Thalassaemia

Last updated: Thursday, 23, December, 2010
Key InformationAppropriate Tests

FBC, Blood film, Red cell indices (especially MCV ), Haemoglobin electrophoresis, Haemoglobin A2, Haemoglobin F estimation, Haemoglobin H inclusions.

Iron deficiency may coexist with heterozygous thalassaemias, particularly during growth periods and pregnancy.

Iron deficiency should be treated prior to investigation for thalassaemia, as otherwise a false negative result may be found.

See also Haemoglobinopathy

Beta thalassaemia

Normal individuals have one paternal and one maternal ß globin gene (ß /ß).

Heterozygous (thalassaemia trait)

Spouse/partner should also be tested.

Homozygous (thalassaemia major)

Ferritin to assess iron stores, as Haemosiderosis occurs if transfusion therapy is not associated with adequate iron chelation therapy.

The severity varies, and some patients in which the thalassaemic mutation reduces but does not eliminate ß globin production, or patients with high haemoglobin F, may have a milder phenotype, and not be transfusion dependent (thalassaemia intermedia).

Double heterozygous ie multiple haemoglobinopathies(thal major or intermedia).

Alpha thalassaemia

Spouse/partner should also be tested. Normal individuals have four globin genes, inherited as a block of two alpha genes from mother and father, making the genetics of alpha thalassaemia more complicated than beta thalassaemia. 

Heterozygous α+ (α-/αα)

This is associated with a normal phenotype or very mild microcytosis.

Heterozygous α0 (--/αα)

This has a thalassaemia trait phenotype (mild microcytic anaemia).

Homozygous α+ (α-/α-)

This has a thalassaemia trait phenotype (mild microcytic anaemia).
  • Haemoglobin H disease (--/-α)
Typically the haemoglobin is ~80 g/L with a severe microcytosis. Patients are usually well, transfusion independent, but may develop iron overload. 

Homozygous α0 (--/--)

This is not compatible with life, and typically results in early miscarriage or third trimester hydropic fetus and fetal death. 
  • Hydrops fetalis
See Haemoglobin Barts hydrops fetalis syndrome under Hydrops fetalis.

Prenatal diagnosis

See Molecular genetics - individual genetic disorders