Evaluate the Efficacy and Safety of KK8398 in Patients With Achondroplasia（AOBA Study）

Inclusion Criteria:

1. Patients who are between 2.5 and 17.5 years old of age at the time of provisionalregistration. Patients who meet certain criteria in terms of Tanner stage and boneage.

2. Patients who have been diagnosed with achondroplasia through genetic testing.

Exclusion Criteria:

1. Patients who meet the criteria for a certain height determined by age and gender inthe "Growth Chart for Patients with Achondroplasia" at the time of thepre-registration examination

2. Patients who have received treatment with r-hGH or a CNP analogue within a certainperiod prior to the pre-enrollment examination.

3. Patients who have had previous osteotomy or who are scheduled to undergo osteotomyor epiphyseal growth inhibition during the study period. Epiphyseal growthinhibition in which the plate was removed more than 26 weeks prior to thepre-registration examination will not be excluded if the patient has completelyhealed without sequelae, based on the judgment of the investigator orsub-investigator.