Thalassaemia Testing | Alpha & Beta Thalassaemia | Cytogenomix® Malaysia
Haemoglobinopathy Testing

Thalassaemia Testing

Comprehensive molecular analysis for alpha and beta thalassaemia. Carrier screening, diagnostic testing, and prenatal diagnosis for this common inherited blood disorder in Malaysia.

α+β ALPHA & BETA
500+ MUTATIONS
3-5% CARRIER RATE
7-10 DAYS TAT

Test Specifications

Technical details for thalassaemia genetic testing

Test Code THAL001 (Alpha), THAL002 (Beta), THAL003 (Comprehensive Panel)
Methodology Gap-PCR for common deletions, Sanger sequencing for point mutations, MLPA for rare deletions
Genes Analyzed HBA1, HBA2, HBB, and regulatory regions
Mutations Detected –SEA, –α3.7, –α4.2, αααanti3.7, Hb Constant Spring, Hb Quong Sze, common beta mutations (IVS1-5, IVS1-1, IVS1-6, codon 41/42, codon 17, etc.)
Sample Type 3-5 mL whole blood (EDTA purple top) | Prenatal: Amniotic fluid/CVS
Turnaround Time 7-10 working days (blood) | 10-14 days (prenatal)
Reporting ISCN-compliant molecular report with genotype-phenotype correlation
Genetic Counseling Pre- and post-test counseling included

Understanding Thalassaemia

Thalassaemia is an inherited blood disorder characterized by reduced or absent synthesis of the globin chains of haemoglobin. It is one of the most common genetic disorders worldwide, with particularly high prevalence in Malaysia and Southeast Asia.

Types of Thalassaemia:

  • Alpha Thalassaemia: Reduced synthesis of alpha-globin chains; severity ranges from silent carrier to Hb Bart's hydrops fetalis
  • Beta Thalassaemia: Reduced synthesis of beta-globin chains; includes thalassaemia minor (trait), intermedia, and major

In Malaysia, approximately 3-5% of the population are carriers of thalassaemia, with higher rates in certain ethnic groups.

Thalassaemia Inheritance

Thalassaemia in Malaysia

Epidemiology and public health impact

3-5%
Carrier Rate
1:500
Affected Births
α+β
Types
20+
Common Mutations

Carrier Frequency by Ethnic Group

Ethnic Group Alpha Thalassaemia Beta Thalassaemia HbE
Malay 4-5% 2-3% 3-4%
Chinese 5-6% 2-3% <0.5%
Indian 1-2% 3-4% 2-3%
Orang Asli 8-10% 3-4% 10-15%

Genotype-Phenotype Correlation

Understanding how genetic findings relate to clinical severity

Alpha Thalassaemia

Genotype Clinical Phenotype Severity
-α/αα (one gene deletion) Silent carrier; normal CBC, possible low MCV Asymptomatic
--/αα or -α/-α (two gene deletions) Alpha thalassaemia trait; microcytosis, hypochromia, mild anaemia Mild
--/-α (three gene deletions) Haemoglobin H disease; moderate to severe anaemia, splenomegaly Moderate
--/-- (four gene deletions) Hb Bart's hydrops fetalis; fatal in utero or at birth Severe

Beta Thalassaemia

Genotype Clinical Phenotype Severity
β/β (normal) Normal Asymptomatic
β/β⁺ or β/β⁰ (heterozygous) Beta thalassaemia trait; microcytosis, mild anaemia Mild
β⁺/β⁺ (compound heterozygous) Thalassaemia intermedia; variable anaemia, may require occasional transfusions Moderate
β⁰/β⁰ or β⁰/β⁺ (homozygous/compound) Thalassaemia major; severe anaemia, transfusion-dependent Severe
β/βᴱ (HbE/beta thalassaemia) Variable severity; most common in Southeast Asia Variable

Common Mutations in Malaysian Population

Our panel detects all clinically significant mutations

Alpha Thalassaemia

–SEA Southeast Asian deletion

–α3.7 3.7 kb deletion

–α4.2 4.2 kb deletion

αααanti3.7 Triplication

Hb CS Constant Spring

Hb QS Quong Sze

Beta Thalassaemia

IVS1-5 (G>C) Common in Chinese

CD 41/42 (-TTCT) Common in Chinese

CD 17 (A>T) Common in Chinese

IVS1-1 (G>T) Common in Indian

CD 8/9 (+G) Common in Indian

IVS1-6 (T>C) Common in Mediterranean

Haemoglobin Variants

HbE (G>A) Common in Southeast Asia

HbS (sickle) Sickle cell disease

HbC Common in West Africa

HbD Punjab Common in India

Autosomal Recessive Inheritance

Understanding the risk for couples who are carriers

Both Parents Carriers

Carrier
Carrier
Normal
Carrier
Carrier
Affected
25% risk affected child

50% carrier, 25% unaffected

One Parent Carrier

Carrier
Normal
Normal
Carrier
Normal
Carrier
50% carrier children

No affected children

For couples where both partners are carriers, prenatal diagnosis and PGT are available to prevent affected pregnancies.

Clinical Management

Treatment and monitoring options for affected individuals

Thalassaemia Major

  • Regular blood transfusions (every 2-4 weeks)
  • Iron chelation therapy (desferrioxamine, deferasirox)
  • Splenectomy if hypersplenism develops
  • Folic acid supplementation
  • Haematopoietic stem cell transplantation (curative)

Thalassaemia Intermedia

  • Intermittent transfusions as needed
  • Hydroxyurea to increase HbF
  • Folic acid supplementation
  • Monitoring for iron overload
  • Splenectomy if indicated

Monitoring

  • Regular FBC and haemoglobin electrophoresis
  • Ferritin levels every 3-6 months
  • Cardiac T2* MRI for iron overload
  • Liver iron concentration
  • Endocrine surveillance (growth, diabetes, thyroid)

Reproductive Options

  • Preconception carrier screening
  • Prenatal diagnosis (CVS/amniocentesis)
  • Preimplantation genetic testing (PGT)
  • Cascade testing for family members

Recommended Testing Algorithm

Step-wise approach to thalassaemia diagnosis

Full Blood Count
Hb Electrophoresis / HPLC
DNA Analysis
Genetic Counseling

Indications for direct DNA testing: Preconception screening, positive family history, partner of known carrier, abnormal RBC indices with normal iron studies, prenatal diagnosis

Who Should Be Tested?

Guidelines for thalassaemia carrier screening

Preconception Screening

All couples planning pregnancy, especially in high-risk populations

Family History

Individuals with family history of thalassaemia or haemoglobinopathy

Abnormal Blood Count

Microcytosis, hypochromia, or unexplained anaemia with normal iron studies

Prenatal Cases

Couples where both partners are carriers, for prenatal diagnosis

Frequently Asked Questions

Common questions about thalassaemia testing

What is the difference between alpha and beta thalassaemia?

Alpha thalassaemia affects alpha-globin chains (4 genes, HBA1/HBA2); beta thalassaemia affects beta-globin chains (2 genes, HBB). The inheritance patterns and molecular testing approaches differ.

Can thalassaemia be cured?

Haematopoietic stem cell transplantation is curative but requires a matched donor. Gene therapy is emerging as a potential curative option. Most patients require lifelong management.

What is HbE/beta thalassaemia?

This is the most common severe thalassaemia syndrome in Southeast Asia, caused by inheritance of HbE from one parent and beta thalassaemia from the other. Clinical severity varies widely.

If I'm a carrier, will I have symptoms?

Carriers (thalassaemia trait) are typically asymptomatic but may have mild microcytosis. No treatment is needed, but genetic counseling is important for reproductive planning.

Can thalassaemia be detected prenatally?

Yes, prenatal diagnosis is available through CVS (10-12 weeks) or amniocentesis (15-18 weeks) when both parents are carriers. PGT for IVF cycles is also available.

Do I need iron supplements if I have thalassaemia trait?

No. Iron deficiency and thalassaemia trait both cause microcytosis, but iron supplementation is not indicated for thalassaemia carriers. Iron studies should be checked to differentiate.

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