Acondroplasia

Last Modified: 2/4/2019 1:47:52 PM


Medical Necessity Documentation:  
Client Notes: Please contact the laboratory at 266-1500 (Option 1) if prenatal testing and for payment requirements of this test

Patient Preparation:  
Specimen Requirements:

3.0 mL Whole Blood in a Lavender Top Tube - EDTA 

Pediatric requirements: 1.0 to 2.0 mL Whole Blood in a Lavender Top Tube - EDTA

Collection Instructions:  
Minimum Volume: 1.0 mL
Transport & Storage: Temperature/Stability:  
Reference Range: Refer to Interpretive Results
Critical Ranges:  
Test Comments: PCR amplification of the region including the G380R mutation, followed by mutation specific restriction enzyme digestion; 99% detection of the G380R mutation
Methodology: PCR Amplification
Clinical Significance: Achondroplasia (ACH) is the most common form of dwarfism (1 in 15,000 births). The classic features include rhizomelic dwarfism, macrocephaly, exaggerated lumbar lordosis and other skeletal abnormalities. Mortality is somewhat increased in childhood and after 40. Intelligence is unaffected. 

More than 80% of ACH cases are spontaneous and 20% are inherited in an autosomal dominant manner. In the inherited form, the disease is considered fully penetrant, and on average, 50% of all children of the affected parent will have the disease. 

Defects in the fibroblast growth factor receptor 3 (FGFR3) gene, have been discovered to cause ACH of both spontaneous and hereditary types. A mutation at nucleotide 1138 which substitutes an arginine for glycine at position 380 (G380R) of FGFR3 occurs in more than 95% of the cases. 

REASONS FOR REFERRAL:To confirm the nature of the dwarfism in an affected individual. To evaluate fetuses with unusually small stature by ultrasound for the possibility of spontaneous ACH. Individuals at risk who wish prenatal diagnosis. For ambiguous patients this test is often included with testing for Hypochondroplasia
Documentation:  
Custom Panel: No

PRODUCTION SCHEDULE

Turn Around Time: 10 days
Other Testing Facility: Saint Francis
PHL Test Code: ACDR
EPIC Test Code: LAB1794
Send Out Test Code: FGRF3
Alternate Test Names: ACH
Included Tests:  
CPT Coding: 83892 x 2, 83894 x 2, 83898 x 3,

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