Acondroplasia

Overview

  • EPIC Code:
  • LAB1794
  • Soft Test Code:
  • ACDR
  • Send Out Test Code:
  • FGRF3
Alternate Names
  • ACH
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


Specimen Collection & Preparation

Client Notes:

Please contact the laboratory at 266-1500 (Option 1) if prenatal testing and for payment requirements of this test


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


Alternate Specimen

 


TransportAndStorage

 


Collection Instructions

 


Minimum Volume

1.0 mL


Neonatal Volumne

Clinical Interpretation

Reference Range:

Refer to Interpretive Results


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:
  • Polymerase Chain Reaction (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


Production Schedule

Departments
  • Sendouts - Clinical
Turn Around Time

10 days


Coding & Compliance

CPT Coding

83892 x 2, 83894 x 2, 83898 x 3,