What is this test for?

This test detects 2 disease-causing mutations in the FGFR3 gene, which accounts for approximately 99% of achondroplasia cases.

What is achondroplasia?

Achondroplasia is a common form of dwarfism (short stature) caused by gene mutation. Affected individuals have short stature, characteristic facies and exaggerated curvature of the lower back. Hyperextensibility of the knees and other joints are common too. Achondroplasia occurs in approximately 1 in 15,000 live births.

What causes achondroplasia?

Approximately 99% of achondroplasia is caused by 2 point mutations of the FGFR3 gene. The altered receptor is overly active upon fibroblast growth factor binding, thus disturbing normal cell signaling. Individuals who have a single copy of the altered FGFR3 gene will have achondroplasia. The altered FGFR3 gene comes from de novo mutation (i.e. parents with normal stature) in more than 80% of affected individuals. 

What is de novo mutation?

De novo mutation is the alteration of a gene that is present for the first time in one family member as a result of a mutation in the egg or sperm of one of the parents or in the fertilized egg itself. De novo mutations are associated with advanced paternal age (i.e. over 35 years of age).

Who should consider this test?

• High risk pregnancy (one or both parents have achondroplasia)
• Low risk pregnancy (ultrasound examination may identify short fetal limbs and raise the possibility of achondroplasia)
• Paternal age over 35 years
• Family planning
• Confirmatory testing for individuals who suspect of having achondroplasia

測試詳情

Rejection criteria

• Specimen without proper labeling
• Specimen not in requested format or insufficient quantity
• Specimen in container expired for more than 1 month
• Container leakage
• Sampling date is more than 7 days
• Frozen specimen, haemolysed or clotted blood specimen

Factor(s) known to affect results

• Improper collection, handling and storage of specimen