X-linked congenital adrenal hypoplasia: new mutations and long-term follow-up in three patients

Mutations of the DAX-1 gene, which encodes a newly discovered member of the nuclear hormone receptor family, were reported to cause X-linked congenital adrenal hypoplasia and hypogonadotrophic hypogonadism. While genetic data on DAX-1 are accumulating, information on the clinical course of the disorder are scarce. Here we present a detailed documentation of longitudinal data relating to three cases. We retrospectively collected clinical data on three boys (6, 14 and 14.5 years old) who we examined over a period ranging between 5 and 14 years. Mutational analysis of the DAX-1 gene was performed by means of direct sequencing of PCR products. The patients presented at ages between 4 and 6 weeks with salt-wasting, but there was no evidence of hypoglycaemia. All three cases were initially erroneously diagnosed with isolated aldosterone deficiency. Glucocorticoid deficiency was established by means of ACTH stimulation tests at 4 months, 3 and 13 years of age. One boy, whose therapy was discontinued at the age of 4 months, developed normally until adrenal crisis occurred at the age of 13 years. In all three cases, congenital hypogonadism was ruled out during infancy, as penis size was normal, the testes were descended, and serum samples contained normal testosterone levels. One boy exhibited transient hypergonadotrophism at age 9 but showed no clinical signs of puberty or an increase in serum testosterone. Onset of puberty and LHRH tests proved to be normal in his case as well as in another patient studied. In two patients, genetic analysis revealed new mutations at the C-terminus of DAX-1, these being a 1-base deletion (656delG) inherited from the mother and a de-novo 2-base insertion (728insCA) of the DAX-1 gene, respectively, both causing frame shift and premature stops at codons 263 and 398. One boy was affected by a new nonsense mutation of codon 39 (W39X) inherited from his mother. Mineralocorticoid deficiency preceded glucocorticoid deficiency which could be diagnosed through ACTH stimulation after the neonatal period. Transitory functional recovery of the adrenal glands can occur in adrenal hypoplasia congenita (AHC). Transient hypergonadotrophism may be one of the first indicators of defects in the gonadal axis, although normal initiation of puberty is not rare. The definitive diagnosis was established by means of molecular analysis of the DAX-1 gene. There was no correlation between types of mutations and phenotypes. The diagnostic procedure in male children and adolescents presenting with adrenal crisis should include ACTH stimulation tests and mutational analysis of DAX-1 in the absence of another proven aetiology.

The somatotrophic system in patients with dilated cardiomyopathy: relation of insulin-like growth factor-1 and its alterations during growth hormone therapy to cardiac function

OBJECTIVE

Treatment with human recombinant growth hormone has yielded conflicting results in patients with congestive heart failure. In addition, growth hormone resistance has been reported in severe heart failure. Therefore, the purpose of this study was to evaluate the somatotrophic axis and effects of growth hormone on haemodynamics in patients with heart failure due to dilated cardiomyopathy.

DESIGN

Randomized, double-blind, placebo-controlled trial.

PATIENTS

Fifty clinically-stable patients with moderate heart failure (mean left ventricular ejection fraction = 26 +/- 2%) due to dilated cardiomyopthy were examined.

MEASUREMENTS

Patients were randomly assigned to treatment with placebo or 2 IU/d sc human recombinant growth hormone for a mean of 14 weeks. Cardiac size and function were evaluated by magnetic resonance imaging. Central haemodynamics were obtained by right heart catheterization. Measurements of plasma noradrenaline, serum insulin-like growth factor-1, and insulin-like growth factor binding protein-3 were performed by standard assays at baseline and at the end of the treatment period.

RESULTS

The severity of heart failure as determined by stroke volume, left ventricular end diastolic diameter and plasma noradrenaline concentrations correlated significantly to baseline serum insulin-like growth factor-1 levels (each P < 0.05). The growth hormone-induced increase of insulin-like growth factor-1 predicted the changes in ejection fraction (P < 0.05). A significant increase in ejection fraction of 7% was observed in patients whose insulin-like growth factor-1 increased by more than the median increase in comparison to the patients with an increase below the median (+ 4.0 +/- 2.3% vs. - 3.0 +/- 1.8%; P = 0.03).

CONCLUSIONS

Serum levels of insulin-like growth factor-1, reflecting growth hormone secretion, are diminished in relation to the severity of heart failure in patients with dilated cardiomyopathy. Growth hormone induced increases of insulin-like growth factor-1 of more than 77 ng/l caused significant improvement of ejection fraction.

Plasma concentrations of the carboxyterminal propeptide of type I procollagen (PICP) in preterm neonates from birth to term

Carboxyterminal propeptide of type I procollagen (PICP), a marker of bone formation, has not yet been studied in preterm infants. In this study, PICP concentrations were measured longitudinally for 12 wk after birth using the ELISA technique in 43 preterm infants with a gestational age (GA) ranging from 24-29 wk and in 35 preterm infants with a GA ranging from 30-34 wk. PICP values in these preterm infants were higher than in children and adults. In cord plasma of preterm infants there was a significant gender difference, with higher PICP concentrations in male infants. A characteristic longitudinal pattern with an initial decrease during the first 3 postnatal days followed by a rapid increase from d 7 to d 28 was seen in both groups. Regarding the individual gestational ages, all preterm infants attained maximum PICP concentrations around 36 wk postmenstrual age. Multiple regression analysis revealed cord plasma PICP concentrations were significantly associated with GA, birth weight, sex, and IGF-I. A significant correlation between PICP concentrations and GA was seen at wk 1-4 and between PICP concentrations and protein intake at wk 1. Body weight and energy intake were shown to exert a significant effect on the PICP concentrations at 2 wk. The collected data in preterm infants may serve further studies evaluating PICP as a marker for bone formation and growth in very low birth weight premature infants.

A rapid screening for steroid 21-hydroxylase mutations in patients with congenital adrenal hyperplasia. Mutations in brief no. 247. Online

Steroid 21-hydroxylase deficiency is the major cause of congenital adrenal hyperplasia (CAH). CAH due to 21-hydroxylase deficiency is divided into three classes: salt-wasting (classical), non-classical and simple virilizing, reflecting different degrees of clinical severity. Using polymerase chain reaction (PCR) and allele-specific oligonucleotide hybridisation (ASO), we screened the DNA of 62 Caucasian CAH families (heterozygous parents and children) for 14 different and frequently-found CYP21-mutations (HGMD). Of the 62 patients (21 males, 41 females), 26 females and 11 males had the classical or salt-wasting form, 3 females and 1 male had the non-classical form and 14 females and 7 males had simple virilizing CAH. More than 60% of the patients were compound-heterozygous. We found the mutations on 110 alleles (out of 124 alleles). There were 30 CYP21 gene deletions/conversions, 3 substitutions (P30L) in exon 1, 30 splice mutations (c.93-13A/C>G) in intron 2, 26 point mutations (I172N) in exon 4, one cluster of mutations (I236N, V237E, M239K) in exon 6, 8 mutations (V281L and 1760-1761insT) in exon 7, and 8 nonsense (Q318X) and 4 missense (R356W) mutations in exon 8. Our study supports the case for using this rapid technique for CAH-family screening as long as alleles from both affected patients and parents are screened in parallel.

Secretion of noncomplexed 'Big' (10-18 kD) forms of insulin-like growth factor-II by 12 soft tissue sarcoma cell lines

The paraneoplastic production of pro-insulin-like growth factor-II (IGF-II) forms causes tumour hypoglycaemias and presumably also has an effect on tumour cell growth. We investigated the molecular weights of IGF-II forms and their ability to form complexes with IGF binding proteins (IGFBPs) in conditioned culture media (CM) from 12 paediatric soft tissue sarcoma (STS) cell lines and from two healthy fibroblast lines. Untreated CM were separated by size exclusion chromatography using biocompatible HPLC. Subsequently, IGF-II, IGFBP-2 and IGFBP-3 were determined in the HPLC fractions by specific RIAs. In the CM, IGF-II concentrations between 0.5 and 8.6 ng/10(6) cells were measured but no IGF-I was detectable. Parallel to this investigation, a high IGF-II mRNA level averaging 44.4 +/- 29.7% was measured by semi-quantitative RT-PCR. The STS cell lines secreted a higher proportion of big-IGF-II forms reaching 10-18 kD (10-33% of the total IGF-II secreted) compared to the healthy fibroblasts (2.5-5%). At the same time, the proportion of IGF-II bound with IGFBP in complexes of 35- 70 kD and 150 kD was reduced by up to 85% in CM from tumour cells. The tumour cell lines apparently secrete a different spectrum of IGF-II forms than healthy fibroblasts. The reduced ability to form complexes with IGFBP and the higher molecular weight of the IGF-II forms produced by the tumour cells indicate that these forms could in fact be the known tumour-associated pro-IGF-II forms. Due to these characteristics, the big-IGF-II forms probably have an altered biological effect on the tumour cells when compared to IGF-II.

Influence of IGF-I and cell density on MDR1 expression in the T-lymphoblastoid cell line CCRF-CEM

The debate about a direct or indirect effect of GH and IGF-I on the recurrence of malignancy, especially in the case of rhGH therapy in patients with leukemia, is still going on. Recent studies suggested that IGF-I plays a role in drug resistance during anticancer therapy. This resistance to diverse cytotoxic drugs, named multidrug-resistance (MDR), is mainly due to high levels of P-glycoprotein (P-gp). The gene encoding this membrane-associated transporter protein was named MDR1, and increased levels of P-gp are linked to enhanced MDR1 mRNA expression. Our aim was to investigate a possible effect of rhIGF-I on MDR1 gene expression in vitro. We cultured the T-lymphoblastoid cell line CCRF-CEM with different rhIGF-I concentrations (0, 5, 20 and 50 ng/ml) in serum-free medium for 3 days. CCRF-CEM cells are drug-sensitive and express MDR1 at low levels. MDR1 mRNA expression was measured by semiquantitative RT-PCR using a competitive assay with a heterologous DNA construct. In addition, GAPDH mRNA was amplified as an internal control for RNA integrity. P-gp activity was determined by a flow cytometric assay measuring rhodamine 123 accumulation. Furthermore, cell proliferation was monitored in all experiments. Our data do not support an effect of rhIGF-I on MDR1 mRNA expression, P-gp activity or cell proliferation in the CCRF-CEM cell line. MDR1 mRNA levels were inversely correlated to cell density with high significance (p < 0.0001). In conclusion, multidrug resistance linked to P-gp is not induced by IGF-I in CCRF-CEM cells. At high density, CCRF-CEM cells downregulate MDR1 gene expression. Our experimental model provides a very useful tool for monitoring the influence of growth factors on multidrug resistance in vitro.

Should we treat children with idiopathic short stature?

The use of growth hormone (GH) to treat short children who are clearly GH-deficient is now well accepted. However, GH treatment of short children who have no currently recognizable abnormalities in their GH-insulin-like growth factor I axis remains controversial. Whether such children with so-called idiopathic short stature (ISS) should be treated with GH was the subject of an international workshop held in St.-Paul-de-Vence, France, in April 1999. This article summarizes the issues discussed at the workshop, including the definition of ISS, ethical and health-economic aspects of treatment, results from clinical trials and surveillance studies, and the use of prediction models in aiding treatment decisions.

Dosing of growth hormone in growth hormone deficiency

Growth hormone (GH) treatment of GH-deficient (GHD) children is to a certain extent standardized worldwide. Recombinant 22 kDa GH is injected once daily by the subcutaneous route, mostly in the evening. The amount of GH injected (calculated per kg body weight or body surface area, expressed in terms of IU or mg) in prepubertal children mimics the known production rate (approximately 0.02 mg [0. 06 IU]/kg body weight per day). However, there is a wide variation in dosage, the reasons for which are partly unknown and partly due to national traditions and regimes imposed by authorities regulating reimbursement. The situation during puberty is less standardized, with most clinicians still not increasing the dosage according to known production rates. The results of these approaches in terms of adult height outcome are not always satisfactory. In order to achieve optimal height development during childhood, puberty and adulthood, strategies must be developed to individualize GH dosing according to set therapeutical goals taking into account efficacy, safety and cost. The implementation of prediction algorithms will help us to reach these goals. In addition, other response variables will have to be monitored during treatment in order to correct for deficits resulting from GHD.

Symptomatic versus substitution growth hormone therapy in short children: from auxology towards a comprehensive multidimensional assessment of short stature and related interventions

There is an ongoing debate as to whether symptomatic growth hormone treatment (GHT) in short children without growth hormone deficiency (GHD) is justified, since there is no substitutional indication. The increasing evidence that final height cannot be normalized in these patients (e.g. in Ullrich-Turner syndrome) reinforces this controversy. We have focused on the empirical evidence on the psychosocial and physical meaning of being short in childhood as well as on the underlying assumptions of the different GHT indications. The indication for GHT in patients with non-GHD may be seen as a pharmacotherapeutic intervention in order to prevent the developmental, physical and psychosocial risks associated with short stature. This requires a qualitative shift in methodological assessment with respect to the psychosocial and physical impact of being short as well as of the potential benefit of new treatment indications in terms of a more comprehensive evaluation including health-related quality of life for these patients.

17alpha-hydroxylase/17,20-lyase deficiency as a model to study enzymatic activity regulation: role of phosphorylation

Cytochrome P450 17alpha-hydroxylase (CYP17) is a single gene-encoded protein with two activities: 17alpha-hydroxylase and 17,20-lyase. The two catalytic activities are differentially regulated in health and disease. We took advantage of naturally occurring human mutations to understand the molecular bases of this differential regulation. We identified eight novel mutations in the CYP17 gene, different in nature and spread throughout the gene. As posttranslational modifications appear to be important for activity control, we investigated the phosphorylation state of wild-type and mutant CYP17 proteins. Although phospholabeled protein was seen when the wild-type and most mutant proteins were expressed, no phosphorylation was detected for the F417C mutant. F417C is the only 17,20-lyase deficiency case confirmed at the molecular level and represents the first phosphorylation CYP17-deficient mutant. In search of the physiological agents involved in this process, the effect of cAMP was tested on activity and phosphorylation state of our mutant CYP17 proteins. cAMP stimulates activity and phosphorylation in all cases, except in the F417C and R35L mutants. The lack of response to the physiological second messenger might explain the different phenotypes. The F417C mutant protein, which is already shown to be associated with the lack of electron transfer, provides for the first time a link between the electron transfer system and the phosphorylation state of the CYP17 enzyme in the control of 17,20-lyase activity.

Incidence of diabetes mellitus and impaired glucose tolerance in children and adolescents receiving growth-hormone treatment

BACKGROUND

Growth hormone (GH) contributes to insulin resistance, but whether children treated with GH are at increased risk of diabetes has not been established. We undertook a retrospective analysis of data from an international pharmacoepidemiological survey of children treated with GH to find out the incidence of impaired glucose tolerance and types 1 and 2 diabetes mellitus.

METHODS

Reports to the survey of abnormal glucose metabolism were investigated and classified. The incidence and age-distribution of type 1 diabetes were compared with values from a model of reference data. The incidence of type 2 diabetes was compared with data from two reports of children not treated with GH.

FINDINGS

85 (0.36%) of 23333 children were reported with abnormal glucose metabolism. After investigation, 43 had confirmed glucose disorders (11 with type 1 diabetes, 18 with type 2 diabetes, and 14 with impaired glucose tolerance). The incidence and age at diagnosis of type 1 diabetes in children treated with GH did not differ from expected values. The incidence of type 2 diabetes was 34.4 cases per 100000 years of GH treatment which was six-fold higher than reported in children not treated with GH. Type 2 diabetes did not resolve after GH therapy was stopped.

INTERPRETATION

GH treatment did not affect the incidence of type 1 diabetes mellitus in any age group. We postulate that the higher than expected incidence of type 2 diabetes mellitus with GH treatment may be an acceleration of the disorder in predisposed individuals.

Role of nitric oxide in the vasodilator effect of recombinant human growth hormone in patients with dilated cardiomyopathy

OBJECTIVE

Dilated cardiomyopathy is characterized by elevated arterial vascular resistance and impaired nitric oxide (NO)-dependent vasodilation. Insulin-like growth factor-I (IGF-I) has been shown to stimulate endothelial NO-synthase resulting in endothelium-dependent vasodilation. Growth hormone (GH) substitution therapy leads in GH-deficient patients to significant increases of IGF-I which may alter systemic vascular resistance by stimulating NO production. This study was designed to evaluate the effects of treatment with recombinant human growth hormone (GH) on NO production and NO-dependent vascular effects in patients with dilated cardiomyopathy.

METHODS

50 patients with dilated cardiomyopathy were randomly assigned to double-blind treatment with 2 I.U. of GH or placebo for 3 months. Central hemodynamics were determined by Swan-Ganz catheter and cardiac output was obtained by the thermodilution method. Serum GH and IGF-I levels were measured and systemic NO production was determined from urinary nitrate and cyclic GMP excretion rates in 42 patients.

RESULTS

GH treatment caused in comparison to the placebo group a significant increase of IGF-I by 91 ng/ml (P = 0.0001). Urinary excretion rates of nitrate and cyclic GMP increased also significantly by 38 mumol/mmol creatinine (P = 0.027) and 65 nmol/mmol creatinine (P = 0.003), respectively. The parallel increase of both marker molecules indicates increased systemic NO production during GH treatment.

CONCLUSION

GH treatment induces a significant, but moderate increase of systemic NO production in patients with dilated cardiomyopathy. This effect may be mediated by IGF-I stimulating endothelial NO synthase.

New paradigms for growth hormone treatment in the 21st century: prediction models

Inconsistent and sometimes disappointing final height outcomes in studies in which exogenous growth hormone (GH) was given to children with short stature resulting from various causes have led to attempts to determine the factors that influence responsiveness to GH. Many such factors have been identified, including the genetically determined height potential of the child, the height deficit, current and perinatal auxological and biological factors, and, importantly, GH treatment modalities. These factors vary depending on the cause of the growth failure and during the course of childhood and treatment with GH. Data from well-defined large cohorts can be entered into multiple regression analyses to derive algorithms describing the variation in growth response during a defined period and the influence on this of various factors. Pharmacoepidemiologic surveys have been particularly useful in this regard. Algorithms with low-error SD values, which have included the dose of GH as a variable, can be used to predict the response to a putative GH dose in a similar cohort or in an individual over an equivalent period. A sequential series of such algorithms can be integrated to form a predictive model. Such a model can be used for planning a course of treatment, but the patient data required for entry into the model should be easily obtainable if the model is to have widespread utility. The development of such models will allow GH treatment to be better individualized and optimized for growth and cost outcomes. Growth prediction models will facilitate realistic expectations and will permit stepwise goals to be set and monitored.

Identification of short stature caused by SHOX defects and therapeutic effect of recombinant human growth hormone

Point mutations or complete deletions of SHOX, the short-stature homeobox-containing gene on the pseudoautosomal region of the sex chromosomes (Xp22 and Yp11.3), were recently reported in one family with idiopathic short stature and in several families with Leri-Weill syndrome (dyschondrosteosis). The missing SHOX is also thought to attribute to the growth failure in Turner syndrome. For testing the frequency of defects of SHOX in unexplained growth failure and recombinant human GH (rhGH) as a possible growth-promoting agent, we selected 68 children with idiopathic short stature. These probands had heights below -2.0 SD score for age, normal target heights, no significant bone age retardations, no endocrine abnormalities, no skeletal diseases, and no other organic diseases. No mutations were detected by single-strand conformational polymorphism analysis of the PCR-amplified SHOX. The analysis of three microsatellite DNA markers of the pseudoautosomal region, including one located on the 5' untranslated region of SHOX-exon 1, identified a 15-yr-old girl who carried a mutation in the form of a complete SHOX deletion. This girl who had a normal karyotype presented with mild mesomelic shortening of the forearms and lower legs. We treated two children with short stature on the basis of a SHOX point mutation (C674T) with rhGH at a dose of 1.0 IU/kg body weight-week in accordance with the regimen used in Turner syndrome. During the first 12 months of treatment, these two children (5.9- and 8.4-yr-old) showed an excellent growth spurt with a growth rate of 9.5 and 9.4 cm/yr, respectively. Growth of the lower extremities was weaker than in the trunk and arms. Our data suggest that short stature due to SHOX deletions is not a rare entity. Growth-promoting therapy with rhGH was effective with regard to height gain, but a tendency to disproportionate growth was apparent. In cases of unexplained growth failure, especially if associated with any mild skeletal disproportions, genetic analysis of SHOX should be considered.

Formation of uniparental disomy 7 delineated from new cases and a UPD7 case after trisomy 7 rescue. Presentation of own results and review of the literature

Maternal uniparental disomy for the entire chromosome 7 (matUPD7) has been reported several times in Silver-Russell syndrome (SRS) and growth-restricted patients. Here we present our results from the analysis of an abortion with confined placental mosaicism (CPM) for trisomy 7 which showed a maternal meiotic origin of the trisomy in the placenta and rescue to maternal UPD7 in foetal membrane. Furthermore, two newly detected SRS cases with maternal UPD7 revealed isodisomy and partial heterodisomy, respectively. Summarising these results with those published previously on the origin of UPD7, similar numbers of isodisomy (n=11) and cases with complete or partial heterodisomy (n=12) have been reported. In respect to the different formation mechanisms of UPD, complete isodisomy should be the result of a post-zygotic mitotic segregation error, whereas heterodisomic UPDs should be caused by trisomic rescue after meiotic non-disjunction events. In maternal UPD7, 50% of cases seem to be caused by post-zygotic mitotic segregation errors, which is similar to the situation in trisomy 7. This result corresponds to the situation in trisomy 8 but is in contrast to observations in the frequent aneuploidies. Thus, the different findings in these aberrations reflect the presence of multiple factors that act to ensure normal segregation, varying in importance for each chromosome.

Growth response to rhIGF-I 80 microg/kg twice daily in children with growth hormone insensitivity syndrome: relationship to severity of clinical phenotype

BACKGROUND

rhIGF-I has been used effectively to promote growth in growth hormone insensitivity syndrome (GHIS) in doses ranging from 40 microg/kg twice daily to 150-200 microg/kg once daily. It appears that the dose of 80 microg/kg twice daily s.c. may induce an equivalent response to higher doses with less side-effects.

OBJECTIVE

To study the efficacy and safety of rhIGF-I, 80 microg/kg twice daily s.c., in children with GHIS and to analyse the relationship of growth response to severity of phenotype.

PATIENTS AND DESIGN

Eleven prepubertal children (3 females, 8 males) with GHIS; basal GH > 2.5 microg/l, IGF-I < 50 microg/l, IGFBP-3 < - 2SD; were treated with IGF-I 80 microg/kg twice daily in a multi-centre study. The baseline characteristics of these patients were as follows (mean +/- SD): age, 7.5 +/- 2.5 years (range, 2.5-11.7 years), bone age (Tanner-Whitehouse - 2 RUS), 5.2 +/- 2.4 years (range, 2.3-9.1 years), mean height SDS, - 5.6 +/- 1.6 (range, - 3.1 to - 8.1), height velocity (HV), 3.1 +/- 1.1 cm/year (range, 1.9-4.9 cm/year). Height, HV, weight, skinfold thickness, puberty stage and bone age were measured at baseline and 6 monthly for 2 years.

RESULTS

During the first 12 months of IGF-I therapy, the mean +/- SD HV was 7.7 +/- 1.6 cm/year (range, 6.1-11.2 cm/year), the mean +/- SD increase in HV was 4.7 +/- 2.1 cm/year (range, 1.7-8.8 cm/year) and the mean +/- SD progression of bone age was 1.9 +/- 1.0 years (range, 0.8-3.8 years). Pre-treatment height SDS at the start of IGF-I therapy correlated positively with pretreatment serum IGFBP-3 SDS levels (r = 0.85; P < 0.01). There was a significant inverse correlation between gain in height SDS and pre-treatment height SDS (r = - 0.76; P < 0.01). During the 2nd 12 months of therapy, mean HV was 7.0 +/- 3.4 cm/year (range 3.8-12.4) change in height SDS from 12 to 24 months was not significantly correlated with pre-treatment height SDS. Subscapular skinfold SDS decreased significantly (P < 0.05) during the study period, whereas there was no significant change in body mass index and triceps skinfold thickness SDS. Adverse events reported in the patient group included headache (2 patients), hypoglycaemia (2 patients), papilloedema (transient, 1 patient), lipohypertrophy (5 patients) and tonsillectomy/adenoidectomy (2 patients).

CONCLUSION

This study reveals that IGF-I treatment at a dose of 80 microg/kg twice daily is effective in patients with growth hormone insensitivity syndrome. During the first 12 months of therapy, there was a significant inverse relationship between growth response to IGF-I therapy and the severity of the phenotype of growth hormone insensitivity syndrome, as measured by height SDS, at the start of therapy. Patients with a more severe clinical phenotype of growth hormone insensitivity syndrome, who also had most severe IGFBP-3 deficiency, responded better than those who were more mildly affected. An analogous situation has been shown to be the case in GH-deficient patients treated with hGH.

Predicting the response to recombinant human growth hormone in Turner syndrome: KIGS models. KIGS International Board. Kabi International Growth Study

A mathematical model for predicting the growth response in patients with Turner syndrome who received growth hormone (GH) therapy was developed by analysing data from KIGS, the Pharmacia & Upjohn International Growth Database. A model for year 1 of GH therapy explained 46% of the variability of the growth response, with GH dose being the most important of the predictors of height velocity. In years 2-4 of therapy, height velocity during the previous year was the most important predictor, suggesting that an individual's initial response to GH may determine the height outcome of treatment. Additional predictors of height velocity in years 1-4 of GH therapy included age (negative), weight SDS and additional treatment with oxandrolone. The predictions in all 4 years were highly accurate, as indicated by the low error SDs. However, relatively low predictive power (R) during years 2-4 of treatment suggests the models are missing other parameters that would explain more of the variability of the growth response. These growth prediction models could help clinicians to design individualized treatment regimens, provide realistic expectations of therapy outcomes, and adjust treatment on the basis of detected differences between observed and predicted height velocities.

Correlation of type I insulin-like growth factor receptor (IGF-I-R) and insulin receptor-related receptor (IRR) messenger RNA levels in tumor cell lines from pediatric tumors of neuronal origin

The insulin receptor-related receptor (IRR) is a member of the insulin receptor family. So far no ligand has yet been discovered for this receptor type (orphan receptor). IRR, insulin receptor (IR), and insulin-like growth factor-I receptor (IGF-I-R) are all tyrosine kinases. The cellular function of the IRR is not known. The expression of IRR mRNA is restricted to a few, e.g. neuronal tissues, and has also been found in neuroblastomas. Since tyrosine kinase receptors, including the IGF-I-R, may be involved in tumor genesis, we examined the expression of IRR mRNA and IGF-I-mRNA in 18 tumor cell lines using RT-PCR and the solution hybridization/RNAse protection assay. In particular, the mRNA levels of IRR and IGF-I-R were compared by semi-quantitative RT-PCR in seven neuroblastomas and 11 soft tissue sarcomas (STS), five of which were of neuronal origin. In all of the seven neuroblastoma cell lines and in five of the 11 STS cell lines, the IRR mRNA was detected. In addition, the IRR mRNA was expressed in rhabdomyosarcoma, in leiomyosarcoma, in one of the Ewing sarcoma and in the neurofibrosarcoma cell line. The last two tumor cell types are of neuronal origin. The levels of expression of IGF-I-R and IRR mRNA of the neuroblastoma cell lines were closely related (r = 0.82, P < 0.002). Furthermore, IRR mRNA was found only in cell lines that also expressed IGF-I-R mRNA. In conclusion, cell lines from pediatric tumors of neuronal origin express IRR mRNA simultaneously with a another tyrosine kinase receptor (IGF-I-R) mRNA. The tight coupling of their mRNA expression suggests a functional association of both receptors in the tumor cells.

Long-term treatment of growth hormone insensitivity syndrome with IGF-I. Results of the European Multicentre Study. The Working Group on Growth Hormone Insensitivity Syndromes

A total of 33 patients (17 female, 16 male) with Laron syndrome (n = 31) or hGH-1 gene (n = 2, type IA deletion) from 22 centres in 12 countries were enrolled in a study conducted by Pharmacia & Upjohn, Stockholm, which was designed to test the efficacy, in terms of growth promotion and safety, of IGF-I (Igef(TM)). The patients were treated with 40-120 microg/kg IGF-I s.c. twice daily after meals. After the study ended, the patients continued to be treated on an individual basis. The results of 17 patients, who were treated for 48 months or longer were available for the present analysis. Six patients were treated for up to 72 months. When treatment started, the mean age of these patients (8 female, 9 male) was 9.1 (3.7-13.5) years and mean height was -6.5 +/- 1.3 SDS. At the end of the observation period, the mean age of the 17 patients was 14.2 (9.1-17. 7) years and mean height was -4.9 +/- 1.9 SDS. All patients showed a significant increase in growth during the final year on IGF-I, with two of them reaching the age-corresponding 3rd centile. The total gain in height (DeltaHT) was 1.7 +/- 1.2 SDS. DeltaHT SDS correlated negatively with age at onset of treatment (R(2) = -0.78, p < 0.02). BMI was 0.6 +/- 1.8 SDS at start of treatment and 1.8 +/- 1.5 SDS at the end of observation. Total DeltaHT SDS correlated positively with total DeltaBMI SDS (R(2) = 0.59, p < 0.01). Long-term treatment of patients with GHIS thus proved to be effective in promoting growth. If treatment is started at an early age, there is considerable potential for achieving height normalisation. The treatment modalities need to be optimized with respect to the growth-promoting and metabolic effects of IFG-I.

Biparental expression of IGFBP1 and IGFBP3 renders their involvement in the etiology of Silver-Russell syndrome unlikely

Maternal uniparental disomy (UPD) of chromosome 7 has recently been reported in about 10% of Silver-Russell (SRS) patients. It can therefore be concluded that at least one gene on chromosome 7 is imprinted and mutations in this gene/these genes might contribute to the phenotype of the disease. Two genes which are involved in growth and localised in 7p12-13 are the insulin-like growth factor binding proteins 1 and 3 (IGFBP1; IGFBP3). Comparison to the mouse genome shows that the syntenic region on mouse chromosome 11 is imprinted, UPD of this region leads to deviations in growth in mice. In the present study we investigated whether the genes for IGFBP1 and IGFBP3 might be involved in the etiology of SRS: after exclusion of SRS specific mutations we could demonstrate biparental expression of both genes in lymphocytes of an SRS patient without UPD7 as well as expression in a patient with maternal UPD7. Our results as well as those from other groups show biparental expression of IGFBP1 in fetal tissues and expression of IGFBP3 in nearly every tissue during puberty and adult life. Thus, no evidence is given for an involvement of the two genes in SRS.

Variety in growth hormone determinations due to use of different immunoassays and to the interference of growth hormone-binding protein

More than 30 years after their introduction, growth hormone (GH) immunoassays showed the poorest inter-laboratory agreement of the various hormone assays evaluated in 1998 by the UK National External Quality Assessment Scheme, in which different laboratories using different assays reported that analyses of identical samples differed two- to threefold in value. There is therefore an urgent requirement and desire within the scientific community, particularly within centres diagnosing and treating GH deficiency and acromegaly, to resolve this problem and to develop a GH assay(s) that measures solely all of the relevant components of circulating GH immunoreactivity. The main confounders in the estimation of GH levels (now that the use of GH standards other than that recommended by the World Health Organization has largely been eliminated) are GH heterogeneity, anti-GH antiserum binding site specificity and interference from circulating high-affinity GH-binding protein (GHBP). The effects of these factors are closely related. The present study investigates these factors, focussing on the influence of GHBP and antibody binding site specificity on various assays for GH. The findings lead the authors to suggest that a solution to the problem may be to develop a GH assay that measures specifically and solely all serum 22 kDa GH, as this is the major circulating fraction and carries the dominant GH bioactivity.