Morten Frost1, Michaela Tencerova2, Christina M Andreasen3, Thomas L Andersen4, Charlotte Ejersted5, Dea Svaneby6, Weimin Qui7, Moustapha Kassem8, Allahdad Zarei9, William H McAlister10, Deborah J Veis11, Michael P Whyte12, Anja L Frederiksen13. 1. Department of Clinical Research, Faculty of Health, University of Southern Denmark (SDU), Winsløwparken 19. 3, DK-5000 Odense C, Denmark; Steno Diabetes Center Odense, Odense University Hospital (OUH), J.B. Winsløws Vej 4, DK-5000 Odense C, Denmark; Department of Endocrinology, Molecular Endocrinology Unit, OUH, J.B. Winsløws Vej 4, DK-5000 Odense C, Denmark. Electronic address: morten.munk.frost.nielsen@rsyd.dk. 2. Department of Endocrinology, Molecular Endocrinology Unit, OUH, J.B. Winsløws Vej 4, DK-5000 Odense C, Denmark. Electronic address: mtencerova@health.sdu.dk. 3. Orthopaedic Research Laboratory, Department of Orthopaedic Surgery & Traumatology, OUH, J.B. Winsløws Vej 15, DK-5000 Odense C, Denmark; Department of Clinical Cell Biology, Vejle Hospital, Beridderbakken 4, DK-7100 Vejle, Denmark. Electronic address: cmandreasen@health.sdu.dk. 4. Department of Clinical Cell Biology, Vejle Hospital, Beridderbakken 4, DK-7100 Vejle, Denmark. Electronic address: Thomas.Levin.Andersen@rsyd.dk. 5. Department of Endocrinology, Molecular Endocrinology Unit, OUH, J.B. Winsløws Vej 4, DK-5000 Odense C, Denmark. Electronic address: Charlotte.Ejersted@rsyd.dk. 6. Department of Clinical Genetics, Vejle Hospital, Beridderbakken 4, DK-7100 Vejle, Denmark. Electronic address: Dea.Svaneby@rsyd.dk. 7. Department of Endocrinology, Molecular Endocrinology Unit, OUH, J.B. Winsløws Vej 4, DK-5000 Odense C, Denmark. 8. Department of Endocrinology, Molecular Endocrinology Unit, OUH, J.B. Winsløws Vej 4, DK-5000 Odense C, Denmark. Electronic address: mkassem@health.sdu.dk. 9. Division of Bone and Mineral Diseases, Department of Internal Medicine, Washington University School of Medicine at Barnes-Jewish Hospital, St. Louis, MO, USA. Electronic address: azarei@wustl.edu. 10. Department of Pediatric Radiology, Mallinckrodt Institute of Radiology, Washington University School of Medicine at St. Louis Children's Hospital, St. Louis, MO, USA. Electronic address: mcalisterw@mir.wustl.edu. 11. Center for Metabolic Bone Disease and Molecular Research, Shriners Hospital for Children, St. Louis, MO, USA; Division of Bone and Mineral Diseases, Department of Internal Medicine, Washington University School of Medicine at Barnes-Jewish Hospital, St. Louis, MO, USA. Electronic address: dveis@wustl.edu. 12. Center for Metabolic Bone Disease and Molecular Research, Shriners Hospital for Children, St. Louis, MO, USA; Division of Bone and Mineral Diseases, Department of Internal Medicine, Washington University School of Medicine at Barnes-Jewish Hospital, St. Louis, MO, USA. Electronic address: mwhyte@shrinenet.org. 13. Department of Clinical Research, Faculty of Health, University of Southern Denmark (SDU), Winsløwparken 19. 3, DK-5000 Odense C, Denmark; Department of Clinical Genetics, Odense University Hospital, J.B. Winsløws Vej 4, DK-5000 Odense C, Denmark. Electronic address: Anja.Frederiksen@rsyd.dk.
Abstract
BACKGROUND: NF-κB essential modulator (NEMO), encoded by IKBKG, is necessary for activation of the ubiquitous transcription factor nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB). Animal studies suggest NEMO is required for NF-κB mediated bone homeostasis, but this has not been thoroughly studied in humans. IKBKG loss-of-function mutation causes incontinentia pigmenti (IP), a rare X-linked disease featuring linear hypopigmentation, alopecia, hypodontia, and immunodeficiency. Single case reports describe osteopetrosis (OPT) in boys carrying hypomorphic IKBKG mutations. METHOD: We studied the bone phenotype in women with IP with evaluation of radiographs of the spine and non-dominant arm and leg; lumbar spine and femoral neck aBMD using DXA; μ-CT and histomorphometry of trans-iliac crest biopsy specimens; bone turnover markers; and cellular phenotype in bone marrow skeletal (stromal) stem cells (BM-MSCs) in a cross-sectional, age-, sex-, and BMI-matched case-control study. X-chromosome inactivation was measured in blood leucocytes and BM-MSCs using a PCR method with methylation of HpaII sites. NF-κB activity was quantitated in BM-MSCs using a luciferase NF-κB reporter assay. RESULTS: Seven Caucasian women with IP (age: 24-67 years and BMI: 20.0-35.2 kg/m2) and IKBKG mutation (del exon 4-10 (n = 4); c.460C>T (n = 3)) were compared to matched controls. The IKBKG mutation carriers had extremely skewed X-inactivation (>90:10%) in blood, but not in BM-MSCs. NF-κB activity was lower in BM-MSCs from IKBKG mutation carriers (n = 5) compared to controls (3094 ± 679 vs. 5422 ± 1038/μg protein, p < 0.01). However, no differences were identified on skeletal radiographics, aBMD, μ-architecture of the iliac crest, or bone turnover markers. The IKBKG mutation carriers had a 1.7-fold greater extent of eroded surfaces relative to osteoid surfaces (p < 0.01), and a 2.0-fold greater proportion of arrested reversal surface relative to active reversal surface (p < 0.01). CONCLUSION: Unlike mutation-positive males, the IKBKG mutation-positive women did not manifest OPT.
BACKGROUND: NF-κB essential modulator (NEMO), encoded by IKBKG, is necessary for activation of the ubiquitous transcription factor nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB). Animal studies suggest NEMO is required for NF-κB mediated bone homeostasis, but this has not been thoroughly studied in humans. IKBKG loss-of-function mutation causes incontinentia pigmenti (IP), a rare X-linked disease featuring linear hypopigmentation, alopecia, hypodontia, and immunodeficiency. Single case reports describe osteopetrosis (OPT) in boys carrying hypomorphic IKBKG mutations. METHOD: We studied the bone phenotype in women with IP with evaluation of radiographs of the spine and non-dominant arm and leg; lumbar spine and femoral neck aBMD using DXA; μ-CT and histomorphometry of trans-iliac crest biopsy specimens; bone turnover markers; and cellular phenotype in bone marrow skeletal (stromal) stem cells (BM-MSCs) in a cross-sectional, age-, sex-, and BMI-matched case-control study. X-chromosome inactivation was measured in blood leucocytes and BM-MSCs using a PCR method with methylation of HpaII sites. NF-κB activity was quantitated in BM-MSCs using a luciferase NF-κB reporter assay. RESULTS: Seven Caucasian women with IP (age: 24-67 years and BMI: 20.0-35.2 kg/m2) and IKBKG mutation (del exon 4-10 (n = 4); c.460C>T (n = 3)) were compared to matched controls. The IKBKG mutation carriers had extremely skewed X-inactivation (>90:10%) in blood, but not in BM-MSCs. NF-κB activity was lower in BM-MSCs from IKBKG mutation carriers (n = 5) compared to controls (3094 ± 679 vs. 5422 ± 1038/μg protein, p < 0.01). However, no differences were identified on skeletal radiographics, aBMD, μ-architecture of the iliac crest, or bone turnover markers. The IKBKG mutation carriers had a 1.7-fold greater extent of eroded surfaces relative to osteoid surfaces (p < 0.01), and a 2.0-fold greater proportion of arrested reversal surface relative to active reversal surface (p < 0.01). CONCLUSION: Unlike mutation-positive males, the IKBKG mutation-positive women did not manifest OPT.
Authors: Matteo M Guerrini; Cristina Sobacchi; Barbara Cassani; Mario Abinun; Sara S Kilic; Alessandra Pangrazio; Daniele Moratto; Evelina Mazzolari; Jill Clayton-Smith; Paul Orchard; Fraser P Coxon; Miep H Helfrich; Julie C Crockett; David Mellis; Ashok Vellodi; Ilhan Tezcan; Luigi D Notarangelo; Michael J Rogers; Paolo Vezzoni; Anna Villa; Annalisa Frattini Journal: Am J Hum Genet Date: 2008-07 Impact factor: 11.025