1. Academic Validation
  2. Human osteoclast-poor osteopetrosis with hypogammaglobulinemia due to TNFRSF11A (RANK) mutations

Human osteoclast-poor osteopetrosis with hypogammaglobulinemia due to TNFRSF11A (RANK) mutations

  • Am J Hum Genet. 2008 Jul;83(1):64-76. doi: 10.1016/j.ajhg.2008.06.015.
Matteo M Guerrini 1 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
Affiliations

Affiliation

  • 1 Istituto di Tecnologie Biomediche, Consiglio Nazionale delle Ricerche, Segrate 20090, Italy.
Abstract

Autosomal-Recessive Osteopetrosis (ARO) comprises a heterogeneous group of bone diseases for which mutations in five genes are known as causative. Most ARO are classified as osteoclast-rich, but recently a subset of osteoclast-poor ARO has been recognized as due to a defect in TNFSF11 (also called RANKL or TRANCE, coding for the RANKL protein), a master gene driving osteoclast differentiation along the RANKL-RANK axis. RANKL and RANK (coded for by the TNFRSF11A gene) also play a role in the immune system, which raises the possibility that defects in this pathway might cause osteopetrosis with immunodeficiency. From a large series of ARO patients we selected a Turkish consanguineous family with two siblings affected by ARO and hypogammaglobulinemia with no defects in known osteopetrosis genes. Sequencing of genes involved in the RANKL downstream pathway identified a homozygous mutation in the TNFRSF11A gene in both siblings. Their monocytes failed to differentiate in vitro into osteoclasts upon exposure to M-CSF and RANKL, in keeping with an osteoclast-intrinsic defect. Immunological analysis showed that their hypogammaglobulinemia was associated with impairment in immunoglobulin-secreting B cells. Investigation of Other patients revealed a defect in both TNFRSF11A alleles in six additional, unrelated families. Our results indicate that TNFRSF11A mutations can cause a clinical condition in which severe ARO is associated with an immunoglobulin-production defect.

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