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PubMed This is a summary of 24 peer-reviewed journal articles Updated
Pediatrics · Transient Myeloproliferative Disorder

Why Do Down Syndrome Newborns Need a TMD Blood Test?

At a Glance

Newborns with Down syndrome need a blood test to check for Transient Myeloproliferative Disorder (TMD), a temporary condition where the bone marrow makes too many immature white blood cells. Finding TMD early allows doctors to monitor the child's health and watch for future leukemia risks.

The American Academy of Pediatrics (AAP) recommends that all newborns with Down syndrome receive a Complete Blood Count (CBC) and a peripheral blood smear in the first few days of life [1][2][3]. The primary goal of this routine screening is to check for a temporary blood condition called Transient Myeloproliferative Disorder (TMD), which occurs almost exclusively in babies with Down syndrome [1][4][5].

Hearing the words “blood disorder” or “leukemia risk” in your baby’s first month of life can be terrifying. However, this blood test is a proactive tool. It gives your care team essential baseline information about your baby’s health and ensures that, if your child needs extra monitoring, a plan is in place immediately.

What is Transient Myeloproliferative Disorder (TMD)?

TMD (sometimes called Transient Abnormal Myelopoiesis, or TAM) is a temporary condition where the bone marrow produces too many immature white blood cells, called blasts [1][4]. It happens because the extra copy of chromosome 21 interacts with a specific genetic change (a mutation in the GATA1 gene) that occurs during fetal development [6][7][8].

About 10% of newborns with Down syndrome will develop TMD [1][4]. The condition is unique to infants with Down syndrome (including a rare variation called Trisomy 21 mosaicism) and behaves differently than blood disorders in the general population [6][8].

For the vast majority of babies who have TMD, the condition goes away completely on its own without any treatment, usually within the first three months of life [9][8].

What to Expect from the Blood Test

The initial screening is a standard blood draw. It is usually taken from a tiny vein in your baby’s arm or hand, or sometimes through a heel prick. A CBC looks at the numbers of different blood cells, while a “peripheral blood smear” allows doctors to physically look at the blood cells under a microscope to check for those immature “blast” cells [9][10].

If the doctor sees blast cells on the smear, they will typically run a separate genetic test on the blood sample to look for the GATA1 mutation, which confirms a TMD diagnosis [11][12]. You will usually get the initial CBC results back very quickly (within a day or two), but the genetic confirmation can take a bit longer.

Why the Doctor Checks for It Early

Your doctor needs to do a blood test in the first month because TMD can be “silent.” Many babies with TMD look and act perfectly healthy, showing no outward symptoms [13][9][8]. Without a blood test, the care team would not know the baby had the condition.

When symptoms are present, they can range from mild to severe and may include:

  • An enlarged liver or spleen (detectable when the doctor feels the baby’s belly) [14][15]
  • Unexplained ruddy (reddish) skin, rashes, or small crusted bumps on the skin [16][17][18]
  • Breathing difficulties or signs of fluid buildup [16][19]

If the blood test reveals a very high white blood cell count or if the baby has severe symptoms like liver dysfunction, doctors can intervene early. In these symptomatic cases, doctors will use a short course (often about 7 days) of a low-dose chemotherapy medication called cytarabine [20][21]. While the word “chemotherapy” is scary, this very low dose is highly effective at managing the condition, preventing serious complications, and is generally tolerated far better by newborns with Down syndrome than by older children [20][8][21].

How TMD Relates to Future Leukemia Risk

While TMD typically resolves on its own, doctors pay close attention to it because of what it tells them about the future. Of the babies who have had TMD and recovered, approximately 20% to 30% will go on to develop a specific type of childhood leukemia known as Myeloid Leukemia of Down Syndrome (ML-DS) [9][8][22]. This usually occurs within the first four years of life [9][8].

The initial newborn blood test identifies whether your baby falls into this higher-risk group. If the test detects TMD, your pediatric hematologist will set up a routine schedule to monitor your child’s blood counts over the next few years [23][24].

This monitoring is highly effective. If ML-DS does develop later on, regular blood tests allow the care team to catch it incredibly early. ML-DS is known to be highly treatable, and children with Down syndrome generally respond extremely well to treatment for this specific type of leukemia.

By testing your newborn’s blood in the first few days of life, doctors are removing the guesswork. They are simply identifying whether your baby needs standard pediatric check-ups or if they would benefit from closer hematology monitoring to ensure they stay healthy and thrive.

Common questions in this guide

What is Transient Myeloproliferative Disorder (TMD)?
TMD is a temporary condition in newborns with Down syndrome where the bone marrow produces too many immature white blood cells. For most babies, it goes away completely on its own without any treatment within the first three months of life.
Why does my baby need a blood test if they look healthy?
TMD can be 'silent', meaning your baby might look and act perfectly healthy with no outward signs of illness. A blood test in the first few days of life is the only way to detect the condition and ensure your baby gets the right monitoring plan.
What happens if my newborn's blood test shows TMD?
If the blood smear shows immature cells, doctors usually run a genetic test for the GATA1 mutation to confirm TMD. Your baby's care team will then monitor them closely, and a pediatric hematologist will likely set up a schedule to check their blood counts over the next few years.
What are the symptoms of TMD in infants?
While often symptom-free, TMD can cause an enlarged liver or spleen, reddish skin, unusual rashes, or breathing difficulties. If you notice any of these signs, contact your pediatrician immediately.
Does having TMD mean my child will get leukemia?
Not necessarily, but it does increase the risk. About 20 to 30 percent of babies who recover from TMD develop a highly treatable type of childhood leukemia called ML-DS in their first four years, which is why regular monitoring is so important.

Questions to Ask Your Doctor

Curated prompts to bring to your next appointment.

  1. 1.When will we get the complete results of the initial CBC and peripheral blood smear back?
  2. 2.If blasts are found on the smear, how is the GATA1 mutation testing coordinated, and how long does it take to get those results?
  3. 3.Does our hospital have a pediatric hematologist on staff, or will we be referred to an outside specialist if TMD is suspected?
  4. 4.What specific physical symptoms or changes in my baby should I be watching for at home over the next few weeks?
  5. 5.If my baby's results are clear and show no signs of TMD, what is the ongoing recommended schedule for blood work as they grow?

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References

References (24)
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    Why Is Health Care for Children with Down Syndrome So Crucial from the First Days of Life? A Retrospective Cohort Study Emphasized Transient Abnormal Myelopoiesis (TAM) Syndrome at Three Centers.

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    International journal of environmental research and public health 2022; (19(15)) doi:10.3390/ijerph19159774.

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    Hematological disturbances in Down syndrome: single centre experience of thirteen years and review of the literature.

    Karakurt N, Uslu İ, Aygün C, Albayrak C

    The Turkish journal of pediatrics 2019; (61(5)):664-670.

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    Transient Abnormal Myelopoiesis and AML in Down Syndrome: an Update.

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    Current hematologic malignancy reports 2016; (11(5)):333-41 doi:10.1007/s11899-016-0338-x.

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    Myeloid Proliferations Associated with Down Syndrome: Clinicopathologic Characteristics of Forty Cases from Five Large Academic Institutions.

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This information about newborn TMD screening is for educational purposes only. Always discuss your baby's blood test results and care plan with their pediatrician or pediatric hematologist.

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