[MIM 146 000]

Incidence: about 1/33,000. Autosomal dominant transmission or de novo mutation of the FGFR3 gene (4p16.3). Very similar to achondroplasia but:

-         less marked short stature: adult height between 125 and 160 cm

-         less marked micromelia and lumbar hyperlordosis

-        no facial dysmorphism, orthopedic malformations or neurological problems

-        the lower limbs may be curved

-        less severe radiological abnormalities

-        intellectual development is most often normal.

The diagnosis is usually evoked after 2 to 4 years of age following slowing of the growth curve.

Experimental treatments: (similar to those for achondroplasia)

-        in phase 3: Vosoritide (CNP (C-type natriuretic peptide) analogue) 15 µg/kg subcutaneously every day.

-        phase 1 or 2:

*        navepegritide: CNP (C-type natriuretic peptide) analog: weekly subcutaneous injection

*        infigratinib: selective FGFR1-3 inhibitor, p os

*        meclizine: antihistamine, os

*        SAR-442501: monoclonal antibody against FGFR3

*        RBM-007: FGFR3 receptor blocker for fibroblasts

These treatments increase bone growth, but their long-term effects and potential drug interactions are still unknown.

Anesthetic implications : 

see achondroplasia

References:

-        Savarirayan R, Hoover-Fong J, Yap P, Fredwall. SO.
New treatments for children with achondroplasia.
Lancet Child Adolesc Health 2024; 8: 301–10

Updated: May 2024