preconceptual testing for haemoglobinopathies

Last edited 07/2018 and last reviewed 09/2021

Pre-conceptual testing for haemoglobinopathies is recommended in at-risk groups (see below).

• Pre-conceptual testing is important because it can be difficult to complete antenatal screening and fetal diagnosis within the first 12 weeks of pregnancy if the couple is unaware of the risk. This is most likely to be feasible in general practice but other medical practitioners should be alert to the possibility of a carrier state for a haemoglobinopathy and should offer screening. The individuals concerned must be informed of the result, whether or not an abnormality is found
  • if an abnormality is detected (Hb variant or possible/probable thalassaemia), partner testing should be offered if appropriate
    
    
• Pre-conceptual testing should always be performed in women being investigated for infertility and in those having assisted conception. If a woman is found to have or be a carrier for a significant haemoglobinopathy, the partner or other sperm donor should be tested, if appropriate, and the women given counselling. If a donor ovum is to be used, the donor should be screened for relevant haemoglobinopathies
  
  
• Pre-marriage screening for haemoglobinopathies is not usual in the UK but for some religious/ethnic groups premarital screening for beta thalassaemia heterozygosity may be more acceptable than pre-conceptual or antenatal screening.

Ethnic groups with a clinically significant prevalence of haemoglobin S (sickle cell gene) and alpha 0 (see notes) and beta thalassaemia

• Haemoglobin S
  • african including North Africans, African-Caribbeans, African-Americans, Black British and any other African ethnicity (e.g. Central and South Americans of partly African ethnicity), Greeks, Southern Italians including Sicilians, Turks, Arabs, Indians
• alpha 0 thalassaemia
  • Chinese, Taiwanese, South-East Asian (Thai, Laotian, Cambodian, Vietnamese, Burmese, Malaysian, Singaporean, Indonesian, Philippino), Cypriot, Greek, Turkish and Sardinian
• beta thalassaemia
  • all ethnic groups other than Northern Europeans

Notes:

• the haplotype --/ (ie one chromosome pair having both alpha globin genes deleted) is known as alpha 0
• the haplotype -alpha/ (ie one chromosome pair having a single alpha globin gene deleted) is known as alpha+

Reference:

• (1) Ryan K et al. Significant haemoglobinopathies: guidelines for screening and diagnosis. British Journal of Haematology 2010: 149 (1): 35-49