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Klaus Prank, Egbert Schulze, Olaf Eckert, Tim W Nattkemper, Markus Bettendorf, Christiane Maser-Gluth, Terrence J Sejnowski, Arno Grote, Erika Penner, Alexander von zur Mühlen, and Georg Brabant

Objective: Non-linear relations between multiple biochemical parameters are the basis for the diagnosis of many diseases. Traditional linear analytical methods are not reliable predictors. Novel nonlinear techniques are increasingly used to improve the diagnostic accuracy of automated data interpretation. This has been exemplified in particular for the classification and diagnostic prediction of cancers based on expression profiling data. Our objective was to predict the genotype from complex biochemical data by comparing the performance of experienced clinicians to traditional linear analysis, and to novel non-linear analytical methods.

Design and methods: As a model, we used a well-defined set of interconnected data consisting of unstimulated serum levels of steroid intermediates assessed in 54 subjects heterozygous for a mutation of the 21-hydroxylase gene (CYP21B) and in 43 healthy controls.

Results: The genetic alteration was predicted from the pattern of steroid levels with an accuracy of 39% by clinicians and of 64% by linear analysis. In contrast, non-linear analysis, such as self-organizing artificial neural networks, support vector machines, and nearest neighbour classifiers, allowed for higher accuracy up to 83%.

Conclusions: The successful application of these non-linear adaptive methods to capture specific biochemical problems may have generalized implications for biochemical testing in many areas. Nonlinear analytical techniques such as neural networks, support vector machines, and nearest neighbour classifiers may serve as an important adjunct to the decision process of a human investigator not ‘trained’ in a specific complex clinical or laboratory setting and may aid them to classify the problem more directly.

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Berthold P Hauffa, Nils Lehmann, Markus Bettendorf, Otto Mehls, Helmuth-Günther Dörr, Nikolaus Stahnke, Heinz Steinkamp, Elfriede Said, Michael B Ranke, and participating members of the German KIGS Board/Medical Outcome Study Group



Childhood GH deficiency, suspected in the presence of decreased height velocity and short stature, is usually characterized by low IGF-I and IGF-binding protein-3 (IGFBP-3) serum concentrations and is conventionally confirmed by diminished GH peak responses to pharmacological stimuli.


We evaluated the agreement between different IGF-I (IGFBP-3) assays in predicting GH deficiency and tested whether variability between growth factor screening and pharmacological testing could be diminished by reassessment of growth factor and GH peak concentrations in a single laboratory.


Using the Tuebingen IGF-I (IGFBP-3) RIA, 317 (321) sera from children evaluated for growth disorders in 19 centers were reanalyzed. In 103 children with insulin hypoglycemia and arginine tests, we evaluated how the association between the outcome of growth factor screening and functional testing would change if different assays were employed.


Locally measured IGF-I correlated better than IGFBP-3 with the results of the central laboratory (Tuebingen) assay (slope of the regression curve 1.05; 95% confidence interval (95% CI) 1.01–1.1 versus 1.18; 95% CI 1.09–1.3). Agreement between local and central laboratory assays in predicting GH deficiency was better for IGF-I than for IGFBP-3 assays (κ=0.59 versus κ=0.47). The poor agreement between growth factor screening and GH pharmacological testing was not improved when hormone concentrations were remeasured in the central laboratory (κ local=−0.0031, central=0.12).


In children with impaired growth, growth factor screening reflects different aspects of GH insufficiency than does functional testing. Agreement between these approaches is poor and could not be improved by reduction of assay-related variability.

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Angela K Lucas-Herald, Jillian Bryce, Andreas Kyriakou, Marie Lindhardt Ljubicic, Wiebke Arlt, Laura Audí, Antonio Balsamo, Federico Baronio, Silvano Bertelloni, Markus Bettendorf, Antonia Brooke, Hedi L Claahsen-van der Grinten, Justin Davies, Gloria Hermann, Liat de Vries, Ieuan A Hughes, Rieko Tadokoro-Cuccaro, Feyza Darendeliler, Sukran Poyrazoglu, Mona Ellaithi, Olcay Evliyaoglu, Simona Fica, Lavinia Stejereanu, Aneta Gawlik, Evgenia Globa, Nataliya Zelinska, Tulay Guran, Ayla Güven, Sabine Hannema, Olaf Hiort, P-m Holterhus, Violeta Iotova, Vilhelm Mladenov, Vandana Jain, Rajni Sharma, Farida Jennane, Colin Johnston, Gil Guerra-Junior, Daniel Konrad, Odile Gaisl, Nils P Krone, Ruth Krone, Katherine Lachlan, Dejun Li, Corina Lichiardopol, Lidka Lisá, Renata Levoni Markosyan, Inas Mazen, Klaus Mohnike, Marek Niedziela, Anna Nordenstrom, Rodolfo A Rey, Mars Skae, Lloyd JW Tack, Jeremy W Tomlinson, Naomi Weintrob, Martine Cools, and S Faisal Ahmed

Objectives: To determine trends in clinical practice for individuals with DSD requiring gonadectomy.

Design: Retrospective cohort study.

Methods: Information regarding age at gonadectomy according to diagnosis; reported sex; time of presentation to specialist center; and location of center from cases reported to the International DSD Registry and who were over 16 years old in January 2019.

Results: Data regarding gonadectomy were available in 668 (88%) individuals from 44 centers. Of these, 248 (37%) (median age (range) 24 (17, 75) years) were male and 420 (63%) (median age (range) 26 (16, 86) years) were female. Gonadectomy was reported from 36 centers in 351/668 cases (53%). Females were more likely to undergo gonadectomy (n=311, p<0.0001). The indication for gonadectomy was reported in 268 (76%). The most common indication was mitigation of tumour risk in 172 (64%). Variations in the practice of gonadectomy were observed; of the 351 cases from 36 centers, 17 (5%) at 9 centers had undergone gonadectomy before their first presentation to the specialist center. Median age at gonadectomy of cases from high income countries and low/middle income countries (LMIC) was 13.0 yrs (0.1, 68) years and 16.5 yrs (1, 28), respectively (p<0.0001) with the likelihood of long-term retention of gonads being higher in LMIC countries.

Conclusions: The likelihood of gonadectomy depends on the underlying diagnosis, sex of rearing and the geographical setting. Clinical benchmarks, which can be studied across all forms of DSD will allow a better understanding of the variation in the practice of gonadectomy.