A Clinical Trial to Evaluate Efficacy and Safety of TransCon CNP Compared With Placebo in Infants (0 to <2 Years of Age) With Achondroplasia

Inclusion Criteria: * Written, signed informed consent by the parent(s)/caregiver(s) of the participant, and as required by the institutional review board/human research ethics committee/independent ethics committee (IRB/HREC/IEC). * Male or female younger than 2 years of age at the time of randomization; or for open label sentinel participants, at the time of first administration of IMP. * Clinical diagnosis of achondroplasia (ACH) with genetic confirmation of heterozygous genotype present during screening. * Parent(s)/caregiver(s) willing to follow the protocol and instructions provided, including being able to administer weekly subcutaneous injections of trial treatment. * Compliance to daily Vitamin D supplementation for infants aged 14 days to 1 year. All participants older than 1 year of age with serum 25-hydroxyvitamin D (25OHD) measured below lower limit of reference range at screening should start daily Vitamin D supplementation prior to randomization. * Considered eligible based on the medical history, physical examination, and the results of vital signs, ECG, imaging, and clinical laboratory tests performed during the screening period. Exclusion Criteria: * Known or suspected hypersensitivity to the investigational product or related products (trehalose, tris\[hydroxymethyl\]aminomethane, succinate, and polyethylene glycol \[PEG\]). * Genetic confirmation of ACH homozygous genotype. * Premature birth with gestational age \< 32 weeks. * Premature birth with gesta…