JMML is a complex disorder. We think these key questions and answers form the knowledge building blocks in understanding. The answers are from a parents perspective and are not medical advice. Please ask your medical team to clarify your questions.

The JMML Foundation in the United States provides a helpful set of frequently asked questions together with other helpful JMML facts. Read here

What is a genetic mutation/abnormality?

A genetic mutation is a permanent change in the DNA sequence of a gene. In JMML, mutations have been found in the following genes – PTPN11, K-RAS, N-RAS, CBL and NF1. These mutations may be inherited (germline) or not inherited (somatic).

Currently, the gene in which the mutation occurs influences the treatment approach.

What is a stem cell/bone marrow transplant?

A stem cell transplant is a process where healthy stem cells are extracted from a donor and inserted into a patient. The source of the stem cells can be from the bone marrow of the donor – also referred to as a bone marrow transplant or from the peripheral blood of the donor – stem cell transplant. The stem cells can also be from the umbilical cord of a new born baby.

The process is complex and your medical team will help you navigate through. Bloodwise has a good patient information document on transplants.

What is a “genetic match”?

A genetic match is how close your child’s genetic make up matches that of another person. The degree of match is generally rated on a scale of 6 or 10 with the highest degree of match being 10 on 10 or 6 on 6. You will also hear doctors talk about other variations like 5 on 6 or 9 on 10.

The degree of match influences the treatment approach – the type of drugs used in the pre-conditioning and in managing the take over process. But a genetic match is just one aspect to finding a suitable donor for a transplant.

Be The Match, the National Marrow Donor Program in the United States, explains how genetic matching works. Read more

What is a donor?

A donor is more than a genetic match.  They are contactable, available and in good health.

Generally the first people tested to be donors are your child’s siblings or other relatives children. They may have a high degree of genetic match and they can be immediately contactable, available and in good health.

However, siblings may not have a high enough degree of genetic match. The alternative is to search the global register of stem cell donors. The register currently has 22 million people from around the world on it. The search for a genetic match is quick but the challenge is contacting the person, checking their health and their availability.

Some children may not find a suitable donor on the global register. Fortunately,  organisations like Anthony Nolan and Delete Blood Cancer actively promote stem cell donation and support specific donor drives in communities.

What is a Hickman Line?

A Hickman Line is a long flexible tube inserted into a vein that drains to the heart. Clinicians and Nurses use this lines to give medicine – chemotherapy, take blood for testing, provide nutrition but more importantly give the new stem cells to your child.

The line does require good hygiene practices to prevent infections but the nurses will help you with how to do that.

The Hickman Line or “wigglies” quickly become a part of a parents daily life.

Great Ormond Street Hospital offers more detailed information on central venous devices. Guy’s and St Thomas’ has a helpful document

What is GvHD?

Graft versus host disease (GvHD) is a possible complication after a bone marrow transplant. The donors white blood cells attack the recipient cells. Each situation is unique and again your medical team will help through it.

Cancer Research UK dose provide some more detailed information

Last updated: 19th October 2018