For parents of average stature, achondroplasia is sometimes detected by the presence of short limbs on routine prenatal ultrasound performed after 22 weeks. In this situation, the diagnosis can then be confirmed by molecular genetic testing techniques using fetal DNA obtained through amniocentesis. Cesarean section is recommended to deliver babies with achondroplasia, due to their large head size and risk of compression of the brain during the course of a vaginal delivery.
For parents who have achondroplasia or average statured parents with a previously born child with achondroplasia, amniocentesis or chorionic villus sampling (CVS) can be performed. Using cells obtained by these techniques, DNA testing can then be performed and used to identify homozygous/ heterozygous achondroplasia in the pregnancy.
Most neonates with achondroplasia have average lengths and weights at birth. It is our belief that as many as 15% of child with achondroplasia are not recognized at birth.
In the neonate, infant, older child or adult, the diagnosis of achondroplasia can be made by an experienced physician (usually a clinical geneticist) on the basis of physical and radiologic examinations.
Sequencing of the FGFR-3 gene can be done in all patients, but is only required in unusual cases or cases of doubt.