Accuracy and self-validation of automated bone age determination.

The BoneXpert method for automated determination of bone age from hand X-rays was introduced in 2009 and is currently running in over 200 hospitals. The aim of this work is to present version 3 of the method and validate its accuracy and self-validation mechanism that automatically rejects an image if it is at risk of being analysed incorrectly. The training set included 14,036 images from the 2017 Radiological Society of North America (RSNA) Bone Age Challenge, 1642 images of normal Dutch and Californian children, and 8250 images from Tübingen from patients with Short Stature, Congenital Adrenal Hyperplasia and Precocious Puberty. The study resulted in a cross-validated root mean square (RMS) error in the Tübingen images of 0.62 y, compared to 0.72 y in the previous version. The RMS error on the RSNA test set of 200 images was 0.45 y relative to the average of six manual ratings. The self-validation mechanism rejected 0.4% of the RSNA images. 121 outliers among the self-validated images of the Tübingen study were rerated, resulting in 6 cases where BoneXpert deviated more than 1.5 years from the average of the three re-ratings, compared to 72 such cases for the original manual ratings. The accuracy of BoneXpert is clearly better than the accuracy of a single manual rating. The self-validation mechanism rejected very few images, typically with abnormal anatomy, and among the accepted images, there were 12 times fewer severe bone age errors than in manual ratings, suggesting that BoneXpert could be safer than manual rating.

Association analysis of ten candidate genes in a large multinational cohort of small for gestational age children and children with idiopathic short stature (NESTEGG study).

BACKGROUND: Fetal growth failure has been associated with an increased risk of hypertension, cardiovascular disease and diabetes in adulthood. Exploring the mechanisms underlying this association should improve our understanding of these common adult diseases. PATIENTS AND METHODS: We investigated 225 SNPs in 10 genes involved in growth and glucose metabolism (GH1, GHR, IGF1, IGF1R, STAT5A, STAT5B, MAPK1, MAPK3, PPARγ and INS) in 1,437 children from the multinational NESTEGG consortium: 345 patients born small for gestational age who remained short (SGA-S), 288 who showed catch-up growth (SGA-Cu), 410 idiopathic short stature (ISS) and 394 controls. We related genotype to pre- and/or postnatal growth parameters, response to growth hormone (if applicable) and blood pressure. RESULTS: We found several clinical associations for GH1, GHR, IGF1, IGF1R, PPARγ and MAPK1. One SNP remained significant after Bonferroni's correction: IGF1R SNP rs4966035's minor allele A was significantly more prevalent among SGA and associated with smaller birth length (p = 0.000378) and birth weight (weaker association), independent of gestational age. CONCLUSION: IGF1R SNP rs4966035 is significantly associated with birth length, independent of gestational age. This and other associations suggest that polymorphisms in these genes might partly explain the phenotype of short children born SGA and children with ISS.

Personalized approach to growth hormone treatment: clinical use of growth prediction models.

The goal of growth hormone (GH) treatment in a short child is to attain a fast catch-up growth toward the target height (TH) standard deviation score (SDS), followed by a maintenance phase, a proper pubertal height gain, and an adult height close to TH. The short-term response variable of GH treatment, first-year height velocity (HV) (cm/year or change in height SDS), can either be compared with GH response charts for diagnosis, age and gender, or with predicted HV based on prediction models. Three types of prediction models have been described: the Kabi International Growth Hormone Study models, the Gothenburg models and the Cologne model. With these models, 50-80% of the variance could be explained. When used prospectively, individualized dosing reduces the variation in growth response in comparison with a fixed dose per body weight. Insulin-like growth factor-I-based dose titration also led to a decrease in the variation. It is uncertain whether adding biochemical, genetic or proteomic markers may improve the accuracy of the prediction. Prediction models may lead to a more evidence-based approach to determine the GH dose regimen and may reduce the drug costs for GH treatment. There is a need for user-friendly software programs to make prediction models easily available in the clinic.

Functional and total IGFBP3 for the assessment of disorders of the GH/IGF1 axis in children with chronic kidney disease, GH deficiency, or short stature after SGA status at birth.

OBJECTIVE: IGFBP3 immunoreactivity may appear elevated in patients with chronic kidney disease (CKD), in part due to accumulation of low molecular fragments. The importance of these IGFBP3 variants for binding and inactivation of IGF1 and their relevance for the impaired growth of uremic children are unclear. Nevertheless, IGFBP3, measured as total (t-)IGFBP3, is frequently used as a diagnostic parameter in pediatric CKD patients. A new assay for functional (f-)IGFBP3 exclusively detects IGFBP3 capable of IGF binding. The aim of the study was to evaluate the significance of f-IGFBP3 measurements for the assessment of uremic abnormalities of the GH/IGF1 axis. DESIGN: Prospective cross-sectional study. METHODS: t-IGFBP3, f-IGFBP3, and IGF1 were measured in pediatric CKD patients, including patients with CKD stage 3-4 not on dialysis (CKD, n=33), on dialysis treatment (DT, n=26), patients after renal transplantation (RTx, n=89), healthy children (n=29), children with GH deficiency (GHD, n=42), and small for gestational age (SGA) children (SGA, n=34). RESULTS: Mean t-IGFBP3 SDS was elevated in CKD, DT, and RTx children compared with controls and GHD patients (P≤0.0004). Highest values were reached in DT (P<0.0001 vs all groups). In contrast, mean f-IGFBP3 was similar in all groups (P=0.30). CONCLUSIONS: Pediatric CKD patients displayed elevated serum concentrations of t-IGFBP3 but not f-IGFBP3, supporting the hypothesis that IGFBP3 fragments not binding IGF1 accumulate during uremia. f-IGFBP3 is an indicator of IGFBP3 fragmentation and seems to reflect IGF1 binding in CKD better than t-IGFBP3. However, the role of f-IGFBP3 for the diagnosis of disturbances of the GH/IGF hormonal axis appears to be limited.

Variants of the FTO gene in obese children and their impact on body composition and metabolism before and after lifestyle intervention.

OBJECTIVE: To investigate the impact of variants of the FTO gene (rs1421085, rs17817449, rs9939609) in obese children before and after lifestyle intervention. DESIGN: Longitudinal, clinical intervention study with an increase in physical activity, and nutritional recommendations based on the 'Optimized Mixed Diet for German Children and Adolescents' (Research Institute of Child Nutrition, Germany). STUDY POPULATION: 75 overweight children (40 male, mean BMI 30.4±5.5 kg/m², mean age 12.6±2.6 years). MEASUREMENTS: Genotyping by means of a TaqMan SNP genotyping assay. Lean and fat mass were determined by means of DXA. RESULTS: For the whole study population, the 6-month lifestyle intervention resulted in a significant improvement (before intervention minus time point 6 months; mean±SD) in BMI-SDS (0.10±0.17, p<0.001), HOMA (1.41±3.19, p<0.001) and relative fat-mass-SDS (0.09±0.23, p=0.005). Before and after lifestyle intervention, there was no significant difference between heterozygote (n=52) and homozygote (n=21) carriers of the FTO gene in terms of BMI, body composition, and the metabolic profile (Insulin, HOMA, lipids, liver function tests). CONCLUSION: Variants in the FTO gene are common in obese children but have no impact on body composition and metabolism before and after lifestyle intervention.

Impact of overweight on effectiveness of treatment with human growth hormone in growth hormone deficient children: analysis of German KIGS data.

BACKGROUND: We hypothesized that overweight children with growth hormone deficiency (GHD) demonstrate a lower response to growth hormone (GH) as a result of a misclassification since obesity is associated with lower GH peaks in stimulation tests. METHODS: Anthropometric data, response, and responsiveness to GH in the first year of treatment were compared in 1.712 prepubertal children with GHD from the German KIGS database according to BMI (underweight=group A, normal weight=group B, overweight=group C) (median age: group A, B, C: 7.3, 7.28, and 8.4 years). RESULTS: Maximum GH levels to tests (median: group A, B, C: 5.8, 5.8, and 4.0 µg/ml) were significantly lower in group C. IGF-I SDS levels were not different between the groups. Growth velocity in the first year of GH treatment was significantly lower in the underweight cohort (median: group A, B, C: 8.2, 8.8, and 9.0 cm/yr), while the gain in height was not different between groups. The difference between observed and predicted growth velocity expressed as Studentized residuals was not significantly different between groups. Separating the 164 overweight children into obese children (BMI>97th centile; n=71) and moderate overweight children (BMI>90th to 97th centile, n=93) demonstrated no significant difference in any parameter. CONCLUSIONS: Overweight prepubertal children with idiopathic GHD demonstrated similar levels of responsiveness to GH treatment compared to normal weight children. Furthermore, the IGF-I levels were low in overweight children. Therefore, a misclassification of GHD in overweight prepubertal children within the KIGS database seems unlikely. The first year growth prediction models can be applied to overweight and obese GHD children.

Short children with low birth weight born either small for gestational age or average for gestational age show similar growth response and changes in insulin-like growth factor-1 to growth hormone treatment during the first prepubertal year.

BACKGROUND/AIMS: Growth hormone (GH) is an accepted treatment for short children born small for gestational age (SGA). The aim of this analysis was to compare the growth response to GH in children with low birth weight born SGA or appropriate for gestational age (AGA). METHODS: This retrospective observational study is from one center. Of all the children with a birth weight <2,500 g treated, 50 were primarily diagnosed as having growth hormone deficiency ([A] SGA, n = 26; [B] AGA, n = 24) and 138 were originally diagnosed SGA or AGA (reclassified: [C] SGA, n = 102; [D] AGA, n = 36). RESULTS: [Median; A, B, C, D]: at an age of 4.9, 5.2, 5.8, 5.8 years, a height of -2.9, -2.4, -2.8, -2.9 SDS and a GH dose of 27, 28, 41, 39 µg/kg/day, the children grew 0.9, 0.9, 0.8, 0.9 SDS in height, respectively. Insulin-like growth factor-1 (IGF-1) at GH start was, respectively, -2.1, -2.2, -0.4, -0.9 SDS and rose to (delta IGF-1) 1.8, 2.0, 1.7, 1.5 SDS during the first year on GH. All differences were not significant. CONCLUSIONS: We show for the first time that short stature children with low birth weight born AGA experience the same increase in height and IGFs to GH treatment as those born SGA irrespective of actual GH secretory status.

The functional muscle-bone unit in obese children - altered bone structure leads to normal strength strain index.

UNLABELLED: Obese children have a twofold increased risk of fracture of the forearm compared to non-obese children. OBJECTIVE: To investigate bone strength and bone structure of the forearm, and the relationship between muscle and bone in obese children. METHODS: The study-group consisted of 84 (40 female) overweight children (mean (SD)) age 11.8 (3.2) years, BMI 29.0 (5.1) kg/m(2)). Bone geometry and strength were measured at the proximal radius of the non-dominant forearm (65% measurement site) by means of pQCT (XCT 2000). Bone mineral density and lean mass of the total body was determined by means of DXA (Lunar, DPXL/PED). Results were compared to reference values by calculating age (SDS(CA)) and height-age (SDS(HA)) dependent standard deviation scores (SDS). RESULTS: Cortical density, -1.11 (1.74) SDS(HA), -0.45 (1.52) SDS(CA); cortical thickness, -1.46 (1.33) SDS(HA), -1.01 (1.46) SDS(CA); cortical area, -0.42 (1.31) SDS(HA), 0.26 (1.58) SDS(CA); total bone area +2.21 (1.47) SDS(HA), 2.91 (1.80) SDS(CA), marrow area +3.12 (2.29) SDS(HA), 3.37 (2.38) SDS(CA); strength strain index +0.10 (1.10) SDS(HA), 0.95 (1.57) SDS(CA). These changes in bone structure were independent from pubertal stage. Measurements revealed correlations between muscle area and SSI (R(2)=0.67, p<0.001), and muscle mass and bone mineral content (DXA; R (2)=0.81, p<0.001). CONCLUSION: Low cortical density, normal cortical area and increased total bone area led to a normal strength strain index adjusted both for height and for age. We assume that this normal bone strength is not appropriate for the higher kinetic energy of impact in case of a fall in overweight children.

Metacarpal thickness, width, length and medullary diameter in children--reference curves from the First Zürich Longitudinal Study.

SUMMARY: Metacarpal thickness (T), width (W), length (L) and medullary diameter (M) were measured in 3,121 X-rays from 231 healthy Caucasian children aged 3 to 19 years and analysed for bone age, age, height, weight and gender-related characteristics, showing highly differentiated growth patterns with prepubertal dips. Reference data for the four metacarpal measures are presented. INTRODUCTION: The aim of the study was to create and explore a reference database for metacarpal T, W, L and M in children. METHODS: Three thousand one hundred twenty-one left-hand X-rays (1,661 from boys) from 231 healthy Caucasian subjects (119 boys) aged 3 to 19 years were analysed by BoneXpert, a programme for automatic analysis of hand X-rays and bone age (BA; in years). RESULTS: In boys, growth of T, W and L shows a prepubertal decrease from BA 7 to 13 and then accelerates again. In girls, the same is seen only for T starting from BA 8 to 11, whereas W and L grow at a declining rate. M shows steady growth until BA 10.5 in girls and BA 13.5 in boys and then grows smaller in both. W is greater in boys from BA 6 onwards, while L is greater in girls from BA 9 to 13 and T from BA 11 to 14. BA is reflected best by L until start of puberty and by T and L thereafter. CONCLUSION: T, W, L and M show highly differentiated growth patterns. These reference data provide a basis for further research into skeletal development and the management of hormone therapies in children.

Investigation of myostatin serum levels before and after a 6-month lifestyle intervention program in obese children.

OBJECTIVE: To investigate the relationship between myostatin serum levels and muscle mass, fat mass and HOMA before and after a 6-month lifestyle intervention program in obese children and adolescents. DESIGN: A total of 57 overweight children and adolescents (female, n=27; age range, 6.0-16.1 years) were examined between 2007 and 2009. Mean BMI (±SD) was 31.1 (5.7) kg/m(2) corresponding to a mean BMI-SDS LMS of 2.2 (0.4). Muscle and fat mass were determined by means of DXA. Serum myostatin was measured by using a competitive ELISA. RESULTS [MEAN±SD]: After the 6-month intervention program, muscle mass (+2.1±2.7 kg, p<0.0001), and percentage myostatin serum levels (+23.7±26.7%, p<0.0001) were higher than before, whereas decreases in BMI (-0.4 kg/m(2)±1.5, p<0.0001), fat mass (-1.2±3.9 kg, p<0.0001), and HOMA insulin sensitivity index (-0.78±3.28 SD, p=0.0004) were observed. In 86% (n=49, p<0.0001) of all cases, the intervention program resulted in a higher level of myostatin. After lifestyle intervention, patients with the greatest increase of myostatin had a significantly lower increase of muscle mass (p=0.048) but did not differ for fat mass. There was no significant correlation between Myostatin and HOMA insulin sensitivity index before and after lifestyle intervention. CONCLUSION: Both muscle mass and serum myostatin increased concordantly. Patients with the greatest rise of myostatin had a significantly lower increase of muscle mass suggesting a negative feedback loop between myostatin and muscle tissue. In our study, the change of myostatin serum levels was not associated with the amount of fat mass or HOMA insulin sensitivity index.

Validation of functional insulin-like growth factor binding protein-3 measurement by a ligand immunoassay.

BACKGROUND: Proteolysis of Insulin-like Growth Factor Binding Protein (IGFBP)--3 is a well known mechanism regulating IGF-I bioavailability and IGF-independent actions of IGFBP-3 fragments. Measurement of functional IGFBP-3 can be of use in diagnostics of growth failure or renal impairment. We herein characterize the properties of a commercially available immunoassay for the measurement of functional (IGF-I binding) IGFBP-3. METHOD: Fragmentation of IGFBP-3 is analyzed by gel filtration, SDS-PAGE, and western ligand and immunoblotting and compared with subsequent measurement of total and functional IGFBP-3 by ELISA/IFA. Furthermore, assay characteristics such as reproducibility, linearity, and sensitivity are surveyed. RESULTS: Functional IGFBP-3 was reproducibly measured (6.8/5.6% Inter-/Intra assay variance). A broad range of linearity (1:50-1:300) and a high sensitivity (0.18 microg/L) allowed reliable measurement of IGF-binding IGFBP-3. Analysis of IGFBP-3 fragments reveals that the assay described only detects intact IGFBP-3. Analysis of 189 serum samples from healthy blood donors showed that on average 84% and 69% of total IGFBP-3 was functional in men and women, respectively (p < 0.01). CONCLUSIONS: Functional IGFBP-3 can be measured reliably by the assay system used. Thus, this assay system is suited for the investigation of the diagnostic value of functional IGFBP-3 in human body fluids.

Prevalence and incidence of endocrine disorders in children: results of a survey in Baden-Wuerttemberg and Bavaria (EndoPrIn BB) 2000-2001.

BACKGROUND: Sparse data is available on the incidence of endocrine disorders among children in Germany. AIM: A pioneer study was established to analyse, in the German states of Baden-Wuerttemberg (BW) and Bavaria (BY), the incidence and prevalence of congenital adrenal hyperplasia (AGS; CAH), precocious puberty (PP), primary congenital hypothyreosis (PCH), Graves disease (MB), and growth disorders related to the Ullrich-Turner syndrome (UTS) and growth hormone deficiency (GHD). METHODS: Participation in the study involved each paediatric hospital in BW and BY (n = 63),and all regional paediatricians belonging to the Association of Statutory Health Insurance Physicians (SHI) practising in these states (n = 1 443). Data collection was done from January 1, 2000, to December 31, 2001, and included all patients in the 0- < 18 age range. RESULTS: Completeness of data was 81 % for CAH and 55 % for UTS (capture-mark-recapture method).The incidence rate (IR, per 100 000 / year)versus prevalence rate (per 100 000 at the time point December 31, 2001) was: CAH 0.64 vs.9.60; PP 2.42 vs. 10,85; PCH 1.88 vs. 14.97; MB 0.89 vs. 3.25; UTS 2.15 vs. 29.07; and GHD 3.47(IR). Among neonates, the incidence of CAH was 1 / 7 794; PCH 1 / 2 629 and UTS 1 / 2 300. CONCLUSIONS: A pioneer study has been established in Germany for investigating the frequency of AGS (CAH), PP, PCH, MB, UTS, and GHD among children and adolescents. Our data shows that these disorders occur in approx. 2,700 children per year in total Germany, and about 12 000 of these children need to be treated in specialized paediatric endocrinological centres.

Is the response to growth hormone in short children born small for gestational age dependent on genetic or maternal factors?

BACKGROUND/AIMS: We investigated whether genetic or maternal/environmental risk factors for being born small for gestational age (SGA), e.g. Silver-Russell syndrome, congenital heart defects, infections of mothers or smoking during pregnancy, explain the variation in the first-year growth response to GH therapy. METHODS: Secondary analysis was made of growth response in 135 short prepubertal German children (66% males) enrolled in a SGA phase III trial. Initial mean patient age was 6.8 +/- 2.6 years; mean patient height SDS -3.8 +/- 1.2, and GH treatment dose was 0.066 mg/kg body weight per day. RESULTS: Growth velocity increased by 4.5 +/- 2.0 cm/year and height SDS by 1.0 +/- 0.5 SDS. Although patient number was limited and variation was high, both growth response (cm/year) and change in height SDS did not appear to differ between subgroups which also did not differ in terms of Studentized residuals set up in the KIGS growth prediction model for SGA. Likewise, in a step-forward multivariate analysis, the variables Silver-Russell syndrome, congenital heart defects, infections of mothers and smoking were not identified as independent factors influencing growth velocity. CONCLUSION: The retrospectively analyzed genetic and maternal/environmental risk factors for SGA do not appear to explain the observed patient variance in response to GH. Larger prospective studies are needed, however, to substantiate these preliminary findings.

[Considerations of growth hormone treatment during the transition from adolescence to adulthood]. / Besonderheiten bei der Behandlung mit Wachstumshormon während des Ubergangs vom Jugendlichen zum Erwachsenen (Transition).

Growth hormone (GH) replacement treatment in adults with severe growth hormone deficiency is based on its known effects on body composition, physical performance, bone and lipid metabolism, and on improvements in the quality of life. These features must be taken into consideration when planning GH treatment of patients who are in the transition phase (aged between 15 and 25 years), because developmental stages may vary. GH deficiency during the transition phase is defined as GH levels under 6 microg/l in a standard stimulation test, compared to < 10 microg/l during childhood and < 3 microg/l during adulthood. We present an overview of the diagnostic strategies recommended at international consensus conferences on the verification of GH deficiency during the transition phase. In analogy to the GH treatment of adults, the dosaging (dose at start = 0.2 - 0.5 mg/day) should be based on individual requirements as well as IGF-I concentrations in blood (> 1.0 SDS or < 2.0 SDS). GH treatment during the transition phase should be monitored by an endocrinologist with expertise in dealing with adolescent and adult patients, as well as having experience in structuring treatment and documentation.

Effects of dehydroepiandrosterone therapy on pubic hair growth and psychological well-being in adolescent girls and young women with central adrenal insufficiency: a double-blind, randomized, placebo-controlled phase III trial.

CONTEXT AND OBJECTIVE: The efficacy of oral dehydroepiandrosterone (DHEA) in the treatment of atrichia pubis and psychological distress in young females with central adrenal insufficiency is unknown. Our study aimed to evaluate this therapy. DESIGN AND PATIENTS: A total of 23 young females (mean age 18 yr, range 13-25) was enrolled in a double-blind randomized placebo-controlled trial. Inclusion criteria were ACTH deficiency plus two or more additional pituitary deficiencies, serum DHEA less than 400 ng/ml, and pubertal stage more than B2. Exclusion criteria were cerebral radiation with more than 30 Gy, tumor remission less than 1 yr, amaurosis, hypothalamic obesity, psychiatric disorders, and unstable hormone medication. INTERVENTION: Patients were randomized to placebo (n = 12) or 25 mg HPLC-purified DHEA/d (n = 11) orally for 12 months after stratification into a nontumor (n = 7) and a tumor group (n = 16). MAIN OUTCOME MEASURES: Clinical scoring of pubic hair stage was performed at 0, 6, and 12 months (primary endpoint), and psychometrical evaluation (Symptom Check-List-90-R and the Centre for Epidemiological Studies-Depression Scale) at 0 and 12 months (secondary endpoint). Androgen levels and safety parameters were measured at 0, 6, and 12 months; 24-h androgen urinary excretion rates were calculated at 0 and 12 months. RESULTS: In the placebo group, four patients dropped out because of recurrence of craniopharyngioma, manifestation of type 1 diabetes, and change of residence (n = 2); in the DHEA group, one patient dropped out because of recurrent anxiety attacks. DHEA substitution resulted in normalization of DHEA sulfate and androstanediol glucuronide morning serum levels 2 h after drug intake (P < 0.006), and of its 24 h urinary metabolite levels (P < 0.0001), placebo had no effect. Morning serum levels of androstenedione increased in the DHEA group (P < 0.02) but did not normalize. The DHEA group exhibited significant progress in pubic hair growth from Tanner stage I-III to II-V (mean: +1.5 stages), whereas the placebo group did not (relative risk 0.138; 95% confidence interval 0.021-0.914; P = 0.0046). Importantly, eight of the 10 Symptom Check-List-90-R scores, including those for depression, anxiety, and interpersonal sensitivity, and the global severity index improved in the DHEA group in comparison to the placebo group (P < 0.048). DHEA was well tolerated. CONCLUSIONS: In adolescent girls with central adrenal insufficiency, daily replacement with 25 mg DHEA orally is beneficial: atrichia pubis vanishes, and psychological well-being improves significantly.

Continuous rise in incidence of childhood Type 1 diabetes in Germany.

AIMS: To assess the incidence and the trend in incidence of Type 1 diabetes (T1DM) in children and adolescents < 15 years of age in Baden-Württemberg (BW), Germany. METHODS: BW is Germany's third largest federal state. All 31 paediatric departments in BW and one diabetes centre participated in the study. Case registration was done according to the EURODIAB criteria. The degree of ascertainment was 97.2%. RESULTS: From 1987 to 2003, the age- and sex-standardized incidence rate was 14.1/100,000 per year [95% confidence interval (CI) 13.7, 14.6, n = 4017]. The estimated annual increase in incidence was 3.8% (95% CI 1.1, 6.6). Compared with the first years of our registry, the current mean number of new cases of T1DM has doubled (1987-1989, n = 153; 2000-2003, n = 302). Generally, the highest rise in incidence occurred in the youngest age group of 0-4-year-old patients (5.8%; 95% CI 2.5, 9.3), followed by the age groups 5-9 (3.4%; 95% CI 0.8, 6.0) and 10-14 (2.7%; 95% CI 0.3, 5.1). CONCLUSIONS: In Germany, the number of children and adolescents with new-onset T1DM has been rising at a faster pace than expected. A distinct shift to younger age at onset has been observed in Germany.

Human growth hormone measurement by means of a sensitive ELISA of whole blood spots on filter paper.

BACKGROUND: Measurements of human growth hormone (hGH) are a prerequisite for identifying a deficiency or excess. Our study is the first to investigate the reliability of a very sensitive assay for the quantification of GH in dried blood spots on filter paper. OBJECTIVE: Validation of a commercially-available enzyme-linked immunoassay (ELISA) for measuring hGH from filter paper samples of dried blood. METHODS: We used an assay system (ELISA, E022, Mediagnost) based on polyclonal rabbit antibodies. Its suitability is ascribable to its very high sensitivity (1.6 ng/L) and virtual absence of interfering factors, excepting for a cross-reactivity with high pegvisomant concentrations. RESULTS: hGH was found to be stable in dried blood spots on filter paper (No. 903, Whatman) over eight days at 37 degrees C. Extraction of hGH from filter paper, in comparison to EDTA plasma, was 107% (SD 8.1%; n=6) over a range from 2.4 to 34.5 microg/L. Linear regression analysis (n=119) showed a correlation of R(2)=0.97 for the hGH concentration in serum and on filter paper samples. CONCLUSION: Our findings demonstrate the reliability of measurements of hGH in dried blood spots on filter paper. The advantages of this method are the low sample volume and the easy transport, storage, and handling of samples. This method contributes to the standardisation of diagnostics pertaining to abnormal hGH secretion as it facilitates the comparison of decisive measurements.

Use of multiplex ligation-dependent probe amplification increases the detection rate for 11p15 epigenetic alterations in Silver-Russell syndrome.

Silver-Russell syndrome (SRS) describes a malformation syndrome with severe intrauterine and postnatal growth retardation. Currently, two major (epi)mutations have been described: while approximately 10% of patients carry a maternal uniparental disomy of chromosome 7 (UPD7), 35-60% show a hypomethylation at the H19 differentially methylated regions (DMRs) in 11p15. Until recently, a Southern-blot based test was routinely used to identify epimutation carriers. Nevertheless, this test was time consuming and hampered by the huge amount of genomic DNA needed. With the methylation-specific multiplex ligation-dependent probe amplification assay (MLPA) for SRS, a PCR-based test is now available, allowing the analysis also of small amounts of DNA. Probes in this assay hybridize to the H19 DMRs but do not cover the genomic target of the Southern-blot probe. We now screened 72 patients with SRS by MLPA. Hypomethylation of the H19 DMRs was confirmed in all patients analyzed by Southern blot. In addition, we identified six individuals with hypomethylation of the H19 DMR who had previously normal blot results. This discrepancy can be explained by the observed generally lower degree of demethylation in this group, possibly not detectable by the less sensitive Southern-blot method but also with a varying degree of methylation at different DMRs in the same individual. Apart from hypomethylation in the H19 DMR, we observed a slight demethylation for one of the IGF2 probes. The total detection rate of 11p15 hypomethylation is now increased to >38%. Considering maternal UPD7 and chromosomal aberrations, (epi)genetic alterations now account for more than 50% of SRS patients. In summary, MLPA represents an easy, low cost and reliable system in the molecular diagnostics of SRS.

Mutant and misfolded human growth hormone is rapidly degraded through the proteasomal degradation pathway in a cellular model for isolated growth hormone deficiency type II.

Autosomal dominant isolated growth hormone deficiency type II (IGHD II) is mainly caused by splice site mutations of the GH-1 gene, leading to deletion of amino acids 32-71 of the human growth hormone (hGH). The severe hGH deficit in IGHD II suggests a dominant negative effect of the partially deleted del(32-71)-hGH on the production, storage or secretion of normal wild-type (wt)-hGH in somatotrophic cells of the pituitary. To shed more light on the cellular and molecular basis of IGHD II, we established and analysed diverse clones of the rat somatotrophic cell line GH(4)C(1) stably expressing either wt-hGH, del(32-71)-hGH, or both proteins concomitantly. The cellular morphology of all transfected GH(4)C(1) cell clones showed moderate differences to untransfected GH(4)C(1) cells. On the molecular level, both cDNA-constructs induced transcription but, under normal culture conditions, only wt-hGH protein was found to be synthesised and secreted in readily detectable amounts. By contrast, only after inhibition of proteasomes did high amounts of del(32-71)-hGH show up. The solubility of del(32-71)-hGH in nondenaturing buffer was poor compared to wt-hGH, hinting at molecular aggregation, and several epitopes recognised by monoclonal hGH antibodies were not present on del(32-71)-hGH, confirming the assumption that del(32-71)-hGH must be severely misfolded. Expression of both proteins in Escherichia coli mirrored the findings from the GH(4)C(1) cell clones in terms of solubility and immunological reactivity. The results of the present study indicate that, in IGHD II, somatotrophs continuously have to remove misfolded del(32-71)-hGH via the proteasomal degradation pathway, suggesting a mechanism that may result in chronic cellular stress.