Partial growth hormone insensitivity - idiopathic short stature is not always idiopathic

Saenger P. Partial growth hormone insensitivity - idiopathic short stature is not always idiopathic. Acta Pædiatr 1999; Suppl 428: 194–8. Stockholm. ISSN 0803–5326
Heterozygous growth hormone receptor (GHR) gene defects are not a common cause of idiopathic short stature. Although some of these GHR mutations may result in relative insensitivity to growth hormone (GH) in other studies, obligate heterozygotes did not present any clinical manifestations. Although patients with GH insensitivity and elevated GH binding protein (GHBP) levels have been described, it may be a reasonable approach to screen children who have growth failure, low levels of insulin-like growth factor-I (IGF-I) and IGF-binding protein-3, and low levels of GHBP. Whether the sensitivity of this screening approach can be increased by administering pharmacological doses of GH for a few days and measuring the resultant increase in serum IGF-I concentration remains to be determined by ongoing studies. □ Growth hormone insensitivity, growth hormone receptor, short stature     

Partial growth hormone insensitivity--idiopathic short stature is not always idiopathic

Heterozygous growth hormone receptor (GHR) gene defects are not a common cause of idiopathic short stature. Although some of these GHR mutations may result in relative insensitivity to growth hormone (GH) in other studies, obligate heterozygotes did not present any clinical manifestations. Although patients with GH insensitivity and elevated GH binding protein (GHBP) levels have been described, it may be a reasonable approach to screen children who have growth failure, low levels of insulin-like growth factor-I (IGF-I) and IGF-binding protein-3, and low levels of GHBP. Whether the sensitivity of this screening approach can be increased by administering pharmacological doses of GH for a few days and measuring the resultant increase in serum IGF-I concentration remains to be determined by ongoing studies.     

Partial growth hormone insensitivity

Partial growth hormone (GH) insensitivity can be defined as the clinical and biochemical features of IGF-I deficiency without GH deficiency and in the absence of the dysmorphic features of Laron syndrome. There is good evidence that this form of GH insensitivity exists, both in the context of severe GH resistance, and also in some patients with idiopathic short stature. The series of GH insensitivity patients in the European study shows a spectrum of clinical and biological defects, with several patients at the milder end of the spectrum having normal facies. The report of the presence of heterozygous mutations of the GH receptor in patients with idiopathic short stature has been confirmed by documentation of dominantly inherited mutations in familial short stature. Molecular screening in our unit of a group of 31 children with idiopathic short stature and normal GHBP, failed to identify mutations of the intracellular domain of the GH receptor. Consequently, although partial GH insensitivity is a proven entity, the clinical and biochemical identification of patients with GH resistance should precede molecular analysis. The analysis of individual patients and their families is more likely to reveal mutations, rather than a strategy of blanket molecular screening.     

Reduced insulin growth factor I concentrations in iron-overloaded beta thalassaemic patients with normal growth hormone secretion and liver function

We selected 92 subjects (46 females and 46 males), aged 10-15 years, from the Haematology and Endocrine Clinic of Shiraz University, Iran. Forty-six were beta thalassaemia patients (beta-Th) with short stature, 23 had idiopathic short stature (ISS) and 23 were healthy children with a standing height between the 10th and 95th percentile. Growth hormone (GH) secretion was normal in 23 beta-Th patients and reduced in the remaining 23 patients. A low insulin growth factor I (IGF-I) was found in 73.9% of beta-Th patients with GH deficiency, 56.5% of beta-Th patients with normal GH secretion to stimulation test and 8.7% of children with ISS. The reduced IGF-I concentration in beta-Th patients with normal GH secretion may be explained by partial insensitivity to GH (GHIS), neurosecretory dysfunction, low bioactive GH or increased proportion of circulating, non-22-kDa GH isoform. The possibility of GHIS in beta-Th patients with short stature indicates that higher doses of rechGH may be required to obtain an improvement in growth velocity in beta-Th patients.     

Idiopathic short stature

Idiopathic short stature (ISS) is a term used to describe the status of children with short stature that cannot be attributed to a specific cause. Many children diagnosed as having ISS have partial GH insensitivity, which can result from disturbances at various points of the GH-IGF-I axis. Several clinical studies on spontaneous growth in ISS showed that adult height was almost in the range of target height. GH treatment led to adult height not significantly higher than the pretreatment predicted adult height in most reports. No metabolic side effects have been observed, even when the dose was higher than in GH deficiency. Manipulation of puberty with gonadotrophin releasing hormone analogues reported by a few authors in a small number of children has shown conflicting results. Long-term psychological benefits of GH therapy for short normal children have not been demonstrated to date.     

Short stature caused by isolated SHOX gene haploinsufficiency: update on the diagnosis and treatment

Heterozygous SHOX defects are observed in about 50 to 90% of patients with Leri-Weill dyschondrosteosis (LWD), a common dominant inherited skeletal dysplasia; and in 2 to 15% of children with idiopathic short stature (ISS), indicating that SHOX defects are the most important monogenetic cause of short stature. In addition, children selected by disproportionate idiopathic short stature had a higher frequency of SHOX mutations (22%). A careful clinical evaluation of family members with short stature is recommended since it usually revealed LWD patients in families first classified as having ISS or familial short stature. SHOX-molecular analysis is indicated in families with LWD and ISS children with disproportionate short stature. Treatment with recombinant human growth hormone is considered an accepted approach to treat short stature associated with isolated SHOX defect. Here we review clinical, molecular and therapeutic aspects of SHOX haploinsufficiency.     

Insulin secretion in children with growth retardation

The effect of tolbutamide administration on insulin secretion was studied in 69 children with growth retardation. Diminished insulin secretion was found in all the patients, compared to the control group. This insulin deficit was most evident in patients with isolated, total GH deficiency and least evident in children with idiopathic short stature. Intermediate values were found in dwarfism due to isolated, partial GH deficiency.These results favour the hypothesis that hypoinsulinism contributes to the somatotropin deficiency in causing growth retardation.Abbreviations PD pituitary dwarfism - FSS familial short stature - GR growth retardation - GH growth hormone - ISS idiopathic short stature - tbt tolbutamide - GHtd isolated, total GH deficiency - GHpd isolated, partial GH deficiency     

Twelve-hour spontaneous nocturnal growth hormone secretion in growth retarded patients

Twelve-hour nocturnal GH secretion was studied in 30 children with familial short stature (FSS), constitutional growth delay (CGD), total growth hormone deficiency (TGHD), partial growth hormone deficiency (PGHD), or idiopathic short stature (ISS). No difference was observed between subjects with FSS and children with CGD. The mean 12-hour serum GH concentration was significantly lower in patients with TGHD (p less than 0.001), children with PGHD (p less than 0.01), and subjects with ISS (p less than 0.01) than in subjects with FSS and CGD. No overlap was observed between the range of mean concentration values of children with TGHD and that of subjects with FSS. A significant correlation was found between growth velocity expressed as SD from the mean for bone age and GH concentration (p less than 0.001). All patients with a growth velocity less than 3rd percentile for bone age showed a mean nocturnal concentration less than 4 ng/ml. These data suggest that evaluation of 12-hour spontaneous nocturnal GH secretion with GH sampling every 30 minutes can be usefully employed in the diagnosis of GH deficiency.     

Truncated growth hormone receptor isoforms

Ross RJM. Truncated growth hormone receptor isoforms. Acta Pædiatr 1999; Suppl 428: 164–6. Stockholm. ISSN 0803–5326
Truncated forms of the growth hormone receptor (GHR) that lack the majority of the cytoplasmic domain have been identified in a number of human tissues. In vitro , these truncated receptors act as dominant-negative inhibitors of the growth hormone (GH) signal and also generate large amounts of growth hormone binding protein (GHBP). Mutations that lead to high levels of expression of the truncated GHR are associated with short stature and GH insensitivity. Thus, truncated GHRs may be important as a physiological regulator of GH signalling in addition to providing a mechanism for the production of GHBR □ Cirrhosis, growth hormone, growth hormone insensitivity, growth hormone receptor, growth hormone resistance, truncated growth hormone receptor     

Insulin-like growth factor-I (rhIGF-I) therapy of short stature

The United States Food and Drug Administration (FDA) approved the use of subcutaneously injected rhIGF-I in late 2005 for treatment of children with severe short stature from growth hormone (GH) insensitivity due to genetic defects in the GH receptor or postreceptor mechanisms or from the development of GH inactivating antibodies. The approval was based on 15 years experience treating these rare conditions with rhIGF-I. Because of the very small numbers of children with these conditions, there has been an effort to justify and promote broader use for rhIGF-I. Attempts to identify GH unresponsiveness in children with idiopathic short stature (ISS) have yielded only a handful of patients with rare genetic disorders. IGF-I treatment for unequivocal GH insensitivity improves but does not correct growth failure, in contrast to the typical experience with GH replacement of GH deficiency. This emphasizes the importance of direct effects of GH at the growth plate, including the stimulation of maturation of cartilage precursor cells and local production of IGF-I, effects that cannot be duplicated by exogenous administration of rhIGF-I. Adverse effects testify to the more than adequate delivery of administered rhIGF-I to other tissues; these include lymphoid hyperplasia, coarsening of the facies, and increased percentage body fat. The absence of convincing evidence of GH insensitivity in a substantial number of children with ISS, the limited ability of endocrine IGF-I to restore normal growth in those with unequivocal GH unresponsiveness, the suppression of endogenous GH (and thereby, local GH effects on growth) that occurs with IGF-I administration, the risk profile, and the absence of data on efficacy in other than proven severe GH insensitivity, led the Drug and Therapeutics Committee of the Lawson Wilkins Pediatric Endocrine Society to conclude that rhIGF-I use is only justified in conditions approved by the FDA and that other growth promotional use should only be investigational. Nonetheless, substantial numbers of children are being treated with rhIGF-I off-label, exuberant estimates of potentially eligible patients are projected, and several uncontrolled clinical trials have been undertaken which are not based on sound preliminary data or established growth principles, and a single four-arm study begun comparing monotherapy with rhGH to combination rhGH with three dosages of rhIGF-I as a single daily injection, a means of administration of rhIGF-I that has not been tested.     

Isolated growth hormone deficiency in Chilean patients: clinical and molecular analysis

Isolated growth hormone deficiency (IGHD) is a disorder that leads to short stature. It has been classified into types IA, IB, II and III. GH gene mutations and growth hormone releasing hormone (GHRH) receptor gene mutations have been described in patients with IGHD. We report here a clinical and molecular study of 27 Chilean patients with IGHD. We performed GH stimulation tests with GHRH and GHRP, and segregation and molecular analysis of the GH, GHRH and GHRH receptor genes. We describe four patients with IGHD IA bearing a 7 kb mutation (13%), and two IGHD II patients who showed two different splice site point mutations (6.8%). In 21 patients, we did not find a mutation in any of the three genes examined. These results led us to conclude that the molecular causes of IGHD involve other genes besides those analyzed in this report, as has been reported previously in patients of different ethnic origins.     

Kleinwuchs und Therapie

Short stature is a diagnostic challenge because of the enormous spectrum of physiological maturation and growth patterns in childhood. A carefully drawn growth chart and calculation of the familial target height are required for a correct analysis. A low growth velocity, a height below the familial target, severe short stature and disproportionate or syndromic short stature are rational reasons for referral to a growth specialist. For clinical assessment a small for gestational age (SGA) patient history, presence of minor or major anomalies and skeletal disproportions should guide the diagnostic approach. Bone age estimation may enable the differentiation between inborn (primary) and acquired (secondary) growth failure. Growth hormone (GH) stimulation tests should only be performed if GH deficiency is very likely based on the foregone diagnostics. Constitutional delay of growth and puberty should not be confused with GH deficiency. A GH therapy is effective in GH deficiency and allows a normal growth within the familial target range in the majority of treated children. In addition, the diagnosis and therapy of Turner syndrome, SGA short stature and short stature homeobox-containing gene (SHOX) deficiency are discussed.     

Diagnostic Value of Growth Hormone-Releasing Hormone Tests in Short Children

Butenandt O. (Department of Paediatric Endocrinology, Children's Hospital, University of Munich, Munich, West Germany). Diagnostic value of growth hormone-releasing hormone tests in short children. Acta Paediatr Scand [Suppl] 349 93, 1989.
The growth hormone-releasing hormone (GHRH) test was applied to more than 230 children. Twenty-five out of 61 patients with proven growth hormone (GH) deficiency responded to GHRH with a GH increase of greater than 10 ng/ml. In most of the patients with idiopathic GH deficiency, a priming procedure using daily injections of GHRH improved the secretory response to GHRH. Nearly all children with familial shortness of stature showed a prompt increase in GH levels, with a mean peak level of 34.9 ng/ml (range 0.5–144 ng/ml). A second test was performed in five children with familial short stature because of failure to respond to the first test. Children with constitutional delay of growth and development did not differ in their GH response from patients with familial shortness of stature. Ten girls with Ullrich-Turner's syndrome responded with a mean increase of 22 ng/ml GH (range 10.1–34.0 nglml). Therapy with glucocorticoids, as well as endogenous hypersecretion of cortisol, suppressed the responsiveness of the pituitary gland to GHRH. Suppression was also observed following a single dose of dexamethasone during the steroid-suppression test in eight obese children. Low responsiveness of the pituitary gland was also seen in patients with thalassaemia and transfusion-induced haemosiderosis. It is concluded that it is not possible to detect GH deficiency with a single GHRH test. A full endo-crinological evaluation is necessary to prove the diagnosis.     

Truncated growth hormone receptor isoforms

Truncated forms of the growth hormone receptor (GHR) that lack the majority of the cytoplasmic domain have been identified in a number of human tissues. In vitro, these truncated receptors act as dominant-negative inhibitors of the growth hormone (GH) signal and also generate large amounts of growth hormone binding protein (GHBP). Mutations that lead to high levels of expression of the truncated GHR are associated with short stature and GH insensitivity. Thus, truncated GHRs may be important as a physiological regulator of GH signalling in addition to providing a mechanism for the production of GHBP.     

生长激素受体基因突变与非生长激素缺乏性矮身材的相关研究

目的了解生长激素受体（GHR）基因突变与非生长激素缺乏性矮小的相关性,以及GHR基因突变患儿的临床特点。方法（1）选择47例（男33例,女14例,年龄2—16岁）非生长激素缺乏而又显著矮小的患儿作为研究对象;80例身高正常的儿童（男49例,女31例,年龄1—17岁）作为对照组。（2）应用PCR-SSCP和基因测序技术检测GHR突变。（3）通过家系成员和正常对照人群的基因分析以及氨基酸同源序列分析等,推测突变基因的性质。结果（1）在47例矮小患儿中有5例、4种不同的GHR基因突变：H56R、G148E、IVS6-30,-31CA〉TG和IVS8＋10G〉C。5例患儿均为杂合突变,杂合突变个体的检出频率为10．6％（5／47）。（2）对照组的基因分析显示这些突变非多态性改变,初步认为H56R和G148E突变可能对蛋白功能产生影响。（3）确定了1种多态性突变：G168G（GGA〉GGG）。该位点基因频率的分布在矮小儿童组和正常对照组之间的差异无统计学意义,但与西方白种人之间的差异有统计学意义。提示该突变可能是单核苷酸多态性改变,与身高没有相关关系。但该位点的等位基因存在人种的差异。结论非生长激素缺乏性矮身材患儿存在GHR基因杂合突变。     

Genetic variants in the promoter region of the IGF-I gene as a reason for short stature

DNA obtained from the blood cells of 88 adolescent patients with short stature, with low blood serum IGF-I concentrations, normal growth hormone (GH) secretion and normal GH receptor (GHR) structure, was analyzed in the promoter region for the IGF-I gene. A total of 24 genetic variants was detected in the DNA of 13 patients. An attempt was also made to analyze the impact of identified mutations on DNA-protein interactions using EMSA.     

Adult height in children with idiopathic short stature treated with growth hormone

Idiopathic short stature (ISS) includes a heterogeneous group of patients with common characteristics to those of familial short stature and constitutional delay. Some authors state that these children can often respond to GH treatment, thus increasing their adult height. The aims of this study were to determine the effect of GH treatment (0.5-0.7 IU/kg/week) and the influence of some initial variables on adult height in patients with ISS. It was a non-randomized, observational study of 30 boys with ISS and a historical control group of 42 patients. The patients were followed until achieving their adult height. The mean height gain of the treated group attributable to GH was 4.5 cm. A stepwise regression model considering predicted adult height and target height as independent variables and final height as dependent variable gave an R2 coefficient of 0.38. We conclude that GH significantly increases final height in boys with ISS.     

The insulin-like growth factor I generation test in the investigation of short stature

Genotypic and phenotypic heterogeneity in patients with growth hormone (GH) insensitivity syndrome suggests that partial defects exist in the GH receptor. The insulin-like growth factor I (IGF-I) generation test was assessed as a means of identifying partial GH receptor defects in a heterogeneous group of 22 prepubertal children with short stature. In a subgroup of nine patients with peak GH levels of 63.7 ± 3.7 mU/l during a glucagon tolerance test, the response to the IGF-I generation test was no different from that for the group as a whole (peak GH, 43.3 ± 4.5 mU/l), despite the fact that this subgroup exhibited a negative relationship between height SDS and peak GH and a positive relationship between height SDS and IGF binding protein-3. This preliminary study therefore suggests that the IGF-I generation test in its present form will not be useful as a primary screening test for partial GH insensitivity. Despite this, the IGF-I generation test has been extremely useful in the confirmation of the diagnosis of GHIS and may therefore also prove useful in the confirmation of partial defects in the GH receptor. A subgroup of short children with peak GH levels above 40 mU/l had some characteristics of partial GH receptor deficiency. These children, to whom GH therapy would not normally be given, may respond better to recombinant human IGF-I.     

Idiopathic short stature: definition and treatment

Short stature is the leading cause of consultation in Pediatric Endocrinology. Decreased growth velocity and abnormally short height are characteristic of several different nosologic entities. Some are well characterized, while others correspond to what is known as idiopathic short stature (ISS). ISS includes children who grow less than 2 SD of the mean height values corresponding to their peers of similar age and the same sex, in whom the known causes of short stature have been ruled out. The diagnosis of ISS does not include children who only present a constitutional delay in growth and development. Several clinical trials have demonstrated the efficacy of growth hormone (rhGH) treatment in achieving catch-up growth in these children. Therefore, ISS should be kept in mind in the diagnosis of patients with short stature and abnormal growth patterns, who may benefit from rhGH treatment.     

Idiopathic Short Stature: Decision Making in Growth Hormone Use

Short stature is a common concern in pediatrics. Several ambiguities and controversies persist, especially with regard to criteria, cost, medical necessity and outcomes of growth hormone (GH) therapy for idiopathic short stature (ISS). Due to these ambiguities and controversies, a series of decisions by primary care physicians (whether to refer the short child to a pediatric endocrinologist), pediatric endocrinologist (whether to recommend GH treatment), families (whether to raise concern about short stature and whether to agree to undertake treatment), and third party payers (whether to cover the costs of GH therapy) influence which individual short children will receive GH in the US. Together, these decisions determine overall GH use. Apart from child’s growth characteristics, several non-physiological factors drive the critical decisions of these stakeholders. This article focuses on current ambiguities and controversies regarding GH therapy in ISS, discusses the decision-makers involved in GH therapy, and explores the factors influencing their decisions.