Efficacy and Safety Evaluation of Recombinant Human Growth Hormone (r-hGH), Saizen®, on a Population of Children With Hypochondroplasia, Treated at Least 3 Years or Until Near Final Height, When Applicable, in Comparison With a Historic Cohort of Non-treated Children

Inclusion Criteria: * Male or female children with hypochondroplasia defined by a disproportional short limb height and a X-ray evidence of shortening of the long bones and failure of increase in the interpedicular distance between lumbar vertebrae L1 and L5 * Result of genetic analysis for mutation of gene FGFR3 already known or ongoing analysis at the beginning of the study * Chronological age greater than or equal to 3 years * Height for chronological age less than or equal to - 2 SDS * Bone age less than or equal to 11 years for girls and 13 years for boys * A written informed consent at the beginning of the pre-treatment period must be obtained from the parent(s)/legal guardian(s). Children able to understand the trial should personally sign and date the written informed consent Additional inclusion criteria for each study prolongation: * Bone age at Month 36 or Month 60 is compatible with treatment prolongation according to investigator opinion * Subject is still under r-hGH treatment with Saizen® at Month 36 or Month 60 * Height gain greater than or equal to + 1 SDS after the 2 first years of treatment for treatment prolongation at Month 36 and growth velocity greater than or equal to 5 centimeter (cm) per year, with bone age less than 14 years for females or less than 16 years for males for treatment prolongation at Month 60 * According to investigator opinion, gene mutations of the subjects are not in connection with observed side effects during the 3 or 5 first y…