title: Peer group normalization and urine to blood context in steroid metabolomics: the case of CAH and obesity.
abstract: Traditional interpretation of GC-MS output involved the semi-quantitative estimation of outstanding low or high specific metabolites and the ratio between metabolites. Here, we utilize a systems biology approach to steroid metabolomics of a complex steroid-related disorder, using an all-inclusive analysis of the steroidal pathway in the form of a subject steroidal fingerprint and disease signature, providing novel methods of normalization and visualization. The study compares 324 normal children to pure enzymatic deficiency in 27 untreated 21-hydroxylase CAH patients and to complex disease in 70 children with obesity. Steroid profiles were created by quantitative data generated by GC-MS analyses. A novel peer-group normalization method defined each individual subject's control group in a multi-dimensional space of metadata parameters. Classical steroid pathway visualization was enhanced by adding urinary end-product sub-nodes and by color coding of semi-quantitative metabolic concentrations and enzymatic activities. Unbiased automated data analysis confirmed the common knowledge for CAH - the inferred 17-hydroxyprogesterone was up-regulated and the inferred 21-hydroxylase enzyme activity was down-regulated. In childhood obesity, we observe a general decrease of both glucocorticoid and mineralocorticoid metabolites, increased androgens, up-regulation of 17,20-lyase, 17-OHase and 11β-HSD1 activity and down-regulation of 21-OHase enzymatic activity. Our study proved novel normalization and visualization techniques are to be useful in identifying subject fingerprint and disease signature in enzymatic deficiency and insufficiency, while demonstrating hypothesis generation in a complex disease such as childhood obesity.
authors.affiliation: Faculty of Computer Science, Technion - Israel Institute of Technology, Haifa, Israel. Electronic address: edwardv@cs.technion.ac.il.
authors.forename: Edward
authors.initials: E
authors.lastname: Vitkin
authors.affiliation: Agilent Laboratories, Tel Aviv, Israel.
authors.forename: Amir
authors.initials: A
authors.lastname: Ben-Dor
authors.affiliation: The Lokey Interdisciplinary Center for Life Sciences and Engineering, Technion - Israel Institute of Technology, Haifa, Israel.
authors.forename: Michael
authors.initials: M
authors.lastname: Shmoish
authors.affiliation: Steroid Research and Mass Spectrometry Unit, Division of Pediatric Endocrinology & Diabetology, Center of Child and Adolescent Medicine, Justus Liebig University of Giessen, Germany.
authors.forename: Michaela F
authors.initials: MF
authors.lastname: Hartmann
authors.affiliation: Faculty of Computer Science, Technion - Israel Institute of Technology, Haifa, Israel; Agilent Laboratories, Tel Aviv, Israel.
authors.forename: Zohar
authors.initials: Z
authors.lastname: Yakhini
authors.affiliation: Steroid Research and Mass Spectrometry Unit, Division of Pediatric Endocrinology & Diabetology, Center of Child and Adolescent Medicine, Justus Liebig University of Giessen, Germany.
authors.forename: Stefan A
authors.initials: SA
authors.lastname: Wudy
authors.affiliation: The Rappaport Family Faculty of Medicine, Technion - Israel Institute of Technology, Haifa, Israel.
authors.forename: Ze'ev
authors.initials: Z
authors.lastname: Hochberg
mesh_terms: D000293:Adolescent; D000312:Adrenal Hyperplasia, Congenital / Q000097:blood* / Q000652:urine*; D002648:Child; D002675:Child, Preschool; D005260:Female; D006801:Humans; D008297:Male; D055432:Metabolomics / Q000592:standards*; D009765:Obesity / Q000097:blood* / Q000652:urine*; D012016:Reference Values; D013256:Steroids / Q000097:blood* / Q000652:urine*
chemical_list: D013256:Steroids
keywords: Congenital adrenal hyperplasia; Data normalization; Data visualization; Gas chromatography–mass spectroscopy; Obesity; Steroid metabolomics