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Fetal and Women's Health

Presentation: Pregnancy in which the mother is diagnosed with, or is a known carrier of, a haemoglobinopathy disease

Haemoglobin conditions, such as sickle cell disease and thalassaemia, are often detected during pregnancy or soon after birth. Pregnant women who have or are carriers of a haemoglobin condition may benefit from genomic testing.

Example clinical scenario

A pregnant woman attends an antenatal clinic. She is concerned because results from the sickle cell screening test she consented to (as part of her recent antenatal booking appointment) have shown that she is a carrier of an atypical haemoglobin or variant.

When to consider genomic testing

  • If a pregnant woman is found to be have or be a carrier of sickle cell disease or thalassaemia, or has had an inconclusive screening result, the biological father should be offered screening.
    • Testing may be a haematological screen (with a blood film) or a genomic test.
    • Often, assessing for sickle cell carrier status does not require genomic testing because it is possible to diagnose using routine haematological investigations.
  • If both parents are carriers of genetic variants that cause a significant haemoglobinopathy, prenatal testing should be considered.

What do you need to do?

  • Collect a detailed family, medical and clinical history from the couple if the mother is affected with sickle cell disease.
    • In addition, a family origin questionnaire that includes information on the family origins of the woman and the baby’s biological father should accompany the full blood count and haemoglobinopathy screening sample. This enables laboratory clinical scientists to interpret results.
  • NHS England has published comprehensive guidelines on when to refer for molecular testing (see the sickle cell and thalassaemia antenatal laboratory handbook). This process is designed to identify couples at risk of severe haemoglobinopathies so that prenatal diagnosis can be performed in a timely fashion.
  • Follow local protocols to determine appropriate onward referral.
  • The relevant team will refer to the NHS England National Genomic Test Directory eligibility criteria to determine which tests are available. The directory itself provides a list of all available tests.
  • Genomic testing options depend on the specific variant(s), but may include the below.
    • Carrier screening for the pregnant woman and the biological father:
      • R361 Sickle cell, thalassaemia and other haemoglobinopathies trait or carrier testing. This test is for individuals who are likely to have or carry a clinically significant haemoglobinopathy (other than sickle cell disease) based on initial protein testing.
        • This test requires blood to be collected in an EDTA tube. Refer to your local Genomic Laboratory Hub for details of test request forms and where to send samples.
    • Prenatal invasive testing may be offered in pregnancies with a known familial disease-causing variant.
      • Referral to a fetal medicine unit is required.
  • A completed record of discussion form, or an alternative local consent form, will be required by the laboratory to process the sample.
  • Information about patient eligibility and test indications was correct at the time of writing. When requesting a test, please refer to the National Genomic Test Directory to confirm the right test for your patient.

Resources

For clinicians

References:

For patients

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  • Last reviewed: 10/09/2024
  • Next review due: 10/09/2025
  • Authors: Sally Boxall
  • Reviewers: Heidy Brandon, Donna Kirwan, Dr Jessica Woods

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