GH Gene Deletion Research Articles

Phenotype-Genotype Correlations of GH1 Gene Variants in Patients with Isolated Growth Hormone Deficiency or Multiple Pituitary Hormone Deficiency

Introduction: Genetic forms of growth hormone deficiency (GHD) may occur as isolated GHD (IGHD) or as a component of multiple pituitary hormone deficiency (MPHD). This study aimed to present the clinical and molecular characteristics of patients with IGHD/MPHD due to the GH1 gene variants. Methods: A gene panel accommodating 25 genes associated with MPHD and short stature was used to search for small sequence variants. Multiplex ligation-dependent probe amplification was performed in patients with normal panel results to investigate gross deletion/duplications. Segregation in the family was performed by Sanger sequencing. Results: The GH1 gene variants were detected in 5 patients from four unrelated families. One patient had IGHD IA due to homozygous whole GH1 gene deletion and one had IGHD IB due to novel homozygous c.162C>G/p.(Tyr54*) variant. Two patients from a family had previously reported heterozygous c.291+1G>A/p.(?) variant in which clinical and genetic characteristics were compatible with IGHD II accompanying MPHD. One patient had clinical and laboratory characteristics of IGHD II with MPHD but the heterozygous c.468 C>T/p.(R160W) variant had conflicting results about the relationship with the phenotype. Conclusion: Expanding our knowledge of the spectrum of GH1 gene variants by apprehending clinical and molecular data of more cases, helps to identify the genotype-phenotype correlation of IGHD/MPHD and the GH1 gene variants. These patients must be regularly followed up for the occurrence of additional pituitary hormone deficiencies.

Pathogenic and likely pathogenic genetic alterations and polymorphisms in growth hormone gene (GH1) and growth hormone releasing hormone receptor gene (GHRHR) in a cohort of isolated growth hormone deficient (IGHD) children in Sri Lanka

ObjectiveGenetic alterations in GH1 and GHRHR genes are known to cause isolated growth hormone deficiency (IGHD). Of these, GHRHR codon 72 mutation has been reported to be highly prevalent in the Indian subcontinent, but among Sri Lankans its prevalence was low compared to reports from neighboring countries. The present study was therefore carried out to identify genetic alterations in the GH1 gene and rest of the GHRHR gene in a cohort of Sri Lankan IGHD patients who tested negative for GHRHR codon 72 mutation. MethodsFifty five IGHD children negative for codon 72 (GHRHR) mutation were screened for gross GH1 gene deletion by polymerase chain reaction (PCR) and restriction fragment length polymorphism technique. The coding, intronic and promoter regions of the GH1 gene were sequenced in children who were negative for GH1 deletion (N=53). In a subset (N=40), coding, flanking intronic and promoter regions of the GHRHR gene were screened by single strand conformation polymorphism/sequencing. Identified coding region and intronic variants were subjected to in silico analysis to ascertain pathogenicity. Family members available were screened for the significant variants observed in the index child. ResultsGross GH1 gene deletions, 6.7kb and 7.0kb were observed in one child each. One novel and 24 reported single nucleotide variants (SNVs) were observed in the GH1 gene and its promoter. These included one reported pathogenic splice site mutation (c.172-2A>T) and one reported likely pathogenic missense mutation (c.406G>T). One large novel deletion of 5875 base pairs that included exon 1, one likely pathogenic novel SNV (c.211G>T) and 18 reported SNVs were observed in the GHRHR gene. Fourteen variants observed were of uncertain significance (8 in GH1 and 6 in GHRHR), twenty three variants were likely benign (11 in GH1 and 12 in GHRHR) and four variants were benign (4 in GH1 and none in GHRHR). ConclusionIn a cohort of IGHD children, six pathogenic or likely pathogenic genetic alterations of either GH1 gene or GHRHR gene were found. These affected a total of six children. Pathogenic status of four of these had been reported in the literature. Novel SNV in the GHRHR gene was predicted to be pathogenic through in silico analysis. The large novel deletion is likely to be pathogenic as it included exon 1 of GHRHR gene. Analysis of other genes will be needed to ascertain the genetic cause of IGHD in the remaining children.

Molecular Genetic Studies in Isolated Growth Hormone Deficiency (IGHD)

To screen Isolated Growth Hormone Deficiency (IGHD) patients with congenital Familial Isolated (FIGHD) and Nonfamilial Isolated Growth Hormone Deficiency (NFIGHD) for GH1gene deletions (6.7 kb,7.6 kb,7 kb) and Growth hormone releasing hormone receptor GHRHR(E72X) gene mutation and study genotype/phenotype correlation in this multicentre study. Clinical, auxologic (Ht.SDS ≤ -2.5), hormonal and MRI evaluation of hypothalamic/pituitary (HP) axis, IGF1, IGFBP3 estimation and GH stimulation test confirmed IGHD in 107 patients. Of these 107 patients, 97 consented for molecular genetic studies. Height, weight and Bone Age (BA) were obtained. PCR based restriction digestion method was used for molecular genetic analysis of patients and families. Ethics committee approval was obtained. Based on the genotype, these 97 patients (M60,F37;1.62:1) age 3 mo to 17 y belonging to 80 families (consanguinity, 15/80), were categorized into Group I with GH1 gene deletion, n = 17 (17.5 %) from 14 families, Group II with GHRHR (E72X) mutation n = 34 (35 %) from 24 families, Group III, n = 46 (47 %) from 42 families having neither of these deletions/mutations (but with sibling involvement). In Group I, homozygous 6.7 kb and 7.6 kb deletions involved 76 % and 18 %. 6.7 kb deletion with characteristic IGHD phenotype predominated in nonconsanguineous community from Rajasthan having lowest mean FBS (55.6 mg/dl, p < 0.001) and peak GH (0.03 ng/dl, p < 0.01). In Group II phenotype was IB. Twenty one of the 23 FIGHD had homozygous GHRHR(E72X) mutation and four with IGHD had heterozygous GHRHR(E72X) mutation. IGF1 and IGFBP3 were low. MRI showed hypoplastic anterior pituitary (APH) in all. Group III is not discussed in detail. Genetic background is more likely in congenital Growth Hormone Deficiency (GHD). GH1gene deletions and GHRHR(E72X) mutation with characteristic phenotypes are encountered in North Western region of India. Regional studies are essential.

Type IA isolated growth hormone deficiency (IGHD) consistent with compound heterozygous deletions of 6.7 and 7.6 Kb at the GH1 gene locus

Isolated growth hormone deficiency (IGHD) may result from deletions/mutations in either GH1 or GHRHR genes. The objective of this study was to characterize the molecular defect in a girl presenting IGHD. The patient was born at 41 weeks of gestation from non-consanguineous parents. Clinical and biochemical evaluation included anthropometric measurements, evaluation of pituitary function, IGF-I and IGFBP-3 levels. Molecular characterization was performed by PCR amplification of GH1 gene and SmaI digestion of two homologous fragments flanking the gene, using genomic DNA from the patient and her parents as templates. At 1.8 years of age the patient presented severe growth retardation (height 61.2 cm, -7.4 SDS), truncal obesity, frontal bossing, doll face, and acromicria. MRI showed pituitary hypoplasia. Laboratory findings confirmed IGHD. GH1 gene could not be amplified in samples from the patient while her parents yielded one fragment of the expected size. SmaI digestion was consistent with the patient being compound heterozygous for 6.7 and 7.6 Kb deletions, while her parents appear to be heterozygous carriers for either the 6.7 or the 7.6 Kb deletions. We have characterized type IA IGHD caused by two different GH1 gene deletions, suggesting that this condition should be considered in severe IGHD, even in non-consanguineous families.

Growth Hormone (GH-1) Gene Deletions in Children with Isolated Growth Hormone Deficiency (IGHD)

To detect growth hormone GH-1 gene deletions (6.7 kb, 7.6 kb, 7 kb) in familial/nonfamilial isolated growth hormone deficiency (IGHD) and note their clinical and investigative profile. Thirty (M16,F14) prepubertal IGHD patients aged 0.25 to 14 y, from 25 families were screened. Duration of growth failure, relevant history, clinical phenotype, and height SDS were recorded. Peak GH response to Clonidine (0.15 mg/m(2)), IGF-1, IGFBP-3 and pituitary/target gland hormones were studied. Genomic DNA of patients and family was analysed by PCR and DNA fragments were visualized on agarose gel electrophoresis. This series was divided into deletion +ve, Group I (n=12,40%) inclusive of six familial/six nonfamilial patients, and deletion -ve Group II (n=18,60%), 5 familial/13 nonfamilial cases; in total 11/30 were familial. Onset of growth failure was earlier in Group I (p<0.001) mean 1.1 vs 4.7 y. Mean height SDS was -7 vs. -4.5 in Groups I/II (p<0.01), age at presentation 5.1 vs 8.6 y. Overhanging forehead, prominent eyes, hypoplastic facies characterized Group I with FBS <50 mg/dl in 50% and very low peak GH <0.04 vs 2.04 ng/ml (p<0.001) in Group II. In both groups IGF-1 and IGFBP3 were low, other hormones were normal and MRI showed hypoplastic adenohypophysis. 40% had GH-1 gene deletion (6.7 kb deletion in 83%, 7.6 kb and a compound heterozygote in 8% each). In this series of 30 IGHD patients, frequency of GH-1 gene deletions (12/30) was 40%, and 54% among familial patients, and 31% with height SDS>-4. 83% had 6.7 kb deletion. Height SDS>-4, clinical phenotype, peak GH<1 ng/ml and hypoglycemia characterised IGHD Type IA.

Short stature and metabolic abnormalities in two sisters with a 7.6-kb GH1 gene deletion

Growth hormone 1 ( GH1) gene deletions occur in approximately 10–15% of patients with severe isolated, GH deficiency (GHD). The standard treatment for GHD is GH replacement. Individuals with GH gene defects, however, may form GH antibodies that interfere with the efficacy of exogenous recombinant GH (rhGH) therapy. Objective We describe the growth measures and metabolic studies of two Hispanic sisters with the same 7.6-kb GH1 gene deletion who presented with short stature and increased body fat, and who developed neutralizing GH antibodies secondary to rhGH exposure. Design The younger sister has now been treated with recombinant human insulin-like growth factor-I (rhIGF-I) for 4 years, and is continuing treatment. The older sister was not given rhIGF-I based on her normal height velocity and age. After the first 4 years of rhIGF-I treatment of the younger sister, we summarized the longitudinal anthropometric measures and serial laboratory studies, including GH surrogates, fasting lipid studies, oral glucose tolerance tests, and HbA1c, of both sisters. Body composition was quantified using DEXA analysis. Results The older sister achieved an adult stature at the low end of her mid-parental target height range, having been treated only with rhGH for ~ 2.5 years (between 11 months and 3.5 years of age). Treatment of the younger sister with rhIGF-I for 4 years has led to persistent improvement in height velocity, but was associated with adverse short-term effects on all lipids. Her BMI increased modestly (+ 4.1 kg/m 2) during rhIGF-I treatment, though her change in percent body fat was negligible by DEXA (Δ −0.7%). Conclusions In individuals with a GH gene deletion, rhIGF-I promotes increased height velocity, but may be associated with adverse effects on lipids and BMI. It is clear that the long-term effects of rhIGF-I on lipid metabolism and body composition require further monitoring and assessment with continued treatment.

Long-term auxological and pubertal outcome of patients with hereditary insulin-like growth factor-I deficiency (Laron and growth hormone-gene deletion syndrome) treated with recombinant human insulin-like growth factor-I

GH-IGF-I axis is mainly involved in the complex process of somatic growth but emerging evidence suggests that it also influences hypothalamic-pituitary-gonadal (HPG) function. We report some data regarding long-term auxological and pubertal outcome of five female patients with hereditary forms of GH-IGF-I deficiency (Laron and GH-gene deletion syndrome) and a mean age of 23.4±5.3 yr (range 19-32). All the patients received recombinant human IGF-I (rhIGF-I, Pharmacia and Upjohn, Stockholm, Sweden, and rhIGF-I, Genentech, San Francisco, CA, USA) from a mean age of 8.6 yr (range 3.2-14.2) up to the final height. Final height was very disappointing (≤ -5.0 SD scores) and lower than target height in all the patients. Pubertal onset was delayed in most of them but menarche occurred spontaneously in all the patients. Median age at menarche was 15.1 yr. Menstrual cycles were regular for several years. Median duration of gynecological follow- up was 8.3 yr with the longest span of 17.2 yr. We can assert that GH-IGF-I axis has an essential role in promoting linear growth in humans and its physiological action cannot be replaced by pharmacological treatment in most patients with hereditary forms of IGF-I insufficiency as demonstrated by their subnormal final height. Our clinical observations can also support an essential role of IGF-I in genitalia growth but not in the function of HPG axis as demonstrated by the maintenance of regular menstrual cycles in the presence of subnormal levels of IGF-I after treatment discontinuation.

Off-Label Use of Recombinant IGF-I to Promote Growth: Is It Appropriate?

Recombinant human (rh) IGF-I (mecasermin) was approved by the U.S. Food and Drug Administration (FDA) in 2005 for the orphan indication of severe primary IGF-I deficiency (IGFD) in individuals unresponsive to rhGH as a result of GH receptor or postreceptor defects or who have GH gene deletion with the development of GH inactivating antibodies after rhGH treatment. The clinical andbiochemicaldefinition includedheight SDscoreandbasal IGF-I SD score 3 or less, with normal or elevated GH. This indication applies to probably no more than a few hundred children worldwide, about 70 of whom provided the databasefortheFDAapproval (1).Therefore, it isnotunexpected that the manufacturer would promote the product beyond the orphan indication, dropping the severe qualification. “Approximately 1 million children in the United States have short stature, and we believe that there are an equal number of children with short stature in Western Europe. Of the approximately 380,000 children in the United States referred to pediatric endocrinologists for evaluation of possible short stature, we believe that approximately 30,000 in the United States and an equal number in Western Europe, for a total of 60,000 children, have primary IGFD and may be treated with (rhIGF-I)” (2). The clinical rationale for such off-label promotion of mecasermin, however, has been challenged (3). The comprehensive report by Midyett et al. (4) in the current issue of the Journal of Clinical Endocrinology and Metabolism provides important information about this approach. Described is one year of treatment of children with idiopathic short stature (ISS) thought to have partial defects in GH sensitivity resulting in IGFD, based on a single measurement of circulating IGF-I less than 2 SD for chronological age. The FDA approved the use of rhGH for the treatment of ISS in 2003, after nearly 20 yr of such use (5), a decision that has not been without controversy (6, 7). Nonetheless, there is considerable experience of improvement in adult stature with rhGH treatment of ISS (5, 8, 9). It is against this background of long and safe use of rhGH that the introduction of an alternative hormonal approach must be viewed. Considering the FDA approved use of rhGH for growth promotion in children with ISS and the potential limitations of simply enhancing endocrine IGF-I and suppressing GH secretion and thereby local GH effects of chondrocyte proliferation and autocrine/paracrine secretion of IGF-I (3), the design of a trial of rhIGF-I would be expected to include a rhGH treatment arm. The randomized,unblinded,no-treatment-controlled studyofMidyett et al. (4) is seriously limited by not including a rhGH comparator arm for safety and efficacy. Other concerns that have been previously expressed (3) and persist with this report include the use of a single IGF-I measurement as an inclusion criterion, the notion of partial GH insensitivity as justification for rhIGF-I treatment of a substantial number of children with ISS, absolute and relative efficacy (compared with rhGH or no therapy), and safety.

Insulin-Like Growth Factor-I Deficiency in Children with Growth Hormone Insensitivity

Growth hormone (GH) acts directly at the growth plate and through the production of insulin-like growth factor (IGF)-I. At least 50% of the hormone circulates bound to GH binding protein, and its secretion is controlled by growth hormone-releasing hormone and somatostatin. Once GH binds to two GH receptors, the janus activated kinase/signal transducers and activators of transcription (JAK/STAT) protein pathway is activated, resulting in the production of IGF-I. Serum IGF-I is produced predominantly in the liver and circulates in a 140 kDa complex, along with its binding protein, IGF binding protein 3, and acid-labile protein. Recombinant human (rh) IGF-I (mecasermin) is approved by the US FDA and the European Medicines Agency for the treatment of patients with severe primary IGF deficiency or for patients with GH1 gene deletion who have developed neutralizing antibodies to GH. It has been shown to increase growth velocity in children with either condition. In the past, there have been adverse events, particularly hypoglycemia, reported with the administration of mecasermin. However, a recent report of long-term therapy with mescasermin in children with severe IGF-I deficiency has concluded that although adverse events are common, they are rarely severe enough to interrupt or modify treatment. The serum half-life of mecasermin is shorter in patients with GH insensitivity syndrome and low serum levels of its binding protein, the insulin-like growth factor binding protein (IGFBP)-3 and acid-labile subunit, compared with the serum half-life in normal volunteers or in patients with an IGF1 gene deletion who have normal levels of IGFBP-3. Mecasermin rinfabate, a complex of rhIGF-I and rhIGFBP-3, appears to prolong the serum half-life and might counteract acute adverse events, particularly hypoglycemia, associated with the administration of mescasermin. Mecasermin rinfabate, however, is no longer available in the USA or Europe for treating conditions involving short stature, because of a legal requirement. Mecasermin has been shown to be effective in increasing height velocity and adult height in patients with severe GH resistance and in IGF1 gene deletion. There has been some interest in using mecasermin to treat patients with partial GH resistance or idiopathic short stature. At the present time, the data are insufficient to make this recommendation.

Nonalcoholic fatty liver in patients with Laron syndrome and GH gene deletion – Preliminary report

Background There is little information on the relationship between growth hormone/insulin-like growth factor-I (GH/IGF-I) deficiency or IGF-I treatment on nonalcoholic fatty liver disease (NAFLD) a disorder linked to obesity and insulin resistance. Objective To find out whether the markedly obese patients with Laron syndrome (LS) and GH gene deletion have fatty livers. Subjects We studied 11 untreated adult patients with LS (5M, 6F), five girls with LS treated by IGF-I and five adult patients with GH gene deletion (3M, 3F), four previously treated by hGH in childhood. Methods Fatty liver was quantitatively evaluated by ultrasonography using a phase array US system (HITACHI 6500, Japan). Body adiposity was determined by DEXA, and insulin resistance was estimated by HOMA-IR using the fasting serum glucose and insulin values. Results Six out of 11 adult patients with LS, two out of the five IGF-I treated girls with LS and three out of five adult hGH gene deletion patients were found to have NAFLD (nonalcoholic fatty liver disease). Conclusion NAFLD is a frequent complication in untreated and treated congenital IGF-I deficiency. No correlation between NAFLD and age, sex, degree of obesity, blood lipids, or degree of insulin resistance was observed.

Patients with congenital deficiency of IGF-I seem protected from the development of malignancies: A preliminary report

Objective Overexpression of IGF-I occurs in tumors diagnosed in childhood (osteosarcoma, Wilms tumor, neuroblastoma, etc.) and in adults (breast, ovaries, colon and prostate cancer). The aim of our study was to establish the prevalence of malignancies in states of congenital IGF-I deficiency. Subjects We surveyed 222 patients with congenital IGF-I deficiency (Laron syndrome, GH gene deletion, GHRH receptor defects and IGF-I resistance) and 338 first and second-degree relatives. Results None of the IGF-I deficient patients had cancer, whereas 9–24% of the family members had a history of malignancy. Conclusions Congenital IGF-I deficiency acts as a protecting factor for the development of cancer.

Clinical Characteristics, Etiologies and Pathophysiology of Patients with Severe Short Stature with Severe GH Deficiency: Questionnaire Study on the Data Registered with the Foundation for Growth Science, Japan

In this study, we sent questionnaires to doctors treating severe short stature with severe GH deficiency (GHD) (height SDS (HtSDS) below -4 and all peak GH to provocative stimuli below 2 micro/L) (abbreviated as Severe Case), and obtained effective replies of 51 cases. The clinical characteristics, etiologies, and pathophysiology of these patients were examined. Among the 51 Severe Cases no consanguinity was observed, 44 were IGHD (24 males and 20 females), 3 were GH-1 gene deletion, 2 were Pit-1 gene mutation, and 2 were achondroplasia. HtSDS in these Severe Cases was already remarkably low at 12 (-3.0) and 24 months old (-3.9), while their birth weight and birth length were within normal ranges. Among 44 patients with IGHD, 12 were isolated GHD, and the remaining 32 were combined pituitary hormone deficiency (CPHD). Pituitary MRI was undergone in 25 idiopathic GHD, and abnormal findings (pituitary atrophy, interruption of stalk, and ectopic posterior lobe) were observed in 21 patients with CPHD. More than half of these patients had the history of breech delivery. Three patients with GH-1 gene mutation showed normal pituitary MRI, whereas one of two patients with Pit-1 mutation showed pituitary atrophy and narrowing of pituitary stalk. In conclusion, Severe Cases tended to have CPHD, and the incidence of Severe Case was only 0.6% of total IGHD. Although GHD due to genetic disorders is considered to be extremely rare (0.06% of total IGHD), the incidence reaches high levels (9.8%) among Severe Cases. Growth disorders in these Severe Cases seem to occur soon after delivery. Much earlier diagnosis and hGH treatment are desirable to attain better final height in the Severe Cases. GH-1 and Pit-1 gene analyses are crucial, when genetic abnormalities other than achondroplasia are suspected.

Diabetic retinopathy, nephropathy and cardiovascular disease in a patient with GH gene deletion

Clinical EndocrinologyVolume 63, Issue 6 p. 699-700 Diabetic retinopathy, nephropathy and cardiovascular disease in a patient with GH gene deletion Zvi Laron, Zvi Laron Endocrinology and Diabetes Research Unit, Schneider Children's Medical Center, Petah Tikva, WHO Collaborating Center for the Study of Diabetes in Youth,Search for more papers by this authorDov Weinberger, Dov Weinberger Department of Ophthalmology, Rabin Medical Center, Beilinson Campus, Petah Tikva and Sackler School of Medicine, Tel Aviv University, Tel Aviv, IsraelSearch for more papers by this author Zvi Laron, Zvi Laron Endocrinology and Diabetes Research Unit, Schneider Children's Medical Center, Petah Tikva, WHO Collaborating Center for the Study of Diabetes in Youth,Search for more papers by this authorDov Weinberger, Dov Weinberger Department of Ophthalmology, Rabin Medical Center, Beilinson Campus, Petah Tikva and Sackler School of Medicine, Tel Aviv University, Tel Aviv, IsraelSearch for more papers by this author First published: 18 November 2005 https://doi.org/10.1111/j.1365-2265.2005.02402.xCitations: 5 Prof Zvi Laron, Endocrinology and Diabetes Research Unit, Schneider Children's Medical Center, Petah Tikva, 49202, Israel. E-mail: [email protected] Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat No abstract is available for this article.Citing Literature Volume63, Issue6December 2005Pages 699-700 RelatedInformation

Growth hormone and aging?

„The medicalization of old age is slowly entering the endocrine clinic and life-style medication for the affluent adult is about to enter the mainstream of endocrinology“. Intriguing new findings: Single gene mutations have been identified that lead to increased longevity. A highly conserved regulatory system for aging exists. Increased longevity of hypopituitary dwarf mice and GH resistant knockout mice appears to be in contrast with observations made in clinical practice. In humans, patients with a PROP-1 gene mutation can survive to a very advanced age, apparently longer than normal individuals in the same population. These findings may challenge the importance of GH as antiaging drug, and the notion that GH deficiency may shorten life span. On the other hand, reduced longevity in untreated patients with congenital isolated GH deficiency (GH-1 gene deletion) suggests that the lack of GH might have an impact on aging. Four retrospective studies and one prospective have all confirmed increased mortality in patients with hypopituitarism compared with age-matched controls, but the exact cause remains unclear due to the existence of limiting factors. There are no data whether or not GH replacement will prolong life expectancy. Somatopause and GH deficiency in elderly: Against a background of declining GH secretion and serum IGF-I with aging, clinical syndrome of GHD translates into profound changes in body composition and function. The GH Research Society consensus statement on the diagnosis of GHD, however, states that in adults, hypothalamic-pituitary disease must be present before the diagnosis of GHD can be considered. GH secretion in the patients with hypothalamo-pituitary disease is only 12%of that observed in the controls. Thus these patients can be distinguished from hyposomatotropism of ageing. Some studies (but not all) have reported rather convincing positive effects of GH replacement. GH replacement in elderly patients with organic GHD should be included in clinical consideration particularly when designing the individual replacement therapy. Changes in the functional activity of GHRH and somatostatin synthesizing neurons in the hypothalamus play a role in the age-related GH hyposecretion. In the last 10 years the unnatural growth hormone secretagogues (GHS) with the isolation of the endogenous ligand for the GHS-receptor, ghrelin, demonstrate the existence of a third physiologic system of GH regulation and raise the issue of the GHS/ghrelin function in aging. Very old subjects after combined, acute administration of saturating doses of GHRH and GHS, show GH response to be age-independent and fully preserved. Recently orally active GHS in healthy older men showed sustained GH increase for 2 yr. Overall these findings suggest that in aged individuals GH secretion may be restored by pharmacological means, based on the ability of GHSs to correct the attenuated GH pulsatility. The notion of „disease“ is a slippery one and health is equally impossible to define: Recent research efforts have focused on identifying mediators of debilitating processes or markers of poor health. Clinical studies linking catabolic cytokines, circulating levels of IGF-I, sarcopenia with mortality in very old community-dwelling men and women has shown that greater production of catabolic cytokines and reduced IGF-I levels are associated with increased mortality. In the Rotterdam study an association between a polymorphism of the IGF-I gene and total IGF-I serum levels, birthweight, body height and the risk for developing diabetes and cardiovascular diseases later on in life, has been found. Only homozygous carriers of the polymorphism of the IGF-I gene had an age-related and GH-dependent decline in circulating total IGF-I levels. Further research efforts should focus on identifying groups of patients in whom the risk of adverse effects is outweighed by the benefits achieved from GH treatment particularly in the elderly.

Growth hormone insensitivity: Physiologic and genetic basis, phenotype, and treatment

Primary growth hormone insensitivity is the absence of an appropriate growth or metabolic response to endogenous or exogenous growth hormone at physiologic concentrations, which is due to GH receptor deficiency or defective GH-GHR signal transduction. Numerous catabolic states and chronic conditions may demonstrate acquired GHI, but only that due to growth-inhibiting antibodies developing in patients with GH gene deletion who have been treated with GH has been considered, along with primary GHI, as appropriate for treatment with recombinant human insulin-like growth factor I. This review examines the physiology of the GH-IGF-I axis, noting the importance and varied actions of IGF binding proteins. Also considered is the classification and clinical and biochemical description of the conditions resulting in primary and acquired GHI and their similarity and differences from other IGF-I–deficient states. The molecular heterogeneity of primary GHI and the functional information certain mutations provide is discussed. A diagnostic sequence for these rare conditions is proposed, and the experience with rhIGF-I therapy in GHI is examined.

Hereditary isolated growth hormone deficiency caused by GH1 gene mutations in Japanese patients

Most patients with hereditary isolated growth hormone deficiency (IGHD) are either heterozygous or homozygous for a growth hormone (GH) gene abnormality. GH1 gene deletions (6.7 and 7.6 kb) from eight Japanese families with IGHD type IA has been detected by Southern blot analysis or polymerase chain reaction and Smal digestion. Heterozygous point mutations at the donor splice site of intron 3 in the GH1 gene have been identified among autosomal dominant IGHD type II patients. Recently, we have identified two kinds of splicing mutations in intron 3 in four Japanese families with IGHD type II. We believe a newly diagnosed G to A mutation at the fifth base of intron 3 in a Japanese family is responsible for the IGHD type II phenotype.

Clinical and molecular characterization of Brazilian patients with growth hormone gene deletions.

Genomic DNA from 23 patients with isolated growth hormone (GH) deficiency (12 males and 11 females: heights -4.9 +/- 1.4 SDS) was screened for GH gene deletions by restriction endonuclease analysis of polymerase chain reaction amplification products. Three unrelated patients had typical features of severe GH deficiency and deletions (6.7 kb in two and 7.6 kb in one) of the GH gene. The two patients with 6.7-kb deletions developed growth-attenuating anti-GH antibodies whereas the patient with the 7.6-kb deletion continued to grow with GH replacement therapy. Our finding that 3/23 (approximately 13%) Brazilian subjects had GH gene deletions agrees with previous studies of severe isolated GH deficiency subjects in other populations. Two of three subjects (67%) with deletions developed blocking antibodies despite administration of exogenous GH at low doses. Interestingly, only 1/10 of cases with affected relatives or parental consanguinity had GH-1 gene deletions.

Prevalence of human GH-1 gene alterations in patients with isolated growth hormone deficiency.

Human GH is encoded by the GH-1 gene which belongs to the GH gene cluster encompassing a distance of about 65 kb on the long arm of chromosome 17. Familial isolated growth hormone deficiency (IGHD) is associated with at least four Mendelian disorders. These include two forms that have autosomal recessive inheritance (IGHD types IA and IB) as well as autosomal dominant (IGHD type II) and X-linked (IGHD III) forms. The aim of our study was to evaluate the prevalence of all GH-1 gene alterations by sequencing the whole GH-1 gene after PCR amplification among 151 affected subjects from 83 families with severe IGHD (height: <-4.5 SD score). A high frequency of GH-1 gene alterations was found in families with IGHD type IA (8/12, 66.7%), whereas only a low frequency of GH-1 gene defects was present in all the other GH-deficient families (7/71, 9.9%). The absolute frequency of GH-1 gene deletions was 8.7% (6/69), 11.8% (4/34), and 18.7% (9/48) in Northern Europeans, Mediterraneans, and Asians, respectively, giving an overall frequency of 12.5% (19/151). The sizes of the deletions were heterogeneous with the most frequent (78%) being 6.7 kb. In addition, 6% (9/151) of the patients presented GH-1 gene mutations such as frameshift, stop codon and splicing error. Furthermore, total GH-1 gene abnormalities varied among different populations from 11.6% in Northern Europe, 14.7% in Mediterranean countries and 31.2% in Asia. Most striking, however, was the low frequency rate of 1.7% (2/119) of GH-1 gene mutations responsible for the most common phenotype of IGHD, namely type IB, among the subjects characterized by the production of deficient but detectable amounts of GH after provocative stimuli. This finding underlines the necessity to focus rather on the promoter region of the GH-1 gene (cis-acting elements and trans-acting factors), and on other candidate genes specific for the GH axis than the GH-1 gene itself to define genetically the IGHD type IB phenotype in more detail.

DUAL DEFICIENCY FOR GROWTH HORMONE AND INSULIN-LIKE GROWTH FACTOR-1.487

Severe dwarfism is found in:1) GH gene deletion with low serum GH and IGF-1 levels; normal growth occurs with recombinant human growth hormone (rhGH) therapy. 2) GH insensitivity syndrome (Laron's dwarfism) with GH receptor gene mutation, high serum GH and low IGF-1 levels; no growth occurs with rhGH therapy. These two disorders coexist in a 19 mo.old male with a height:67cm(-5.19 SD*), weight:5.9 Kg(-4.67 SD); head circum:45.5 cm (-1.89 SD). Basal and peak serum GH levels in response to L-dopa and Clonidine were: 0.8, 0.5 and 0.4, 0.9 ng/ml respectively. Bone age was 12 mo.at chronological age of 25mo. Treatment with rhGH at 0.1 mg/Kg three days a week was started at age 31 mo. with a height SD of -5.39; after 34 mo. posttreatment the height SD was -5.52.No improvement in growth velocity occurred when rhGH was given to the patient for 4 months in our pediatric clinic. During rhGH treatment, serum IGF-1 levels range from 3.5 to 17 ng/ml., IGFBP-3 was 0.2 ng/ml, and GHBP was 17 ng/ml. The failure of serum GH concentration to increase in response to provocative tests suggests GH gene deletion; while the lack of growth velocity, low IGF-1, low IGFBP-3 and low GHBP during rhGH treatment suggest an abnormality of the GH receptor resulting from deletion or point mutation of the gene for the GH receptor. These data provide evidence of a coexistence of a deficiency for GH and IGF-1 and makes this case unique.

Screening for growth hormone (GH) gene splice-site mutations in sporadic cases with severe isolated GH deficiency using ectopic transcript analysis.

We screened 10 children with sporadic severe isolated GH deficiency (IGHD) for GH-1 gene splice site mutations using ectopic transcript analysis. None had a history of birth trauma, congenital defects, thyroid disorders, or PRL deficiency. The mean age of these patients at diagnosis was 3.5 yr; the mean height at diagnosis was -4.0 SD score. GH-1 gene deletion was excluded in all cases. Ribonucleic acid (RNA) from lymphocytes was reverse transcribed and amplified by nested polymerase chain reaction, using two primer pairs with annealing sites within exons 2 and 5 of the GH-1 gene. The main polymerase chain reaction fragment obtained was 460 basepairs and proved to be the amplification of the GH-1 transcript. We also found three shorter fragments which were alternatively spliced GH-1 transcripts, including a variant devoid of the first 45 basepairs of exon 3, a second lacking the whole exon 3, and a third one, not previously described, lacking both exon 3 and exon 4. We found the same pattern of alternative splicing in RNA from GH-producing pituitary tumor tissue, which served as a positive control. In 1 of 10 patients, a pathologically shortened main fragment lacking exon 3 was detected. As proved by sequencing genomic DNA, this was the result of a heterozygous splice site mutation, with transversion from G to C of the first base of the donor splice site of intron III generating a new DdeI recognition site. The other allele had no mutation. DdeI digestion enabled us to rule out the defect in the parents' DNA. Thus, the mutation was de novo. As the patient with the mutation displayed the most severe and earliest growth retardation in the study group and had virtually no GH in serum, it must be assumed that the heterozygous genetic defect resulted in a dominant negative effect. The reason for this is still unclear. Recently, within a family that exhibited the autosomal dominant phenotype of IGHD (IGHD-II), a heterozygous point mutation was located 5 bases down-stream from that we describe here. A similar effect on splicing was observed. In conclusion, analysis of ectopic GH-1 transcripts enabled us to detect 1) a new alternatively spliced GH-1 messenger RNA variant lacking exons 3 and 4, and 2) 1 of 10 sporadic cases of severe idiopathic IGHD due to a heterozygous de novo splice site mutation in the GH-1 gene that changes G to C in the first base of intron III.(ABSTRACT TRUNCATED AT 400 WORDS)