Siblings and Cord Blood: How Your Baby’s Cord Blood can Help Treat a Sibling | Americord


In New Zealand, a hopeful couple are participating in a study that will use one of their son’s cord blood stem cells to research treatment for another son’s cystic fibrosis. In Chicago, people are using their sibling’s stem cells to successfully treat sickle cell disease. And countless other families have banked their second child’s cord blood after their first child was diagnosed with leukemia. Many of those children are alive and well today thanks to their sibling’s stem cells. Since the first successful cord blood stem cell transplant on a sibling in 1988, over 30,000 cord blood transplants have been performed worldwide.

By banking your newborn’s cord blood, you could be storing a treatment not just for them, but for their siblings.

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On siblings and genetics

We are genetically closest to our siblings. That’s because we inherit half of our DNA from our mother and half from our father, so the genes we inherit are based on a chance combination of our parents’. Our siblings are the only other people inheriting the same DNA.

When a child develops a condition that can be treated with stem cells, they undergo transplant. A doctor infuses stem cells from cord blood or bone marrow into the patient’s bloodstream, where they will turn into cells that fight the disease and repair damaged cells—essentially, they replace and rejuvenate the existing immune system.

Like most transplants, the stem cells must be a genetic match with the patients to be accepted by the body’s immune system. It goes without saying that a patient’s own cord blood will be a 100% match. The second highest chance of a genetic match comes from siblings.

If siblings are a genetic match, a cord blood transplant is a simple procedure that is FDA approved to treat over 80 diseases. However, there are a few considerations you should make before deciding to only bank one of your children’s blood:

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The Advantages of Cord Blood Stem Cells of a Sibling

  • Siblings’ cord blood offers a higher potentil for genetic match.
  • If you choose to bank privately, your child’s cord blood will be available on-demand.

Disadvantages of Cord Blood Stem Cells of a Sibling

  • While the chances of a sibling being a genetic match are higher, the only 100% certain match will be the child’s own cord blood (autologous).
  • The children must be whole siblings for the match to have potential; half-siblings likely will not be a match.

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When can siblings use cord blood?

Stem cells from cord blood can be used for the newborn, their siblings, and potetinally other relatives. Patients with genetic disorders like cystic fibrosis, cannot use their own cord blood and will need stem cells from a sibling’s cord blood. In the case of leukemia or other blood disorders, a child can use either their own cord blood or their sibling’s for treatment.

Here’s a quick guide to which diseases can be treated with a sibling’s cord blood (allogenic), and which can be treated using a child’s own cord blood (autologous):

Disease Allogenic/autologous/both
Leukemias Allogenic
Myelodysplastic syndromes Allogenic
Lymphoma Allogenic
Aplastic anemia Both
Inherited immune system disorders Allogenic
Phagocyte disorders Allogenic
Bone marrow cancers Both
Neuroblastoma Autologous
Clinical trial stages
Autism Autologous
Cerebral Palsy Both
Hearing loss Autologous
MS Autologous
Lupus Both

In the future, scientists believe that cord blood has the potential to treat alzheimer’s, ALS, muscular dystrophy, diabetes, arthritis and many more.

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Can cord blood be used to treat a parent or grandparent?

Generally not. The reason siblings are more likely to match is because they get half of their HLA markers from each parent. Based on the way parents pass on genes, there is a 25 percent chance that two siblings will be a whole match, a 50 percent chance they will be a half match, and a 25 percent chance that they will not be a match at all. It is very rare for a parent to be a match with their own child, and even more rare for a grandparent to be a match.

If I banked privately for one child, do I need to do it for additional children?

You certainly should, especially if you have a family history of any diseases or conditions that could be treated with cord blood stem cells. Since there is only a 25% chance of a match, you should bank the cord blood of each individual child if you have the means.

If a sibling of a child whose cord blood you banked needs a transplant, then your chances of a match will be far higher than turning to the public. However, the safest bet is to bank the cord blood of all your children, safeguarding them against a number of diseases and ensuring a genetic match if necessary.