Alpha Thalassemia (HBA1 and HBA2) Deletion/Duplication with reflex to Hb Constant Spring
Also known as: HBA DDCS
Use
The test is a preferred first-tier genetic test for confirming suspected alpha thalassemia or alpha thalassemia trait. It is used to detect common as well as rare and novel deletions or duplications of the alpha globin gene cluster, including the hemoglobin Constant Spring (HbCS) variant. The disorder affects synthesis of the alpha chain of hemoglobin, leading to varying clinical outcomes from asymptomatic carriers to severe anemia and stillbirth. Heterozygosity for HbCS is often asymptomatic, while homozygosity may lead to hemolytic anemia, jaundice, and splenomegaly.
Special Instructions
New York state approval requires submission of informed consent for genetic testing by NY patients. Genetic consultation is recommended.
Limitations
This test may not detect single exon deletions or duplications if breakpoints differ from those covered. Nondeletional variants in coding or regulatory regions, apart from HbCS, are not targeted. Individuals carrying both a deletion and duplication may appear normal in terms of alpha globin gene copies. Syndromic or acquired forms of alpha thalassemia associated with ATRX gene variants are not detected.
New York Approved
Methodology
Other
Biomarkers
LOINC Codes
- 55234-9
Result Turnaround Time
10-14 days
Related Documents
For more information, please review the documents below
Specimen
Whole Blood
Volume
2 mL
Minimum Volume
1 mL
Container
Lavender (EDTA), pink (K2EDTA), or yellow (ACD solution A or B)
Storage Instructions
Refrigerated. Also acceptable: Ambient.
Stability Requirements
| Temperature | Period |
|---|---|
| Room Temperature | 1 week |
| Refrigerated | 1 month |
| Frozen | Unacceptable |