ACHONDROPLASIA (ACH)

DNA ANALYSIS

Achondroplasia (ACH) is the most common form of short-limbed dwarfism, is inherited as an autosomal dominant disorder. However, 80 to 90% of cases are sporadic. Two mutations in the fibroblast growth factor receptor 3 (FGFR3) gene on chromosome 4p16.3 have been identified in greater than 99% of ACH patients. Both mutations involve substitution of an arginine for a glycine at amino acid position 380 in the protein. The major mutation accounting for approximately 97% of cases is a G to A transition at nucleotide position 1138. The minor mutation accounting for approximately 2.5% of cases is a G to C transversion at the same position.

Reasons For Referral:

Confirmation of clinical or radiological diagnosis.
Clarification of equivocal diagnosis.

Testing Methodology:

Direct DNA analysis is performed on two mutations in the FGFR3 gene using a n automated high-throughput system that incorporates DNA amplification (PCR), primer extension, and allele resolution by Matrix Assisted Laser Desorption Ionization-Time of Flight (MALDI-TOF) Mass Spectrometry . Mutations tested are: 1138 G-A & 1138 G-C.

Specimen Requirements:

Blood: EDTA (purple-top) tubes: Adults: 14 cc; Child: 6 cc; Infant: 2-3 cc
Requisition form must accompany specimen. Prior to any genetic testing, we recommend genetic counseling and request that the subject, or their legal guardian, sign our consent form and submit it with the sample.

Turnaround Time:

3 weeks

CPT Codes and Prices:

83788, 83914x3, 83912, 83900, 83901, 83891

Shipping Information

Forms:

>> DNA Requisition

Test Codes:

6000