乙型 (β) 地中海貧血遺傳基因測試

What is beta-thalassemia?

Beta-thalassemia (β-thalassemia) is the most common haemoglobin disorder found in the Mediterranean area and is estimated to affect 5 – 10 % of the Asian population. Affected individuals have low levels of hemoglobin leading to shortage of red blood cells (anemia), which can cause pale skin, weakness, fatigue, and more serious complications. 

What causes β-thalassemia?

β-thalassemia is caused by mutations of the β-globin gene (HBB), resulting in defective (+) or absent (0) production of β-globin. A lack of β-globin leads to a reduced amount of functional hemoglobin and results in anemia. Depending on the clinical severity of the disease, it can be classified into β-thalassemia major, intermedia or minor.

How is β-thalassemia inherited?

Each person inherits 2 copies of the HBB gene, one from each parent. People with only 1 copy of the gene altered typically do not show any symptoms and are carriers of HBB gene mutations. However, some carriers have mild anaemia. If both parents are carriers, their offspring has a 25% chance of having a severe form of β-thalassemia (2 altered copies of HBB gene); a 50% chance of having a mild form of β-thalassemia (1 altered copy of HBB gene); and a 25% chance of being normal (no mutations). Children affected by severe forms of β-thalassemia would develop severe anaemia in infancy and would require frequent blood transfusion.

What is this test for?

This test detects the most common 21 mutations of the HBB gene (>95%) found in the Chinese and Southeast Asian population.

Who should consider this test?

  • Patients with abnormal hematological findings
  • Confirmatory testing for individuals who suspect of carrying defective β-thalassemia gene
  • Family planning for couples at risk in hemoglobin disorder
  • Prenatal diagnosis 

測試詳情

測試代碼
測試方法
樣本要求
測試所需時間
GBT
桑格 (Sanger) 基因測序
10 mL amniotic fluid; or 20 mg chorionic villi; or 3 mL blood in EDTA tube
10 days

Rejection criteria

  • Specimen without proper labeling
  • Specimen not in requested format or insufficient quantity
  • Specimen in container expired for more than 1 month
  • Container leakage
  • Sampling date is more than 7 days
  • Frozen specimen, haemolysed or clotted blood specimen

Factor(s) known to affect results

  • Improper collection, handling and storage of specimen

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