Skeletal development of achondroplasia: Analysis of genotyped patients

Background: Achondroplasia is a skeletal dysplasia caused by substitution of arginine for glycine at codon 380 (G380R) mutation of the fibroblast growth factor receptor 3. To date, the developmental course of the phenotype (short stature and skeletal characteristics) has not been clarified in the genotyped population. Methods: The relationship between age and clinical data (height, arm span and measurements of skeletal radiographs) were statistically analyzed from 27 achondroplasia patients with the G380R genotype. Results: The height standard deviation score had positive correlation and decreased with age, while span-to-height ratio did not. Among measurements of skeletal radiographs, the pelvic index, which represents the squared pelvis deformity, were correlated and increased with age. However, interpedicular distance of the first and fourth lumbar vertebrae (L1:L4) ratio as an index for the caudally narrowed pattern of the lumbar spinal canal and fibula-to-tibia ratio for the disproportionally long fibulae were not correlated and did not increase with age. Conclusion: In making a clinical diagnosis of achondroplasia in early infancy, it should be noted that short stature and squared pelvis deformity are not prominent.