Bone Abstracts (2015) 4 P83 | DOI: 10.1530/boneabs.4.P83

RANKL, OPG, Dkk1 in Duchenne muscular dystrophy

Francesca Broggi1, Silvia Vai1, Lucia Morandi2, Ksenija Gorni3, Grazia D’Angelo 4, Marika Pane5 & Maria Luisa Bianchi1

1Experimental Laboratory for Children’s Bone Metabolism Research, Bone Metabolism Unit, Istituto Auxologico Italiano IRCCS, Milano, Italy; 2Unità Operativa Malattie Neuromuscolari, Istituto Nazionale Neurologico C. Besta IRCCS, Milano, Italy; 3Centro Clinico Nemo, Ospedale Niguarda, Milano, Italy; 4Istituto Medea IRCCS, La Nostra Famiglia, Bosisio Parini (LC), Italy; 5Dipartimento Neurologia Pediatrica, Policlinico Universitario ‘Agostino Gemelli’ Università Cattolica, Roma, Italy.

Low bone mineral density (BMD) and an increased rate of both peripheral and vertebral fractures have been observed in patients with Duchenne muscular dystrophy (DMD). However, studies specifically addressing bone metabolism, BMD and fractures in this disease are still very few.

Our ongoing multicenter, prospective study is aimed to identify the characteristics of the DMD boys with a higher risk of bone loss and fractures, through the evaluation of bone turnover, BMD, and genetic configuration.

We studied a group of 37 DMD boys (mean age 10.6±3.2 years), and are now presenting our preliminary findings, at baseline, on BMD (measured by dual-energy x-ray absorptiometry), serum osteoprotegerin (OPG), receptor activator of nuclear factor kappa-B ligand (RANKL) and Dickkopf-1 (Dkk1) (evaluated for the first time in DMD boys).

In these patients, at baseline, the RANKL/OPG ratio was significantly higher than normal, while Dkk1 was lower (see Table 1). 28 patients (75.7%) had a significantly reduced spine bone mineral apparent density (BMAD) (z-score ≤−2).

A significant correlation was observed between Dkk1 levels and BMAD z-scores (P<0.005) and also between RANKL/OPG ratios and BMAD z-scores (P=0.03).

The imbalance between RANKL and OPG, and the insufficient compensation provided by the reduction of Dkk1, may suggest a possible explanation of the low BMD and increased fragility and fracture risk in boys affected by DMD. Further studies are needed to confirm this hypothesis.

Disclosure: The authors declared no competing interests.

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