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Test Code PHOX2B PHOX2B Screening

Clinical System Name

PHOX2B Screening

Synonyms

Congenital central hypoventilation syndrome (CCHS)

Description

Congenital central hypoventilation syndrome (CCHS) is a rare disorder of respiratory and autonomic regulation. It is typically characterized by a classic presentation in newborns and, rarely, a milder later-onset (LO-CCHS) presentation in toddlers, children, and adults. Diagnosis of CCHS is established based on: 1) Clinical findings of alveolar hypoventilation and ANSD in the absence of primary pulmonary, cardiac, or neuromuscular disease, or a causative brain stem lesion that can account for the entire phenotype; and 2) Identification of a disease-causing mutation in PHOX2B. PHOX2B is the only gene in which mutations are known to cause CCHS.

Sample Requirements

Specimen: Whole Blood

Container(s): Lavender Top/EDTA

Preferred Vol: 7 mL

Minimum Vol: 3 mL

Processing Instructions

Reject due to: Hemolyzed blood

Spin: N

Aliquot: N

Temp: 2-8 C

Storage location: Refrigerate in CPA refrigerator Sendouts rack.

 

Off-site collection: Send whole blood refrigerated.

Stability

Specimen Type Temperature Time
Whole blood Room temp 3 d
Whole blood Refrigerated 7 d
Whole blood Frozen N

 

Availability

STAT TAT
N 2 w

 

Performing Laboratory

Rush University Medical Center

Department

Department:  Rush University Medical Center, 1750 W Harrison St, Rm 1501 Jelke, Chicago, IL 60612

Phone Number: (312) 942-6298

 

Reference Range

Interpretive report is provided. Normal alleles contain 20 repeats although non-disease causing deleted variants with 14 and 15 repeats have been seen in the normal population.  CCHS-associated alleles contain 25-33 repeats.

Methodology

Method: PCR analysis of the region in exon 3 of PHOX2b coding for the CCHS-associated polyalanine repeat expansion mutation is conducted using primers flanking this region.  The number of alanine-coding triplet repeats in each PHOX2b allele is quantitated via polyacrylamide gel electrophoresis of the PCR product and compared with known standard alleles.

Analytical Volume:

Limitations:

Special Instructions

Links to:

 

Rush University Medical Center test info and requisition

 

Send Out Instructions

Reference Test Name: Congenital Central Hypoventilation Syndrome (CCHS)
Reference Test Number: CCHS DNA
Instructions: Ship whole blood ambient via FedEx to Rush University.