Beta thalassaemia

Purpose of the test

Beta thalassaemia is characterised by a reduction ( β+) or absent ( β0) production of the beta chains of the haemoglobin tetramer. This results in an imbalance of the alpha:beta chain ratio, resulting in excess alpha chains that cause haemolysis. The large majority of these defects are single nucleotide substitutions affecting genetic loci critical to the function of the beta globin gene. Carriers of beta thalassaemia have one normal beta globin gene and one with a beta thalassaemia mutation. The phenotypic indices show an elevated red blood cell count, the MCV is lowered to 60-75fl, the MCH is reduced to 20-25pg and the Hb A2 concentration is increased to 3.5 - 7.0%. Individuals with two defective beta globin genes are often blood transfusion dependent (beta thalassaemia major). The severity of the disease is related to the type of mutations carried. Identification of the beta thalassaemia mutations is by beta globin gene sequencing or by direct mutation analysis if the mutation is known.

Sample Requirements

Volume of blood anticoagulated with EDTA:

Adult (16 years and above) 10-15 mls

Children (2-15 years) 5 mls

Infants (0-2 years) 2 mls

Presence of heparin anticoagulant will inhibit PCR applications.

Clotted samples are unsuitable for DNA analysis.

For prenatal diagnosis please refer to section for sample requirements.

Storage and Transport

Blood should be stored at 4°C where possible. Send at room temperature by first class post.

If possible, please complete the request form attached and send as a hard copy (do not send electronically) with the sample. This will ensure all relevant information is available and will aid us in processing your test.

PDF Request Form

Download Beta Thalassaemia Request Form

Turnaround Time

Routine samples 4-6 weeks

DNA analysis in antenatal patients 2 weeks

Time Limit for Extra Tests

5 years

Factors affecting results or interpretation

Presence of heparin anticoagulant will inhibit PCR applications.

Clotted samples are unsuitable for DNA analysis.

Samples must be clearly labelled with the patients first name, surname, D.O.B, hospital number and the date the sample was taken. The details on the sample must correspond to the request form. Unlabelled samples will not be accepted.