Browsing by Author "Mumm, Steven"

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    Juvenile Paget’s Disease From Heterozygous Mutation of SP7 Encoding Osterix (Specificity Protein 7, Transcription Factor Sp7)
    (Elsevier, 2020-08) Whyte, Michael P.; Campeau, Philippe M.; McAlister, William H.; Roodman, G. David; Kurihara, Nori; Nenninger, Angela; Duan, Shenghui; Gottesman, Gary S.; Bijanki, Vinieth N.; Sedighi, Homer; Veis, Deborah J.; Mumm, Steven; Medicine, School of Medicine
    Juvenile Paget's disease (JPD) became in 1974 the commonly used name for ultra-rare heritable occurrences of rapid bone remodeling throughout of the skeleton that present in infancy or early childhood as fractures and deformity hallmarked biochemically by marked elevation of serum alkaline phosphatase (ALP) activity (hyperphosphatasemia). Untreated, JPD can kill during childhood or young adult life. In 2002, we reported that homozygous deletion of the gene called tumor necrosis factor receptor superfamily, member 11B (TNFRSF11B) encoding osteoprotegerin (OPG) explained JPD in Navajos. Soon after, other bi-allelic loss-of-function TNFRSF11B defects were identified in JPD worldwide. OPG inhibits osteoclastogenesis and osteoclast activity by decoying receptor activator of nuclear factor κ-B (RANK) ligand (RANKL) away from its receptor RANK. Then, in 2014, we reported JPD in a Bolivian girl caused by a heterozygous activating duplication within TNFRSF11A encoding RANK. Herein, we identify mutation of a third gene underlying JPD. An infant girl began atraumatic fracturing of her lower extremity long-bones. Skull deformity and mild hearing loss followed. Our single investigation of the patient, when she was 15 years-of-age, showed generalized osteosclerosis and hyperostosis. DXA revealed a Z-score of +5.1 at her lumbar spine and T-score of +3.3 at her non-dominant wrist. Biochemical studies were consistent with positive mineral balance and several markers of bone turnover were elevated and included striking hyperphosphatasemia. Iliac crest histopathology was consistent with rapid skeletal remodeling. Measles virus transcripts, common in classic Paget's disease of bone, were not detected in circulating mononuclear cells. Then, reportedly, she responded to several months of alendronate therapy with less skeletal pain and correction of hyperphosphatasemia but had been lost to our follow-up. After we detected no defect in TNFRSF11A or B, trio exome sequencing revealed a de novo heterozygous missense mutation (c.926C>G; p.S309W) within SP7 encoding the osteoblast transcription factor osterix (specificity protein 7, transcription factor SP7). Thus, mutation of SP7 represents a third genetic cause of JPD.
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    X-Linked Hypophosphatemia Caused by the Prevailing North American PHEX Variant c.*231A>G; Exon 13-15 Duplication Is Often Misdiagnosed as Ankylosing Spondylitis and Manifests in Both Men and Women
    (Wiley, 2022-11-02) McCrystal Dahir, Kathryn; Black, Margo; Gottesman, Gary S.; Imel, Erik A.; Mumm, Steven; Nichols, Cindy M.; Whyte, Michael P.; Medicine, School of Medicine
    Inactivating mutations of the gene coding for phosphate‐regulating endopeptidase homolog X‐linked (PHEX) cause X‐linked hypophosphatemia (XLH). A novel PHEX variant, c.*231A>G; exon 13–15 duplication, has emerged as a common cause of XLH in North America, emphasizing the importance of delineating its clinical presentation. Here, a comprehensive description of a five‐generation American kindred of 22 treatment‐naïve individuals harboring the c.*231A>G; exon 13–15 duplication is provided. After XLH was diagnosed in the proposita, pro‐active family members used social media to facilitate a timely assessment of their medical history. Most had normal height and 50% were normophosphatemic. Thirteen had been given a diagnosis other than XLH, most commonly ankylosing spondylitis, and XLH was only established after genetic testing. The prevalent phenotypic characteristics of c.*231A>G; exon 13–15 duplication were disorders of dentition (68.2%), enthesopathies (54.5%), fractures/bone and joint conditions (50%), lower‐limb deformities (40.9%), hearing loss/tinnitus (40.9%), gait abnormalities (22.7%), kidney stones/nephrocalcinosis (18.2%), chest wall disorders (9.1%), and Chiari/skull malformation (4.5%). More affected males than females, respectively, had gait abnormalities (42.9% versus 13.3%), lower‐limb deformities (71.4% versus 26.7%), and enthesopathies (85.7% versus 40%). Single phenotypes, observed exclusively in females, occurred in 22.7% and multiple phenotypes in 77.3% of the cohort. However, as many as six characteristics could develop in either affected males or females. Our findings will improve diagnostic and monitoring protocols for XLH.
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    X-Linked Hypophosphatemia Caused by the Prevailing North American PHEX Variant c.*231A>G; Exon 13-15 Duplication Is Often Misdiagnosed as Ankylosing Spondylitis and Manifests in Both Men and Women
    (JBMR, 2022-12-01) McCrystal Dahir, Kathryn; Black, Margo; Gottesman, Gary S.; Imel, Erik A.; Mumm, Steven; Nichols, Cindy M.; Whyte, Michael P.; Medicine, School of Medicine
    Inactivating mutations of the gene coding for phosphate‐regulating endopeptidase homolog X‐linked (PHEX) cause X‐linked hypophosphatemia (XLH). A novel PHEX variant, c.*231A>G; exon 13–15 duplication, has emerged as a common cause of XLH in North America, emphasizing the importance of delineating its clinical presentation. Here, a comprehensive description of a five‐generation American kindred of 22 treatment‐naïve individuals harboring the c.*231A>G; exon 13–15 duplication is provided. After XLH was diagnosed in the proposita, pro‐active family members used social media to facilitate a timely assessment of their medical history. Most had normal height and 50% were normophosphatemic. Thirteen had been given a diagnosis other than XLH, most commonly ankylosing spondylitis, and XLH was only established after genetic testing. The prevalent phenotypic characteristics of c.*231A>G; exon 13–15 duplication were disorders of dentition (68.2%), enthesopathies (54.5%), fractures/bone and joint conditions (50%), lower‐limb deformities (40.9%), hearing loss/tinnitus (40.9%), gait abnormalities (22.7%), kidney stones/nephrocalcinosis (18.2%), chest wall disorders (9.1%), and Chiari/skull malformation (4.5%). More affected males than females, respectively, had gait abnormalities (42.9% versus 13.3%), lower‐limb deformities (71.4% versus 26.7%), and enthesopathies (85.7% versus 40%). Single phenotypes, observed exclusively in females, occurred in 22.7% and multiple phenotypes in 77.3% of the cohort. However, as many as six characteristics could develop in either affected males or females. Our findings will improve diagnostic and monitoring protocols for XLH. © 2022 The Authors. JBMR Plus published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research.