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. 2025 Nov 3;20(1):555.
doi: 10.1186/s13023-025-04069-5.

Achondroplasia and hypochondroplasia in France: a nationwide epidemiological analysis

Genevieve Baujat  1 , Marc-Antoine Hamandjian  2 , Anne-Sophie Jannot  3 , Pierre Karam  4 , Valérie Cormier-Daire  5
Affiliations

Achondroplasia and hypochondroplasia in France: a nationwide epidemiological analysis

Genevieve Baujat et al. Orphanet J Rare Dis. .

Abstract

Background: Achondroplasia (ACH) and hypochondroplasia (HCH) are among the most common forms of skeletal dysplasia, caused by gain-of-function variants in the FGFR3 gene, leading to disproportionate short stature. The birth prevalence of HCH remains poorly defined. In addition, the reported birth prevalence of ACH in Europe and globally may not be applicable to France, given its relatively high rate of pregnancy terminations for medical reasons. This retrospective study provides the first birth prevalence estimates for ACH and HCH in France, using the French National Registry of Rare Diseases (Banque Nationale de Données Maladies Rares, BNDMR).

Results: As of January 2024, 766 patients with ACH (ORPHA:15) and 408 with HCH (ORPHA:429) were identified. Most patients were diagnosed and cared for within the network of constitutional bone diseases centers (ACH: 71.3%; HCH: 63.4%). Overall, 85.5% of ACH cases and 57.2% of HCH cases were related to de novo genetic variants (p < 0.0001). ACH was diagnosed prenatally in 40.8% and at birth in 40.6% of patients, whereas HCH was diagnosed postnatally in 65.7% of cases (p < 0.0001). To estimate live birth prevalence, we focused on pediatric patients (0-15 years) born between 2008 and 2023. The mean (range) live birth prevalence was 3.27 per 100,000 for ACH (1.90-4.03) and 1.31 per 100,000 for HCH (0.54-2.08).

Conclusions: This study provides the first nationwide birth prevalence estimates for ACH and HCH in France, leveraging data from BNDMR. ACH is often identified prenatally, whereas HCH is predominantly diagnosed postnatally. The prevalence of HCH may be underestimated due to under-recognition of milder forms. With the emergence of specific therapies for ACH, and for HCH in the near future, strengthening specialized care pathways is critical to ensure equitable access to timely diagnosis and interventions.

Clinical trial number: Not applicable.

Keywords: Achondroplasia; BNDMR; Epidemiology; France; Hypochondroplasia; Prevalence.

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Conflict of interest statement

Declarations. Ethics approval and consent to participate: This non-interventional study was approved by the BNDMR scientific committee (BPD-2018-DIAG-008/-002) and registered with the French Data Protection Authority (CNIL: MR004) and the AP-HP local registry (#20230314171333). In accordance with French law, patients were informed about the inclusion of their data in BNDMR and had the opportunity to object to its use for research. Only those who did not object were included in our study. Consent for publication: All authors agree with the content of the manuscript. All authors have agreed to the submission and publication of this manuscript. Competing interests: GB declares competing interests for advisory consultancy and expert report production for BioMarin, Inozyme, Ipsen, Sanofi, and Alexion; participation in scientific work for Incyte, Ipsen, QED, Ascendis, BioMarin, Alexion, Clementia, and Therachon Pfizer; and writing articles and interventions for Elsevier, BioMarin, Ipsen, and Alexion. MAH is a BioMarin employee and has stock options. ASJ and PK have no conflicts of interest to declare. VCD declares competing interests related to advisory consultancy or interventions for BioMarin and QED.

Figures

Fig. 1
Fig. 1
Description of the achondroplasia (ACH) (a) and hypochondroplasia (HCH) (b) study populations
Fig. 2
Fig. 2
Number of patients with ACH recorded in BNDMR, by year of birth. Abbreviations: ACH, achondroplasia; BNDMR, Banque Nationale de Données Maladies Rares [French National Registry of Rare Diseases]
Fig. 3
Fig. 3
Number of patients with HCH recorded in BNDMR, by year of birth. Abbreviations: BNDMR, Banque Nationale de Données Maladies Rares [French National Registry of Rare Diseases]; HCH, hypochondroplasia
See this image and copyright information in PMC

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