Neuromuscular Characterisation in Late Adolescent and Adult Cystinosis Patients

This is a monocentric study. The enrollment will be performed as routine care in the department of neurology - neuromuscular center of Raymond Poincaré hospital (APHP).

Patients with cystinosis will be consecutively invited to participate in the study until 20 patients are included. This will avoid selection bias if any. For eligible non included patients, a specific non-identifying registry will be set-up with a very restricted number of variables indicative of disease severity at baseline, allowing for a comparison of included and non-included patients.

Participating cystinosis patients will be proposed to attend a one-day hospitalization. Evaluations will be performed during stable state upon baseline and during a follow-up visit 12 months later.

The study expected duration is 30 months with 18 months for patients' inclusion and 12 month-follow-up.

Primary outcomes

• Change in motor function [12 months]: By the Motor Function Measure (MFM) quantitative scale to measure the functional capacities of motors (0-100%, higher scores mean better capacities).

Secondary outcomes

• Change in motor strength [12 months]: By Manual Muscle Testing (MMT). Higher scores mean better outcome.
• Change in walking capacity [12 months]: by the 6-minutes walking test. Higher scores mean better outcome.
• Change in the time to stand test [12 months]: by the time to stand test. Higher scores mean better outcome.
• Change in the the Box and block test [12 months]: by the Box and block test. Higher scores mean better outcome.
• Change in the Nine hole peg test [12 months]: by the Nine hole peg test. Higher scores mean better outcome.
• Change in Perdue pegboard test [12 months]: by Perdue pegboard test. Higher scores mean better outcome.
• Change in Kapanji test [12 months]: by Kapanji test. Higher scores mean better outcome.
• Change in pinch strength [12 months]: by myopinch test. Higher value mean better outcome.
• Change in grip strength [12 months]: by myogrip test. Higher value mean better outcome.
• Change in vital capacity [12 months]: By spirometry. Higher value mean better outcome.
• Change in inspiratory muscles function [12 months]: By inspiratory maximal pressure. Higher value mean better outcome.
• Change in expiratory muscles function [12 months]: By expiratory maximal pressure. Higher value mean better outcome.
• Change in diaphragmatic performance [12 months]: By transdiaphragmatic pressures measurements. Higher value mean better outcome.
• Incidence of breathing disorders during sleep [12 months]: Detection by a polysomnography associated to capnography.
• Change in ratio of fat mass/lean mass [12 months]: By osteodensitometry
• Change in swallowing function - Sidney Swallow questionnaire [12 months]: By the Sidney Swallow questionnaire. Higher scores mean better outcome.
• Change in swallowing function - Salassa and McHorney scores [12 months]: By the Salassa and McHorney scores. Higher scores mean better outcome.
• Change in swallowing function - time of swallowing [12 months]: By the time of swallowing 80 ml of water (normal = 3-4 sec). Higher values mean worse outcome.

Sex: All, ages: 16 Years to any

Inclusion Criteria:

* Patients aged ≥ 16 years;
* Genetically confirmed diagnosis of cystinosis;
* Presenting motor deficiency of at least one muscle;
* Covered by health insurance.

Exclusion Criteria:

* Patient refusal;
* Foreign patients under AME health schema;
* Patients under legal protection;
* Pregnancy or breast-feeding.

• Pascal Laforêt, MD, PhD, Principal investigator, Neurology Department, Raymond Poincaré Hospital, APHP
• Hélène Prigent, MD, PhD, Study director, Physiology department, Raymond Poincaré Hospital, APHP
• Aude Servais, MD, PhD, Study chair, Department of Nephrology and Transplantation, Necker-Enfants Malades University Hospital, APHP