Overview
Noonan syndrome-like disorder with juvenile myelomonocytic leukemia (JMML) is a rare condition that combines features of Noonan syndrome with a specific type of childhood blood cancer called juvenile myelomonocytic leukemia. Children with this condition are typically born with physical features similar to Noonan syndrome, such as a distinctive facial appearance (widely spaced eyes, low-set ears, a broad forehead), short stature, heart defects, and sometimes developmental delays. In addition, they develop JMML, a serious blood cancer where the bone marrow makes too many white blood cells called monocytes and myelocytes. These abnormal cells crowd out healthy blood cells, leading to problems like anemia, easy bleeding, enlarged spleen and liver, and frequent infections. This condition is caused by mutations in genes that are part of a signaling pathway called the RAS-MAPK pathway, which controls how cells grow and divide. The most commonly involved gene is CBL, though mutations in KRAS, NRAS, and PTPN11 have also been linked to this disorder. Importantly, in many cases the JMML associated with Noonan syndrome-like features can behave differently from typical JMML — it may sometimes resolve on its own without aggressive treatment, though careful monitoring is essential. Treatment depends on the severity and may range from watchful waiting to chemotherapy or bone marrow transplant in more aggressive cases. Early diagnosis and close follow-up with both genetics and blood cancer specialists are critical for the best outcomes.
Also known as:
Key symptoms:
Distinctive facial features such as widely spaced eyes and low-set earsShort stature or poor growthHeart defects present at birthEnlarged spleenEnlarged liverFrequent or unusual infectionsEasy bruising or bleedingPale skin due to anemiaFatigue and low energySkin rashes or unusual skin findingsDevelopmental delaysFeeding difficulties in infancyExcess white blood cells in the bloodUndescended testicles in boysChest wall abnormalities
Autosomal dominant
Passed on from just one parent; each child has about a 50% chance of inheriting it
Neonatal
Begins at or shortly after birth (first 4 weeks)
Treatments
No FDA-approved treatments are currently listed for Noonan syndrome-like disorder with juvenile myelomonocytic leukemia.
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Specialists
View all specialists →No specialists are currently listed for Noonan syndrome-like disorder with juvenile myelomonocytic leukemia.
Treatment Centers
8 centersBaylor College of Medicine Rare Disease Center ↗
Baylor College of Medicine
📍 Houston, TX
🏥 NORDStanford Medicine Rare Disease Center ↗
Stanford Medicine
📍 Stanford, CA
🔬 UDNNIH Clinical Center Undiagnosed Diseases Program ↗
National Institutes of Health
📍 Bethesda, MD
🔬 UDNUCLA UDN Clinical Site ↗
UCLA Health
📍 Los Angeles, CA
🔬 UDNBaylor College of Medicine UDN Clinical Site ↗
Baylor College of Medicine
📍 Houston, TX
🔬 UDNHarvard/MGH UDN Clinical Site ↗
Massachusetts General Hospital
📍 Boston, MA
🏥 NORDMayo Clinic Center for Individualized Medicine ↗
Mayo Clinic
📍 Rochester, MN
👤 Mayo Clinic Center for Individualized Medicine
🏥 NORDUCLA Rare Disease Day Program ↗
UCLA Health
📍 Los Angeles, CA
Travel Grants
No travel grants are currently matched to Noonan syndrome-like disorder with juvenile myelomonocytic leukemia.
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Caregiver Resources
NORD Caregiver Resources
Support, advocacy, and financial assistance for caregivers of rare disease patients.
Mental Health Support
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Family & Caregiver Grants
Financial assistance programs specifically for caregivers of rare disease patients.
Social Security Disability
Learn how rare disease patients may qualify for SSDI/SSI benefits.
Questions for your doctor
Bring these to your next appointment
- Q1.Which specific gene mutation does my child have, and what does that mean for the likely course of the leukemia?,Is my child's JMML likely to resolve on its own, or will treatment be needed?,How often will my child need blood tests and other monitoring?,Does my child have any heart defects that need treatment or monitoring?,Should other family members be tested for this genetic change?,What developmental support services should we set up for my child?,Are there any clinical trials or new treatments available for this condition?
Common questions about Noonan syndrome-like disorder with juvenile myelomonocytic leukemia
What is Noonan syndrome-like disorder with juvenile myelomonocytic leukemia?
Noonan syndrome-like disorder with juvenile myelomonocytic leukemia (JMML) is a rare condition that combines features of Noonan syndrome with a specific type of childhood blood cancer called juvenile myelomonocytic leukemia. Children with this condition are typically born with physical features similar to Noonan syndrome, such as a distinctive facial appearance (widely spaced eyes, low-set ears, a broad forehead), short stature, heart defects, and sometimes developmental delays. In addition, they develop JMML, a serious blood cancer where the bone marrow makes too many white blood cells called
How is Noonan syndrome-like disorder with juvenile myelomonocytic leukemia inherited?
Noonan syndrome-like disorder with juvenile myelomonocytic leukemia follows a autosomal dominant inheritance pattern. Genetic counseling can help families understand recurrence risk and testing options.
At what age does Noonan syndrome-like disorder with juvenile myelomonocytic leukemia typically begin?
Typical onset of Noonan syndrome-like disorder with juvenile myelomonocytic leukemia is neonatal. Age of onset can vary across affected individuals.