Clinical trial NCT03596554: X-linked Hypophosphatemia and FGF21
Official title: X-linked Hypophosphatemia and Carbohydrate and Lipid Metabolism: a Role for FGF21?
Study type: OBSERVATIONAL
Overall status: COMPLETED
Conditions: X-linked Hypophosphatemia
Lead sponsor: Hospices Civils de Lyon
Sponsor class: OTHER
First posted: 2018-07-24
Enrollment: 39
Sex: ALL
Minimum age (years): 10
Maximum age (years): 18
Standard ages: CHILD
ADULT
Observational model: COHORT
Time perspective: CROSS_SECTIONAL
Sampling method: NON_PROBABILITY_SAMPLE
Study population: Patients aged 10 to 18 years followed in the different sites of the French Reference Center for Rare Diseases of Calcium and Phosphate, and monitored for hypophosphatemic rickets; estimated number to be included, N=40

Brief summary: Fibroblast Growth Factor 23 and Fibroblast Growth Factor 21 are two endocrine Fibroblast Growth Factors, requiring Klotho as a co-factor to promote their systemic actions. Fibroblast Growth Factor 21 is involved in the regulation of glucid and lipid metabolism. Fibroblast Growth Factor 21 Knock Out mice display obesity and hyperglycemia.

In investigators experience, patients with X-linked hypophosphatemia often present with early-onset over-weight that could be partly explained by decreased physical activity because of bone pains and deformations after puberty; however, patients usually display progressive over-weight earlier in life, when there is no limitation of physical activity yet.

To the knowledge of investigators the association between Fibroblast Growth Factor 23, Fibroblast Growth Factor 21 and Klotho in patients with X-linked hypophosphatemia has never been evaluated. Thus, the main objective of this study is to evaluate the glucid and lipid metabolism in patients with X-linked hypophosphatemia, the main working hypothesis being that the genetic deregulation in the Fibroblast Growth Factor 23 axis in patients with X-linked hypophosphatemia induces modifications of Klotho levels (namely decreased levels) that in turn will deregulate the Fibroblast Growth Factor 21 axis (resistance to Fibroblast Growth Factor 21 because of decreased Klotho levels).


Eligibility criteria: Inclusion Criteria:

* Child with X-linked hypophosphatemia with PHEX gene mutation
* Child between 10 and 18 years old
* Child over 10 kg having a blood sample as part of the treatment (due to regulatory constraints for blood volume taken in 30-day period of 40 mL in children over 10 kg)
* Child and parent / holder of parental authority who has been informed of the study and does not object to participate.

Exclusion Criteria:

- Pregnancy in progress

Primary outcomes:
measure: Circulating FGF21
timeFrame: 1 day
Secondary outcomes:
Other outcomes:
Locations:
city: Bron
country: France
facility: Centre de Référence des Maladies Rénales Rares - Centre de Référence des Maladies Rares du Calcium et du Phosphate - Service de Néphrologie, Rhumatologie et Dermatologie Pédiatriques - Hôpital Femme Mère Enfant
city: Paris
country: France
facility: Centre de Référence des Maladies Rares du Calcium et du Phosphore, Service d'Endocrinologie Pédiatrique - Hôpital du Kremlin Bicêtre
city: Toulouse
country: France
facility: Endocrinologie, Maladies Osseuses, Gynécologie, Génétique, Hôpital des Enfants, CHU de Toulouse
Study officials:
References: