Bone Mineral Density, Pubertal Status and Ability to Walk are Associated to Fracture Incidence in Patients with Rett Syndrome

Anya Rothenbuhler; Najiba Lahlou; Thierry Bienvenu; Nadia Bahi Buisson; Agnes Linglart

P1-P106

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ESPE Abstracts (2016) 86 P-P1-106

Bone Mineral Density, Pubertal Status and Ability to Walk are Associated to Fracture Incidence in Patients with Rett Syndrome

Anya Rothenbuhler^a, Najiba Lahlou^b, Thierry Bienvenu^c, Nadia Bahi Buisson^d & Agnes Linglart^a

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^aDepartment of Pediatric Endocrinology and Diabetes, Centre de Reference des Maladies Rares du Metabolisme du Calcium et du Phosphore, Bicetre Hospital, Paris Sud University, Le Kremlin Bicetre, France; ^bInsitute for Endocrine and Metabolic Research, Hospital Cochin, Paris-Descartes University, Paris, France; ^cInserm U1016, Institut Cochin, Université Paris-Descartes, Paris, France; ^dPediatric Neurology, Necker Enfants Malades University Hospital, Paris, France.

Background: Rett (RTT) syndrome is a neurodevelopmental disorder related to mutations in the MECP2 gene that affects girls almost exclusively. In Rett syndrome patients have a high incidence of fractures that can occur at a young age.

Objective and hypotheses: One of the objectives of this study was to identify clinical, radiographic and biological parameters associated to fracture incidence.

Method: 89 RTT patients bearing a MECP2 mutation who had no past history of bisphosphonate treatment or orthopedic surgery to the spine were recruited prospectively. The following clinical, radiographic and biological parameters were evaluated: history of fractures and anti-epileptic drugs, ability to walk, BMI, pubertal status, Kerr severity score, daily calorie, calcium and vitamin D intake, bone mineral density (BMD) at the spine and hip using DEXA, X-rays of the spine and urinary calcium excretion.

Results: Mean age of patients was 11.8±7.1 years. 19/89 (21%) of patients had a history of fracture(s). Ambulatory patients had a higher incidence of fractures (41%) compared to those unable to walk (14%) even though they had a higher BMD of −1.72±0.18 Z score SDS at the spine and −2.48±0.23 Z score SDS at hip compared to −3±0.23 and −2.48±0.23, respectively, in non-walking RTT patients. Even though pubertal patients had a higher BMD compared to non-pubertal patients, −1.6±0.33 vs −2.27±0.15 Z score SDS at the spine, the incidence of fractures was the highest (30%) in the pubertal ambulatory patients. BMD at the spine and the hip was significantly lower in patients who had fractures, respectively at −2.78±0.3 and −3.21±0.36 SDS Z-score compared to patients with no history of fractures, respectively at −1.76±0.16 and −2.24±0.18 SDS Z-score. No difference was found for the other studied parameters between the fractured and non-fractured patients. BMD was significantly correlated to the disease severity Kerr score and BMI Z-score.

Conclusion: Pubertal ambulatory RTT patients have the highest incidence of fractures. BMD, ambulatory status and pubertal development are related to fracture incidence in RTT patients.