This page is for you
If your baby was diagnosed with dilated cardiomyopathy and genetic testing found changes in a gene called RPL3L, you are not alone — and the science is moving. This page explains, in plain language, what we know. Your cardiologist and genetic counselor remain your primary medical team; nothing here replaces their advice.
The basics, in plain language
What is a ribosome, and why does it matter for the heart?
Every cell contains thousands of tiny machines called ribosomes that build all of the body's proteins. The heart uses a special version of this machine, built with a protein called RPL3L instead of the usual RPL3 found everywhere else in the body. The heart's version is thought to be fine-tuned for the enormous, lifelong job of pumping blood.
What happens when RPL3L doesn't work?
When a baby inherits two non-working copies of the RPL3L gene — one from each parent — the heart muscle cannot build its special ribosomes properly. The heart muscle weakens and stretches (dilates), so it pumps poorly. This is called dilated cardiomyopathy (DCM), and in babies with RPL3L disease it appears in the first days to weeks of life and can worsen very quickly. Doctors call this disease CMD2D.
How did this happen?
CMD2D is genetic, but it is usually not "passed down" in an obvious way. Parents who carry one changed copy are healthy and usually have no idea. When both parents are carriers, each pregnancy has a 25% (1 in 4) chance of the child having the disease. This is called autosomal recessive inheritance. It is nobody's fault — carriers have no symptoms and no way to know without genetic testing.
Frequently asked questions
How rare is CMD2D?
Very rare. Only about a dozen families worldwide have been reported in the medical literature since 2020. Many experts believe it is under-diagnosed: some babies with neonatal heart failure are never tested for RPL3L. If your family has this diagnosis, you are among the first families known to science — which also means your participation in research is unusually valuable.
What are the signs to watch for?
Babies with CMD2D typically become suddenly unwell in the first month of life: fast breathing, poor feeding, sweating, irritability, pale or bluish skin, and extreme sleepiness. These are emergencies. If a baby with known RPL3L risk shows these signs, go to the emergency department immediately and tell the team about the genetic diagnosis.
How is it treated?
Doctors use heart-failure medicines to support the heart — intravenous medicines in hospital (such as milrinone) and then oral medicines (such as digoxin, diuretics, and blood-pressure medicines). For the most severe cases, heart transplantation is currently the only definitive treatment. At least one reported baby improved substantially on medicines alone over six months, so outcomes can vary — discuss your child's specific situation with their cardiologist.
Can it be cured or prevented?
There is no cure yet. But the underlying biology is unusually promising: scientists know that a related protein, RPL3, can step in for RPL3L when given the chance. Learning how to switch on that backup system is one of the most promising research directions — and one of the reasons this initiative exists.
We already have one affected child. What about future pregnancies?
Once the family's variants are known, parents can pursue genetic counseling about options including prenatal testing and preimplantation genetic testing (testing embryos during IVF). Because one reported case involved a change that arose newly in the child (not present in either parent), targeted testing of both parents is an important first step.
Should siblings or relatives be tested?
Yes — siblings of an affected child have a 25% chance of being affected and a 50% chance of being an unaffected carrier. A genetic counselor can arrange testing. Adult relatives who are carriers are healthy, but they may want to know for family planning.
Does RPL3L affect adults?
People with only one changed copy (carriers) are healthy. Interestingly, large population studies have linked certain RPL3L variants to a somewhat higher risk of an irregular heartbeat called atrial fibrillation in adults. This is an active area of research and something to mention to your doctor if there is a family history.
How can our family help research?
Register your interest through our contact page. With so few known families, every single patient's cells, data, and story can change the field. We will connect you with clinicians and researchers studying RPL3L.
Questions to ask your care team
- Which exact changes (variants) were found in RPL3L, one on each copy?
- Have both parents been tested to confirm carrier status?
- What is the plan if my child's heart function worsens — which transplant center should be involved, and when?
- Is my child eligible for any research study or natural-history registry?
- Should our other children or relatives have genetic testing?
You are not alone
Rare-disease parenting is isolating, but the CMD2D community is small enough that families can know each other by name — and every family's participation measurably moves the science. Reach out via our Get Involved page.