Prospective Clinical Assessment Study in Children With Achondroplasia (ACH)

Key Inclusion Criteria:

• Signed informed consent by study participant or parent(s) or legally authorizedrepresentative (LAR) and signed informed assent by the study participant (whenapplicable)

• Aged 2.5 to <17 years at study entry

• Diagnosis of ACH

• Study participants and parent(s) or LAR(s) are willing and able to comply with studyvisits and study procedures

Key Exclusion Criteria:

• Have hypochondroplasia or short stature condition other than ACH (e.g. trisomy 21,pseudoachondroplasia, psychosocial short stature)

• In females, having had their menarche

• Height < -2 or > +2 standard deviations for age and sex based on reference tables ongrowth in children with ACH

• Annualized height growth velocity ≤1.5 cm/year over a period ≥6 months prior toscreening

• Current evidence of corneal or retinal disorder/keratopathy

• Current evidence of endocrine alterations of calcium/phosphorus homeostasis

• Have a concurrent disease or condition that in the view of the Investigator and/orSponsor, may impact growth or where the treatment is known to impact growth.

• Significant abnormality in screening laboratory results.

• Have been treated with growth hormone, insulin-like growth factor 1 (IGF 1), oranabolic steroids in the previous 6 months or long-term treatment (>3 months) at anytime

• Have had regular long-term treatment (>1 month) with oral corticosteroids (low-doseongoing inhaled steroid for asthma is acceptable)

• Have had previous guided growth surgery or limb-lengthening surgery within 12 monthsprior to screening.