Table 2. Sickle cell disorders—interactions and indications for prenatal diagnosis and preimplantation genetic diagnosis (PGD).
| Genotype interaction | Disorder expected | Appropriate to offer PND |
|---|---|---|
| Homozygous | ||
| Hb S | Sickle cell disease | Yes |
| Compound heterozygous | ||
| Hb S/β° or severe β+-thalassaemia | Sickle cell disease | Yes |
| Hb S/mild β+-thalassaemia | Mild sickle cell disease | Occasionallya |
| Hb S/δβ°-thalassaemia | Mild sickle cell disease | Occasionallya |
| Hb S/Hb Lepore | Mild sickle cell disease | Occasionallya |
| Hb S/HbC | Sickle cell disease (variable severity) | Yes |
| Hb S/Hb D-Punjab | Sickle cell disease | Yes |
| Hb S/Hb O-Arab | Sickle cell disease | Yes |
| Hb S/Hbs C-Harlem, S-Southend, S-Antilles | Sickle cell disease | Yes |
| Hb C/Hb S-Antilles | Sickle cell disease | Yes |
| Hb S/Hbs Quebec-Chori, C-Ndjamena, O-Tibesi | Sickle cell disease | Yes |
| Hb S/Hbs I-Toulouse, Shelby, Hope, North Shore | Haemolytic anaemia | No |
| Hb S/Hb E | Mild to severe sickle cell disease | Occasionallya |
| Hb S/HPFH | Very mild sickle cell disease | No |
Note: The decision to have prenatal diagnosis belongs to the couple, once they have had comprehensive counselling.
a
Couples with genotypes that may lead to offspring with unpredictable phenotypes occasionally select to have prenatal diagnosis or PGD.