate the presence of these polymorphisms in acromegaly and their influence on clinical and laboratorial characteristics of patients at diagnosis and after treatment in a large cohort of acromegalic patients.

PATIENTS AND METHODS

This is a cross-sectional study developed in a single tertiary reference center. Clinical data were obtained from the medical records of 186 acromegalic patients (116 women, age range 21-88 years). GH and IGF1 levels and GHR-exon 3 and -202 A/C IGFBP3 polymorphisms were evaluated in the same hospital.

RESULTS

At diagnosis, serum GH concentrations were lower in patients with GHR-d3 genotype than those with GHR-fl, whereas an association of lower IGFBP3 levels with d3 allele was observed only after neurosurgical or medical treatments. However, these associations were not confirmed in posterior statistical analysis.

CONCLUSION

Our results suggest that GHR-exon 3 and -202 A/C IGFBP3 polymorphisms did not show any consistent association on clinical and laboratorial features of acromegalic patients even after treatment.

Analysis of IGF(CA)19 and IGFBP3-202A/C gene polymorphisms in patients with acromegaly: association with clinical presentation and response to treatments

OBJECTIVE

IGF1 and IGFBP3 gene polymorphisms have been recently described. However, their potential role in the setting of acromegaly and its outcome is unknown. In this study, we analyze these polymorphisms in patients with acromegaly and investigate their association with clinical presentation and response to treatments.

DESIGN

A retrospective observational study was conducted in patients with acromegaly to analyze IGF1 and IGFBP3 gene polymorphisms.

METHODS

A total of 124 patients with acromegaly (57.3% women, mean age 44.9±13.1 years old) were followed up for a period of 11.4±8.0 years in eight tertiary referral hospitals in Spain. Clinical and analytical data were evaluated at baseline and after treatment. IGF1 and IGFBP3 gene polymorphisms were analyzed using PCR and specific primers.

RESULTS

Baseline laboratory test results were GH 19.3 (8.0-39.6) ng/ml, nadir GH 11.8 (4.1-21.5) ng/ml, and index IGF1 2.65±1.25 upper limit of normal. Regarding the IGF1 gene polymorphism, we did not find any association between the number of cyto-adenosine (CA) repeats and patients' baseline characteristics. Nevertheless, a trend for higher nadir GH values was observed in patients with <19 CA repeats. Regarding the IGFBP3 polymorphism, the absence of an A allele at the -202 position was associated with a higher baseline IGF1 and a higher prevalence of cancer and polyps. There were no differences in response to therapies according to the specific genotypes.

CONCLUSIONS

Polymorphisms in the IGF1 and IGFBP3 genes may not be invariably determinant of treatment outcome in acromegalic patients, but they may be associated with higher nadir GH levels or baseline IGF1, and determine a higher rate of colorectal polyps and cancer.

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

BACKGROUND

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.

OBJECTIVE

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).

DESIGN AND PATIENTS

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.

RESULTS

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).

CONCLUSION

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.

Genome-wide association and functional studies identify a role for IGFBP3 in hip osteoarthritis

OBJECTIVES

To identify genetic associations with hip osteoarthritis (HOA), we performed a meta-analysis of genome-wide association studies (GWAS) of HOA.

METHODS

The GWAS meta-analysis included approximately 2.5 million imputed HapMap single nucleotide polymorphisms (SNPs). HOA cases and controls defined radiographically and by total hip replacement were selected from the Osteoporotic Fractures in Men (MrOS) Study and the Study of Osteoporotic Fractures (SOF) (654 cases and 4697 controls, combined). Replication of genome-wide significant SNP associations (p ≤5×10(-8)) was examined in five studies (3243 cases and 6891 controls, combined). Functional studies were performed using in vitro models of chondrogenesis and osteogenesis.

RESULTS

The A allele of rs788748, located 65 kb upstream of the IGFBP3 gene, was associated with lower HOA odds at the genome-wide significance level in the discovery stage (OR 0.71, p=2×10(-8)). The association replicated in five studies (OR 0.92, p=0.020), but the joint analysis of discovery and replication results was not genome-wide significant (p=1×10(-6)). In separate study populations, the rs788748 A allele was also associated with lower circulating IGFBP3 protein levels (p=4×10(-13)), suggesting that this SNP or a variant in linkage disequilibrium could be an IGFBP3 regulatory variant. Results from functional studies were consistent with association results. Chondrocyte hypertrophy, a deleterious event in OA pathogenesis, was largely prevented upon IGFBP3 knockdown in chondrocytes. Furthermore, IGFBP3 overexpression induced cartilage catabolism and osteogenic differentiation.

CONCLUSIONS

Results from GWAS and functional studies provided suggestive links between IGFBP3 and HOA.

Isolated growth hormone deficiency (GHD) in childhood and adolescence: recent advances

The diagnosis of GH deficiency (GHD) in childhood is a multistep process involving clinical history, examination with detailed auxology, biochemical testing, and pituitary imaging, with an increasing contribution from genetics in patients with congenital GHD. Our increasing understanding of the factors involved in the development of somatotropes and the dynamic function of the somatotrope network may explain, at least in part, the development and progression of childhood GHD in different age groups. With respect to the genetic etiology of isolated GHD (IGHD), mutations in known genes such as those encoding GH (GH1), GHRH receptor (GHRHR), or transcription factors involved in pituitary development, are identified in a relatively small percentage of patients suggesting the involvement of other, yet unidentified, factors. Genome-wide association studies point toward an increasing number of genes involved in the control of growth, but their role in the etiology of IGHD remains unknown. Despite the many years of research in the area of GHD, there are still controversies on the etiology, diagnosis, and management of IGHD in children. Recent data suggest that childhood IGHD may have a wider impact on the health and neurodevelopment of children, but it is yet unknown to what extent treatment with recombinant human GH can reverse this effect. Finally, the safety of recombinant human GH is currently the subject of much debate and research, and it is clear that long-term controlled studies are needed to clarify the consequences of childhood IGHD and the long-term safety of its treatment.

Identification and management of poor response to growth-promoting therapy in children with short stature

Growth hormone (GH) is widely prescribed for children with short stature across a range of growth disorders. Recombinant human (rh) insulin-like growth factor-1 (rhIGF-1) therapy is approved for severe primary IGF-I deficiency - a state of severe GH resistance. Evidence is increasing for an unacceptably high rate of poor or unsatisfactory response to growth-promoting therapy (i.e. not leading to significant catch up growth) in terms of change in height standard deviation score (SDS) and height velocity (HV) in many approved indications. Consequently, there is a need to define poor response and to prevent or correct it by optimizing treatment regimens within accepted guidelines. Recognition of a poor response is an indication for action by the treating physician, either to modify the therapy or to review the primary diagnosis leading either to discontinuation or change of therapy. This review discusses the optimal investigation of the child who is a candidate for GH or IGF-1 therapy so that a diagnosis-based choice of therapy and dosage can be made. The relevant parameters in the evaluation of growth response are described together with the definitions of poor response. Prevention of poor response is addressed by discussion of strategy for first-year management with GH and IGF-1. Adherence to therapy is reviewed as is the recommended action following the identification of the poorly responding patient. The awareness, recognition and management of poor response to growth-promoting therapy will lead to better patient care, greater cost-effectiveness and increased opportunities for clinical benefit.

Association of the (CA)n repeat polymorphism of insulin-like growth factor-I and -202 A/C IGF-binding protein-3 promoter polymorphism with adult height in patients with severe growth hormone deficiency

OBJECTIVE

A number of mathematical models for predicting growth and final height outcome have been proposed to enable the clinician to 'individualize' growth-promoting treatment. However, despite optimizing these models, many patients with isolated growth hormone deficiency (IGHD) do not reach their target height. The aim of this study was to analyse the impact of polymorphic genotypes [CA repeat promoter polymorphism of insulin-like growth factor-I (IGF-I) and the -202 A/C promoter polymorphism of IGF-Binding Protein-3 (IGFBP-3)] on variable growth factors as well as final height in severe IGHD following GH treatment. DESIGN, PATIENTS AND CONTROLS: One hundred seventy eight (IGF-I) and 167 (IGFBP-3) subjects with severe growth retardation because of IGHD were studied. In addition, the various genotypes were also studied in a healthy control group of 211 subjects.

RESULTS

The frequency of the individual IGF-I (CA)(n) repeats ranging from 10 to 24, with the most frequent allele containing CA(19), was similar in controls and in IGHD subjects. However, in controls, the pooled CA(19) and CA(20) as well as -202 A IGFBP-3 alleles were significantly (P < 0·01 and P < 0·001) more common in the taller [≥2 to 0 standard deviation score (SDS)] when compared with the shorter subgroup (<0 to ≤-2 SDS). Overall, the effect of recombinant human growth hormone (rhGH) replacement did not reveal any difference between the various genotypes in terms of final height. Independent of their genotype, all subjects showed a slightly lower adult height SDS compared with midparental height SDS.

CONCLUSION

Our results indicate that in patients with severe IGHD, although the various IGF-I and IGFBP-3 genotypes may play a role in GH responsiveness, there was no effect on final height.

Diagnosis of growth hormone deficiency in childhood

PURPOSE OF REVIEW

The diagnosis of growth hormone deficiency (GHD) in childhood is challenging, in large part because of the lack of a true gold standard and the relatively poor performance of available diagnostic testing. This review discusses the recent literature on this topic.

RECENT FINDINGS

Auxology and clinical judgment remain the foundation for the diagnosis of GHD. Provocative growth hormone testing is poorly reproducible, dependent on factors such as body composition and pubertal status, and further limited by significant variability among commercially available growth hormone assays. Measurement of insulin-like growth factor I and insulin-like growth factor-binding protein 3 is not diagnostically useful in isolation but is helpful in combination with other diagnostic measures. Neuroimaging is also useful to inform diagnosis, as pituitary abnormalities suggest a higher likelihood of GHD persisting into adulthood. Although genetic testing is not routinely performed in the diagnosis of GHD at the present time, multiple recent reports raise the possibility that it may play a more important role in diagnosing GHD in the future.

SUMMARY

Beyond physicians' integrated assessment of auxology, clinical presentation, and bone age, current tools to diagnose GHD are suboptimal. Recent literature emphasizes the need to reappraise our current practice and to consider new tools for diagnosis.

Predicting response to growth hormone treatment

Despite extensive experience over the past 25 y in managing growth failure with growth hormone (rhGH), predicting treatment efficacy in individual children remains a challenge. In this paper, the authors present the methods that are currently available to clinicians for predicting the growth response, and other more sophisticated techniques which have the potential to pave the way for individualised therapy in the future.

Common polymorphisms in the GH/IGF-1 axis contribute to growth in extremely tall subjects

CONTEXT/OBJECTIVE

The growth hormone (GH)/insulin-like growth factor-1(IGF-1) axis is the key regulator of somatic growth in humans and its genes are plausible candidates to study the genetics of height variation. Here, we studied polymorphic variation in the GH/IGF-1 axis in the extremely tall Dutch.

METHODS

Case-control study of 166 tall cases with height >2 SDS and 206 controls with normally distributed height <2 SDS. Excluded were subjects with endocrine disorders or growth syndromes. We analyzed genomic DNA at 7 common polymorphisms in the GH-1, GH receptor (GHR), IGF-1 and IGFBP-3 genes.

RESULTS

The association of the GH-1 1663 SNP with tall stature approached statistical significance, with the T-allele more present in the tall (allele frequency (AF): 0.44 vs. 0.36; p=0.084). Moreover, haplotype frequencies at this locus were significantly different between cases and controls, with the GGT haplotype most commonly seen in cases (p=0.01). Allele frequencies of GHR polymorphisms were not different. For the IGF-1 CA-repeat we observed a higher frequency of homozygous 192-bp carriers among tall males compared to control males (AF: 0.62 vs. 0.55; p=0.02). The IGFBP-3 -202 C-allele occurred more frequently in cases than in controls (AF: 0.58 vs. 0.50; p=0.002). Within cases, those carrying one or two copies of the -202 C-allele were significantly taller than AA genotype carriers (AC, p=0.028 and CC, p=0.009). Serum IGFBP-3 levels were highest in AA genotype carriers, the -202 SNP explained 5.8% of the variation.

CONCLUSION

Polymorphic variation in the GH-1, IGF-1 and IGFBP-3 genes is associated with extremely tall stature. In particular, the IGFBP-3 -202 SNP is associated not only with being very tall but also with height variation within the tall.

Growth hormone pharmacogenetics: the interactive effect of a microsatellite in the IGF1 promoter region with the GHR-exon 3 and -202 A/C IGFBP3 variants on treatment outcomes of children with severe GH deficiency

Insulin-like growth factor type 1 (IGF1) is a mediator of growth hormone (GH) action, and therefore, IGF1 is a candidate gene for recombinant human GH (rhGH) pharmacogenetics. Lower serum IGF1 levels were found in adults homozygous for 19 cytosine-adenosine (CA) repeats in the IGF1 promoter. The aim of this study was to evaluate the influence of (CA)n IGF1 polymorphism, alone or in combination with GH receptor (GHR)-exon 3 and -202 A/C insulin-like growth factor binding protein-3 (IGFBP3) polymorphisms, on the growth response to rhGH therapy in GH-deficient (GHD) patients. Eighty-four severe GHD patients were genotyped for (CA)n IGF1, -202 A/C IGFBP3 and GHR-exon 3 polymorphisms. Multiple linear regressions were performed to estimate the effect of each genotype, after adjustment for other influential factors. We assessed the influence of genotypes on the first year growth velocity (1st y GV) (n=84) and adult height standard deviation score (SDS) adjusted for target-height SDS (AH-TH SDS) after rhGH therapy (n=37). Homozygosity for the IGF1 19CA repeat allele was negatively correlated with 1st y GV (P=0.03) and AH-TH SDS (P=0.002) in multiple linear regression analysis. In conjunction with clinical factors, IGF1 and IGFBP3 genotypes explain 29% of the 1st y GV variability, whereas IGF1 and GHR polymorphisms explain 59% of final height-target-height SDS variability. We conclude that homozygosity for IGF1 (CA)19 allele is associated with less favorable short- and long-term growth outcomes after rhGH treatment in patients with severe GHD. Furthermore, this polymorphism exhibits a non-additive interaction with -202 A/C IGFBP3 genotype on the 1st y GV and with GHR-exon 3 genotype on adult height.

Update in growth hormone therapy of children

Although recombinant human GH (rhGH) has been available since 1985, there are several questions related to its use that remain unanswered. The Entrez-PubMed search engine was used to conduct a review of publications appearing since 2007 that address growth and GH treatment. Recent publications related to the diagnosis of GH deficiency, genetics of growth, the use of rhGH in different genetic conditions, in idiopathic short stature, and in puberty, and strategies to adjust rhGH dose were reviewed. New studies investigating the genetics of growth and the response to rhGH therapy in different groups are helping in the understanding of the physiology of normal growth. Although in most children treated with rhGH there is a short-term benefit, the clinical relevance of the benefits after long-term treatment in some conditions remains unclear. The challenges are to define milder forms of GH deficiency and to assess the relevance of the benefits, if any, caused by rhGH in different patient populations and the best therapeutic approach for these patients. Well-designed long-term studies using anthropometric, genetic, and laboratory data that will also assess long-term quality of life benefits are needed to help clinicians select patients to initiate treatment with rhGH and to adjust treatment to improve outcome.

Genetic causes and treatment of isolated growth hormone deficiency-an update

Isolated growth hormone deficiency is the most common pituitary hormone deficiency and can result from congenital or acquired causes, although the majority of cases are idiopathic with no identifiable etiology. Known genes involved in the genetic etiology of isolated growth hormone deficiency include those that encode growth hormone (GH1), growth-hormone-releasing hormone receptor (GHRHR) and transcription factor SOX3. However, mutations are identified in a relatively small percentage of patients, which suggests that other, yet unidentified, genetic factors are involved. Among the known factors, heterozygous mutations in GH1 remain the most frequent cause of isolated growth hormone deficiency. The identification of mutations has clinical implications for the management of patients with this condition, as individuals with heterozygous GH1 mutations vary in phenotype and can, in some cases, develop additional pituitary hormone deficiencies. Lifelong follow-up of these patients is, therefore, recommended. Further studies in the genetic etiology of isolated growth hormone deficiency will help to elucidate mechanisms implicated in the control of growth and may influence future treatment options. Advances in pharmacogenomics will also optimize the treatment of isolated growth hormone deficiency and other conditions associated with short stature, for which recombinant human growth hormone is a licensed therapy.