Mutations in NOTCH2 in families with Hajdu-Cheney syndrome.
ABSTRACT Hajdu-Cheney syndrome (HCS) is a rare genetic disorder whose hallmark is acro-osteolysis, shortening of terminal phalanges, and generalized osteoporosis. We assembled a cohort of seven families with the condition and performed whole exome resequencing on a selected set of affected patients. One protein-coding gene, NOTCH2, carried heterozygous truncating variants in all patients and their affected family members. Our results replicate recently published studies of HCS and further support this as the causal gene for the disorder. In total, we identified five novel and one previously reported mutation, all clustered near the carboxyl terminus of the gene, suggesting an allele specific genotype-phenotype effect since other mutations in NOTCH2 have been reported to cause a form of Alagille syndrome. Notch-mediated signaling is known to play a role in bone metabolism. Our results support a potential therapeutic role for Notch pathways in treatment of osteoporosis.
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ABSTRACT: The skeleton originates from stem cells residing in the sclerotome and neural crest that undergo proliferation, migration, and commitment. The development of the skeletal stem cells is influenced by many signaling pathways that govern cell fate determination, proliferation, differentiation, and apoptosis. This review will focus on Notch signaling functions in regulating the different cell types that form the skeletal system as well as the interplay between them to maintain homeostasis. Osteochondroprogenitors require Notch signaling to maintain multipotency and to prevent premature differentiation into osteoblasts. Subsequently, overactivation of Notch signaling suppresses osteoblast maturation. Moreover, Notch signaling in osteochondroprogenitors is required for chondrocyte proliferation and hypertrophy and suppresses terminal differentiation. Translational studies demonstrated a crucial role of Notch signaling in osteosarcoma and osteoarthritis, where concepts derived from developmental pathways are often recapitulated. This brings hope of taking advantage of the molecular mechanisms learned from development to approach the pathological processes underlying abnormal bone/cartilage metabolism or tumorigenesis. Pharmacological agents that target Notch receptors or ligands in a tissue-specific fashion would offer new opportunities for treating bone/cartilage diseases caused by dysregulation of Notch signaling.Calcified Tissue International 08/2013; · 2.50 Impact Factor
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ABSTRACT: A 21-year-old man with diabetic ketoacidosis (DKA) displayed short and clubbed fingers and marked eyebrow, which are typical of Hajdu-Cheney Syndrome (HCS). Laboratory findings confirmed type 1 diabetes mellitus (DM). After conservative care with hydration and insulin supply, metabolic impairment was improved. Examinations of bone and metabolism revealed osteoporosis and craniofacial abnormalities. The mutation (c.6443T>G) of the NOTCH2 gene was found. The patient was diagnosed with HCS and DM. There may be a relationship between HCS and DM, with development of pancreatic symptoms related to the NOTCH2 gene mutation.Journal of Korean medical science 11/2013; 28(11):1682-1686. · 0.84 Impact Factor
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ABSTRACT: Work over the past 25 years has resulted in the identification of genes responsible for ~50% of the estimated 7,000 rare monogenic diseases, and it is predicted that most of the remaining disease-causing genes will be identified by the year 2020, and probably sooner. This marked acceleration is the result of dramatic improvements in DNA-sequencing technologies and the associated analyses. We examine the rapid maturation of rare-disease genetic analysis and successful strategies for gene identification. We highlight the impact of discovering rare-disease-causing genes, from clinical diagnostics to insights gained into biological mechanisms and common diseases. Last, we explore the increasing therapeutic opportunities and challenges that the resulting expansion of the 'atlas' of human genetic pathology will bring.Nature Reviews Genetics 09/2013; · 41.06 Impact Factor