Aids in determining the cause of elevated HbF. Test confirms suspected deletional HPFH.
- Patient Preparation
- Lavender (EDTA) or pink (K2EDTA). Also acceptable: Yellow (ACD Solution A or B), lt. blue (sodium citrate), or green (sodium or lithium heparin).
- Specimen Preparation
- Transport 3 mL whole blood. (Min: 1 mL)
- Storage/Transport Temperature
- Unacceptable Conditions
- Ambient: 72 hours; Refrigerated: 1 week; Frozen: Unacceptable
Characteristics: HPFH is a clinically benign condition resulting from mutations within the beta globin gene cluster that alter normal hemoglobin switching and result in persistent production of hemoglobin F (Hb F). Individuals heterozygous for an HPFH deletion typically have elevated levels of Hb F with normal red blood cell indices, while homozygotes typically have Hb F levels approaching 100 percent and mild erythrocytosis. When an HPFH deletion is paired with another beta globin gene mutation, variable phenotypes can result.
Incidence: Varies depending on the population.
Cause: Beta globin gene cluster deletions and point mutations within the promoter of the gamma globin genes.
Mutations Tested: HPFH-1 (g.5174452_5259368del84917), HPFH-2 (g.5180404_5263982del83579), HPFH-3 (g.5215683_5265453del49771), HPFH-4 (g.5217940_5260078del42139), HPFH-5 (g.5246023_5258951del12929), HPFH-6 (g.5193975_5273259del79278), HPFH-7 (g.5247860_5270651del22792), and SEA-HPFH (g.5222878_5250288del27411).
Clinical Sensitivity: Unknown.
Methodology: Multiplex PCR and gel electrophoresis.
Analytic Sensitivity: Greater than 95 percent for the 8 targeted HPFH deletions.
Limitations: Only the 8 targeted deletions associated with HPFH will be interrogated. Point mutations or rare deletions that cause HPFH or delta/beta thalassemia will not be identified. Other genetic modifiers of Hb F levels will not be assessed. This test will not differentiate homozygosity for an HPFH deletion from an HPFH deletion paired with a rare globin gene cluster deletion. Diagnostic errors can occur due to rare sequence variations.
Counseling and informed consent are recommended for genetic testing. Consent forms are available online.
|Component Test Code*||Component Chart Name||LOINC|
|2005409||Hereditary Persistent Fetal Hb Specimen|
|2005412||Hereditary Persistant Fetal Hb Interp|
- Carrier testing for HPFH
- HPFH molecular assay
- HPFH mutation assay