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Test ID: Beta-Thalassemia
Beta-Thalassemia
Targeted and full HBB gene sequencing
Useful For

HBB full-gene sequencing is performed to detect all clinically relevant variants in the β-globin gene, including point mutations, small insertions, and deletions that may not be identified by routine screening methods. This test helps confirm the diagnosis of β-thalassemia and other hemoglobinopathies, especially in cases where CBC, hemoglobin electrophoresis, or HbA₂ levels are inconclusive.

It is also useful for carrier screening, premarital testing, and family studies to determine the inheritance of known or suspected β-globin variants. Full sequencing supports accurate genetic counseling by identifying both common and rare mutations, enabling proper assessment of reproductive risk and clinical management.
Method name and description

PCR of exons, introns and 5 and 3-prime UTRs of hemoglobin beta gene (HBB), followed by bidirectional capillary DNA sequencing. Results may be compromised in presence of rare sequence variations.
Reporting name

Beta-Thalassemia

Clinical information

Beta thalassemia is an inherited blood disorder caused by variant in the beta-globin gene (HBB), leading to reduced or absent production of beta-globin chains, a critical component of hemoglobin. This results in an imbalance between alpha and beta chains, causing ineffective erythropoiesis and chronic hemolytic anemia. The clinical severity of beta thalassemia varies based on the specific mutation and ranges from mild to severe anemia. The three main types of beta thalassemia are:

Beta thalassemia minor (trait): Mild anemia, typically asymptomatic.

Beta thalassemia intermedia: Moderate anemia with variable symptoms.

Beta thalassemia major: Severe anemia requiring regular blood transfusions and other interventions.

Prevalence: The prevalence of beta thalassemia is highest in populations from the Mediterranean, Middle East, Southeast Asia, and parts of Africa and South Asia.

Inheritance: Beta thalassemia is inherited in an autosomal recessive manner. Everyone inherits two beta-globin genes, one from each parent. Clinical severity depends on whether one or both genes are affected and whether the mutation is a beta+ (reduced beta-globin production) or beta0 (absent beta-globin production) mutation.

  • Beta thalassemia trait (heterozygous mutation): One gene carries a variant, typically mild or asymptomatic.
  • Beta thalassemia intermedia or major (homozygous or compound heterozygous mutation): The two gene alleles carry a variant, leading to moderate to severe anemia.
Aliases

HBB full gene sequence

Thalassemia

Beta thalassemia minor

Beta thalassemia major

Targeted and full HBB gene sequencing
Specimen type / Specimen volume / Specimen container

Specimen Type

Specimen Volume

Container/Tube

Whole Blood

Adult: minimum 3 mL

Child : minimum 1ml

 

Lavender top (EDTA)

DNA

minimum 2-3 µg

2ml sterile cryovial
Collection instructions / Special Precautions / Timing of collection

Collection Instruction

Note: This is a "one-time " test. This means that the test is typically performed once and does not need to be repeated unless there are specific circumstances or changes in health status that warrant it.

 

Patient Preparation: Previous allogeneic bone marrow transplant can yield discordant leukocyte DNA; note clearly in clinical details.

Specimen Type: Whole blood or DNA from CAP/ISO or similar accredited laboratories is acceptable.

 

Specimen Type

Container/Tube

Volume Required

Patient Preparation / Notes

Whole Blood (EDTA)

Lavender-top EDTA tube

Adult: ≥3 mL    Child: ≥1 mL

No fasting required. Note prior bone marrow transplant or transfusion.

Extracted DNA

Sterile microcentrifuge tube

≥50 ng/µL concentration; minimum 20 µL

DNA must be from patient’s own tissue; provide extraction method if from external lab
 
Relevant clinical information to be provided

Submit With Order

Specimen Requirement / Pre-Analytical Requirements:

  • Mandatory preliminary tests:
    • Complete Blood Count (CBC) including MCV and MCH
    • Hemoglobin Electrophoresis or HPLC (HbA2, HbF levels, and variant hemoglobin detection)
  • Sequencing will only be performed if preliminary results indicate abnormal hemoglobin pattern or microcytosis/hypochromia suggestive of hemoglobinopathy.
  • Clinical indication and relevant history
  • Family history
  • Document prior allogeneic bone marrow transplant (may confound results).
  • Genetic counseling and informed consent are recommended.
Storage and transport instructions

The specimens should be transported to Central Processing (CP) in the Qatar Rehabilitation Institute (QRI), 3rd floor, HBK MC in cool box with ice pack.

 

Specimen Type

Container/Tube

Volume Required

Storage Before Transport

Transport

Conditions

Whole Blood (EDTA)

Lavender-top EDTA tube

Adult: ≥3 mL    Child: ≥1 mL

Room temperature ≤24h; 2–8 °C preferred if delay expected

2–8 °C (refrigerated), upright, avoid shaking; ≤72 hours

Extracted DNA

Sterile microcentrifuge tube

≥50 ng/µL concentration; minimum 20 µL

2–8 °C (preferred) for short term. –20 °C or lower for long-term storage

2–8 °C (preferred) or Room Temp ≤5 days if stabilized;
Specimen Rejection Criteria
  • Specimens will be rejected under the following conditions:
  • Wrong specimen container.
  • Leaking or contaminated container.
  • Unlabeled specimen.
  • Mislabeled specimen.
  • Improperly filled request form.
  • No specimen types.
  • No physician stamps.
  • No clinical history/data documented.
  • The information written on the tube does not match the data on the request form, and there is no response when calling the ward for correction.
  • No request form/electronic order received.
  • Excessive hemolysis or clotted blood.
  • Delayed specimens that are judged unsuitable for analysis.
Biological reference intervals and clinical decision values

Biological reference intervals and clinical decision values

An interpretive report will be provided.
Turnaround time / Days and times test performed / Specimen retention time

Turn Around Time

3 weeks for targeted variants (Working Days: Sunday to Thursday)

10 weeks (Working Days: Sunday to Thursday)

 

Specimen Retention Time

Whole Blood: Aliquots stored >2 years (if available)

Extracted DNA: Lifetime (if available)

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