Reference Interval:
By report
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| Interpretive Data: |
Background Information for Alpha Thalassemia (HBA1 & HBA2) 7 Deletions:
Characteristics: Alpha (+) thalassemia (silent carrier): Mutation of a single alpha2 globin gene (-α/αα); asymptomatic. Alpha (0) thalassemia (trait): Mutation of both alpha2 globin genes, or deletion of alpha1 and alpha2 globin genes in cis (-α/-α; --/αα); mild microcytic anemia possible. Hemoglobin H disease: Mutation of three alpha globin genes (--/-α); hemolysis with Heinz bodies, moderate anemia, and splenomegaly. Hb Bart Hydrops Fetalis Syndrome: Mutation of four alpha globin genes (--/--); lethal in fetal or early neonatal period.
Incidence: Carrier frequency in Mediterranean (1:30-50), Middle Eastern, Southeast Asian (1:20), African, African-American (1:3).
Inheritance: Autosomal recessive.
Cause: Mutations in the alpha globin gene cluster; 95 percent are deletions.
Mutations Tested: -α3.7, -α4.2, -(α)20.5, --SEA, --MED, --FIL, --THAI
Clinical Sensitivity: Varies by ethnicity, may be as high as 90 percent.
Methodology: Polymerase chain reaction and gel electrophoresis.
Analytical Sensitivity and Specificity: Greater than 99 percent.
Limitations: Rare alpha globin gene deletions, non-deletion mutations, gene duplications, and mutations of the regulatory region will not be detected.
Counseling and informed consent are recommended for genetic testing. Consent forms are available online at www.aruplab.com.
Refer to Statement C under Testing Information at http://www.aruplab.com.
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| CPT Code(s): |
83891 Isolation; 83900 Amplification multiplex; 83901 x8 Additional amplification; 83894 Gel separation; 83912 Interpretation and report - Additional CPT code modifiers may be required for procedures performed to test for oncologic or inherited disorders.
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