Alpha-Thalassemia: What Tests Does Your Partner Need?

When you know you are an alpha-thalassemia carrier and are planning to have a baby, your partner will need specific blood tests. The goal is to find out if they are also a carrier, which helps determine if your future child might be at risk for a severe form of alpha-thalassemia.

It is highly recommended to complete this screening before you become pregnant, as genetic testing can take several weeks to process. While some modern clinics offer comprehensive direct DNA panels (Expanded Carrier Screening) as a first step, many doctors still use a traditional, step-by-step approach starting with routine blood tests.

Step 1: The Complete Blood Count (CBC)

In a stepwise approach, the first test is a simple, inexpensive Complete Blood Count (CBC) ^[1]. This looks at the size and characteristics of red blood cells.

Your doctor will specifically look at two numbers:

• Mean Corpuscular Volume (MCV): This measures the average size of red blood cells. An MCV below 80 fL is a strong indicator that someone might be a thalassemia carrier ^[1][2].
• Mean Corpuscular Hemoglobin (MCH): This measures the amount of hemoglobin inside the red blood cells. An MCH below 27 pg is also a sign ^[1][2].

If both the MCV and MCH are normal, the chances of your partner being a standard alpha-thalassemia carrier are low. However, “silent carriers” (who are missing only one alpha-globin gene) can sometimes have normal CBC results. Depending on your partner’s family history or ethnic background, some doctors may still recommend genetic testing.

Step 2: Iron Studies

If the CBC shows that your partner’s red blood cells are smaller than normal (low MCV) or have less hemoglobin (low MCH), the next step is to check their iron levels ^[3]. Doctors often order iron tests at the exact same time as the initial CBC.

Because iron deficiency anemia is very common and causes the exact same changes in red blood cells, it is crucial to rule it out ^[4].

• If iron levels are low, your partner may need iron supplements. The CBC will be repeated after their iron levels return to normal.
• If iron levels are normal, but the MCV and MCH remain low, thalassemia is highly suspected ^[3][4].

Step 3: Hemoglobin Electrophoresis

Alongside the CBC and iron studies, doctors typically order hemoglobin electrophoresis (or Hemoglobin HPLC) ^[3].

While this test is excellent for identifying carriers of beta-thalassemia or sickle cell trait, it is often completely normal in people who carry alpha-thalassemia ^[3][5]. Therefore, a “normal” hemoglobin electrophoresis result does not mean your partner is cleared of being an alpha-thalassemia carrier.

Step 4: DNA Genetic Testing

If your partner has small red blood cells (low MCV/MCH), normal iron levels, and a normal hemoglobin electrophoresis, DNA testing is the required next step ^[3][6].

This is the only definitive way to confirm an alpha-thalassemia diagnosis ^[6]. A laboratory will analyze your partner’s blood sample to look for specific missing or altered alpha-globin genes ^[3][7].

Everyone usually inherits four alpha-globin genes (two from each parent).

• Missing one gene makes you a “silent carrier” with no symptoms.
• Missing two genes makes you a carrier with mild anemia.
• The way the two missing genes are arranged matters significantly. If a person is missing two genes on the same chromosome (known as a ‘cis’ deletion), there is a higher mathematical risk to the baby if their partner is also a carrier ^[8][9].

Knowing the exact genetic mutations for both you and your partner allows a specialist to calculate the exact chances of your baby inheriting a severe condition ^[8]. These conditions include Hemoglobin H disease (which causes moderate to severe anemia requiring medical care) or Alpha-Thalassemia Major (also known as Hb Bart’s Hydrops Fetalis, a condition that is usually fatal for the fetus before or shortly after birth) ^[8][9].

What Are Your Family Planning Options?

If DNA testing confirms that both you and your partner are carriers with a risk of passing on a severe form of alpha-thalassemia, you have empowering family planning options. A genetic counselor can discuss strategies such as:

• In Vitro Fertilization (IVF) with PGT-M: Using IVF to create embryos, and then performing Preimplantation Genetic Testing (PGT-M) to select and transfer only the embryos that do not have the severe disease.
• Prenatal Testing: Becoming pregnant naturally and undergoing early testing, such as Chorionic Villus Sampling (CVS) or Amniocentesis, to check the baby’s genetic status during pregnancy.