Alpha Hemoglobin DNA Sequence

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General Information

Lab Name
Alpha Hemoglobin DNA Sequence
Lab Code
HASEQ
Epic Ordering
ALPHA HEMOGLOBIN DNA SEQUENCE
Description

There are currently over 800 hemoglobin variants catalogued, of which approximately 300 are due to mutations in the alpha-globin gene. In addition, approximately 5% of alpha-thalassemia is caused by point mutations. This test, which sequences the coding regions and introns of both the alpha-globin 1 (HBA1) and alpha-globin 2 (HBA2) genes in both directions, identifies hemoglobin variants that are not easily diagnosed by electrophoresis/HPLC and can determine the cause of non-deletional alpha-thalassemia.

Indications for testing include:

  • Identification of hemoglobin variants detected by electrophoresis or HPLC
  • Differential diagnosis of microcytic anemia
  • Evaluation of nondeletional Hemoglobin H disease
  • Evaluation of a relative of an individual with a known alpha-globin mutation
  • Prenatal diagnosis of nondeletional alpha-thalassemia in pregnancies at risk for Hb H hydrops fetalis syndrome

NOTE: For outside patients please provide additional clinical and family history. Please include the following available laboratory data: CBC, Hb electrophoresis, and iron studies.

Notes: To order testing for a relative of an individual with a known alpha-globin mutation, see the Laboratory Medicine Online Test Guide for Alpha Hemoglobin Sequencing, Relative [HAREL]. If testing for deletional alpha-thalassemia is indicated, order “Alpha Thalassemia DNA Screen”.

References
  • Huisman, T. H. J., Carver, M. F. H., and Efremov, G. D. (1996). A Syllabus of Hemoglobin Variants (Augusta, GA: The Sickle Cell Anemia Foundation).
  • Higgs DR, et al. A review of the molecular genetics of the human alpha-globin gene cluster. Blood 1989, 73:1081-104. 2649166 .
  • Skogerboe KJ, et al. Screening for alpha-thalassemia. Correlation of hemoglobin H inclusion bodies with DNA-determined genotype. Arch Pathol Lab Med 1992, 116:1012-8. 1329692
  • Molchanova TP, Pobedimskaya DD, and Postnikov YuV. A simplified procedure for sequencing amplified DNA containing the alpha 2- or alpha 1-globin gene. Hemoglobin 1994, 18:251-5. 7928384
  • Old JM. Screening and genetic diagnosis of haemoglobin disorders. Blood Rev 2003, 17:43-53. 12490210
  • Chui DH, Fucharoen S, and Chan V. Hemoglobin H disease: not necessarily a benign disorder. Blood 2003, 101:791-800. 12393486
  • Chan V, et al. Molecular defects in Hb H hydrops fetalis. Br J Haematol 1997, 96:224-8. 9029003
  • Globin Gene Server: http://globin.cse.psu.edu/
Forms & Requisitions

Genetics Requisition

Synonyms
Alpha Thalassemia, Constant Spring, Globin, Hemoglobin Bart's, Hemoglobin H, Hemoglobinopathy, Hydrops fetalis
Components

Interpretation

Method

DNA sequencing of the coding regions and introns of both the alpha1 (HBA1) and alpha 2 globin (HBA2) genes in both directions to detect point mutations causing alpha globin variants and some types of alpha thalassemia.

This test detects alpha globin variants and non-deletional alpha thalassemia mutations (e.g. Hb Constant Spring). The coding regions and introns of both HBA1 and HBA2 genes are sequenced in bidirectionally. The reference mRNA sequences are HBA1 (NM_000558.3) and HBA2 (NM_000517.4) with nucleotide 1 corresponding to the A of the AUG initiation codon (nucleotide 38 of both reference sequences) and codon 1 corresponding to the valine encoded by GTG (nucleotides 41-43 of both reference sequences). The sensitivity of this test for detecting nucleotide substitutions, small insertions and deletions and in the alpha 1 (HBA1) and alpha 2 (HBA2) genes is theoretically >98%. This test will not detect mutations that lie outside of the sequenced regions, nor large HBA1 and HBA2 gene deletions (e.g. –a3.7, – –SEA). This test was developed and its performance characteristics determined by the Department of Laboratory Medicine at the University of Washington.

Reference Range
See individual components
Ref. Range Notes

No mutation detected.

References
  • Huisman, T. H. J., Carver, M. F. H., and Efremov, G. D. (1996). A Syllabus of Hemoglobin Variants (Augusta, GA: The Sickle Cell Anemia Foundation).
  • Higgs DR, et al. A review of the molecular genetics of the human alpha-globin gene cluster. Blood 1989, 73:1081-104. 2649166 .
  • Skogerboe KJ, et al. Screening for alpha-thalassemia. Correlation of hemoglobin H inclusion bodies with DNA-determined genotype. Arch Pathol Lab Med 1992, 116:1012-8. 1329692
  • Molchanova TP, Pobedimskaya DD, and Postnikov YuV. A simplified procedure for sequencing amplified DNA containing the alpha 2- or alpha 1-globin gene. Hemoglobin 1994, 18:251-5. 7928384
  • Old JM. Screening and genetic diagnosis of haemoglobin disorders. Blood Rev 2003, 17:43-53. 12490210
  • Chui DH, Fucharoen S, and Chan V. Hemoglobin H disease: not necessarily a benign disorder. Blood 2003, 101:791-800. 12393486
  • Chan V, et al. Molecular defects in Hb H hydrops fetalis. Br J Haematol 1997, 96:224-8. 9029003
  • Globin Gene Server: http://globin.cse.psu.edu/
Guidelines

Ordering & Collection

Specimen Type
Blood, amniocytes, chorionic villus tissue or cultured cells.
Collection

BLOOD:

  • Adult: 5 mL LAVENDER TOP tube
  • Child: 2 mL LAVENDER TOP tube
  • Also acceptable: YELLOW TOP (ACD) tube
  • Unacceptable: Heparin green top tubes

AMNIOCYTES or CULTURED CHORIONIC VILLUS CELLS:

  • Two (2) T23 or One (1) T75 flask (minimum 1-T25 flask)

CHORIONIC VILLIS and/or TISSUE:

  • In sterile tube or culture media, at least 5 mg tissue.

Prenatal testing requires concomitant testing for maternal cell contamination (see Online Test Guide, Lab Mnemonic Maternal Cell Contamination [MCC] for ordering and specimen requirements)

NOTE: For outside patients please provide additional clinical and family history. Please include the following available laboratory data: CBC, Hb electrophoresis, and iron studies.

Forms & Requisitions

Genetics Requisition

Handling Instructions

Blood: Refrigerate whole blood up to 1 week.

Amniocytes & cultured CVS cells: hold flasks at room temperature.

Chorionic villi &/or tissue: hold at room temperature.

Outside Laboratories: Ship whole blood at ambient temperature for receipt within 1 week of specimen collection. - For cultured amniocytes or chorionic villus cells and for CVS or other tissue, transport and store at room temperature within 24 hours of obtaining CV or removing cultured cells from incubator.

Quantity
requested: Entire specimen
minimum: Blood: 1 mL. Amniocytes, cultured chorionic villus cells, chorionic villi or tissue: as above.

Processing

Processing

Processing: Please notify genetics about amniocytes, cultured chorionic villus cells, chorionic villi or tissue.

Performance

LIS Dept Code
Genetics (GEN)
Performing Location(s)
UW-MT Genetics

Attention: Genetics Lab
Clinical lab, Room NW220
University of Washington Medical Center
1959 NE Pacific Street
Seattle, WA 98195

Tel: 206-598–6429 M–F (7:30 AM–4:00 PM)
Fax: 206-598–0304
Lab email: genelab@uw.edu

Tel (EXOME only): 206-543-0459

Manager

Rebecca Gaulin, rgaulin@uw.edu

Genetic Counselors

Angela Jacobson, MS, LGC agibson@uw.edu
Sarah Paolucci, MA, MS, LGC, spaolucc@uw.edu
Jenna Huey, MS, LGC, jlhuey@uw.edu
Sandra Coe, MS,LGC, scoe20@uw.edu
Dru Leistritz, MS, LGC, dru2@uw.edu (EXOME testing only)

Variant Review Scientist

Ankita Jhuraney, PhD

Faculty

Colin C. Pritchard, MD, PhD
Brian H. Shirts, MD, PhD
Christina Lockwood, PhD, DABCC
Stephen Salipante, MD, PhD
Eric Konnick, MD, MS
Niklas Krumm, MD,PhD
Vera Paulson, MD, PhD
Jillian Buchan, PhD, FACMG

Frequency
Performed weekly. Results within 3 weeks.
Available STAT?
No

Billing & Coding

CPT codes
81259
Billing Comments

For pricing information, contact Client Support Services 206-520-4600 or 800-713-5198.

LOINC
60540-2