Growth velocity and biological variables during puberty in achondroplasia

Achondroplasia is the most common form of inherited disproportionate short stature. Cross-sectional design studies of height show that, during childhood, height standard deviation scores (SDS) declines steadily and reaches a mean adult height at -6.42 and -6.72 SDS. However, there is a lack of knowledge about longitudinal growth and biological variables during puberty for children with achondroplasia. Here we report the growth velocity and biological parameters during puberty in children with achondroplasia.

The study was an observational, cohort study. A total of 23 patients, 15 girls and eight boys with achondroplasia, who reached adult size were included. Growth data was collected from mid-childhood until final height by the same trained observer. Individual growth curves were estimated by fitting the Preece-Baines model 1 (PB1) to each individual's height for age data. Pubertal development was scored on Tanner scale on each visit.

In boys with achondroplasia the mean adult height was 129.18 cm. Age and velocity at peak velocity in puberty were 13.89 years and 4.86 cm/year, respectively. The adolescent gain was 20.40 cm. Mean age at genital development 2 and 5 were 12.16 (0.60) and 14.97 (0.88), respectively. In girls the mean adult height was 118.67 cm. Age and velocity at peak velocity in puberty were 11.45 years and 4.40 cm/year, respectively. The adolescent gain was 19.35 cm. Mean age at breast 2 and 4 were 10.20 (1.24) and 12.49 (1.07), respectively.

Children with achondroplasia experienced an adolescent growth spurt, which was similar in shape and half the magnitude of the non-achondroplasia population.