Screening

Carrier screening before and during pregnancy

UK guidelines recommend considering preconception testing (or premarital testing, if appropriate) for haemoglobinopathies in individuals of childbearing age who are considered high risk due to family origin.[44]

Thalassaemia screening is recommended for all women in the UK during early pregnancy (before 10 weeks’ gestation). Screening for alpha-thalassaemia aims to identify pregnancies in which both parents are alpha(0) thalassaemia carriers and the baby is at risk of alpha-thalassaemia major. If antenatal screening suggests that the mother is an alpha(0) thalassaemia carrier, testing is offered to the biological father if he is considered high risk (based on assessment of family origin). DNA testing is required to confirm alpha-thalassaemia status.[40]

The American College of Obstetricians and Gynecologists recommends universal haemoglobinopathy testing for those planning pregnancy.[39][42]​​ Haemoglobin electrophoresis or molecular genetic testing should be performed when planning pregnancy, or at the initial antenatal visit if there are no previous test results available.[39] If a woman is found to be a carrier, her reproductive partner should be offered screening.[42] Information and counselling should be offered alongside screening.[42][43]

Thorough genetic counselling, including a discussion of reproductive options (including pre-implantation genetic testing or prenatal diagnosis) should be offered to all individuals who test positive during screening.[45][39]

Antenatal diagnosis

Pre-implantation genetic testing to prevent a pregnancy with alpha-thalassaemia major is an option for prospective parents considering in vitro fertilisation.[37][45]

Available tests for patients with an at-risk pregnancy include chorionic villus sampling (typically performed at 10-12 weeks' gestation in the US; 11-14 weeks' gestation in the UK) and amniocentesis (typically performed after 15 weeks' gestation).[36]​​[37][45]​​ These are invasive tests and carry a risk of fetal loss.

Ultrasound is an important non-invasive means of detecting alpha-thalassaemia major in at-risk pregnancies and may reduce the need for invasive testing.​​[60][61][62]​ It is usually performed relatively late in pregnancy.​

Non-invasive prenatal testing (NIPT) of cell-free fetal DNA in maternal circulation is emerging as a antenatal screening test for haemoglobinopathies such as thalassaemia and sickle cell disease.[39][63][64]​ NIPT may be considered as a screening test to detect alpha-thalassaemia major, used in combination with established methods for fetal diagnosis.[16]

Newborn screening

Alpha-thalassaemia is not included in the United States Recommended Uniform Screening Panel for state newborn screening programmes. However, current screening methodologies used to detect sickle cell disease (reported by all states) also detect alpha-thalassaemia.[35]

Asymptomatic patient with microcytosis

Screening can be performed in an asymptomatic patient with mild anaemia and microcytosis to establish a diagnosis and thus avoid unnecessary and perhaps even harmful iron supplementation.

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