Shwachman-Diamond syndrome (SDS) is a rare inherited disorder that primarily affects the pancreas, bone marrow, and bones. It is the second most common inherited cause of pancreatic insufficiency after cystic fibrosis, and it carries a significant risk of bone marrow failure and blood cancers over time. Most cases appear in early childhood, when poor growth, digestive problems, and frequent infections prompt further testing.
How SDS Affects the Body
SDS targets three systems simultaneously, which is part of what makes it distinctive. In the pancreas, the cells responsible for producing digestive enzymes are gradually replaced by fat. Without enough of these enzymes, the body struggles to break down and absorb nutrients from food, especially fats. This leads to greasy, foul-smelling stools, poor weight gain, and malnutrition in young children.
The bone marrow, where blood cells are made, also underperforms. Nearly all children with SDS develop neutropenia, meaning they have dangerously low levels of neutrophils, the white blood cells that fight bacterial infections. This is often the earliest blood-related finding and affects 88% to 100% of patients. Anemia shows up in 42% to 82% of cases, and low platelet counts occur in 24% to 88%, sometimes severe enough to cause dangerous bleeding.
Skeletal problems round out the picture. Children with SDS are typically short for their age, and X-rays often reveal abnormal bone development at the growth plates, a pattern called metaphyseal dysostosis. Some children also have rib cage abnormalities, heart defects, hearing loss, or skin conditions resembling eczema.
The Genetic Cause
About 90% of people with SDS carry mutations in a gene called SBDS. This gene helps cells build ribosomes, the tiny molecular machines that assemble proteins. When SBDS doesn’t work properly, cells throughout the body can’t produce proteins efficiently, which is why the syndrome affects multiple organ systems at once. A small number of cases are caused by mutations in related genes (DNAJC21, EFL1, SRP54), all of which also play roles in ribosome assembly. SDS follows an autosomal recessive inheritance pattern, meaning a child must inherit a faulty copy of the gene from each parent.
How SDS Is Diagnosed
A clinical diagnosis requires evidence of both pancreatic insufficiency and bone marrow dysfunction. For the pancreas, doctors look for low levels of specific digestive enzymes in the blood or stool, or imaging that shows the pancreas has been replaced by fat. For bone marrow, the key findings are low blood cell counts on at least two separate occasions or abnormalities seen on a bone marrow biopsy. Genetic testing for SBDS mutations confirms the diagnosis in most cases.
Because the digestive symptoms overlap heavily with cystic fibrosis, distinguishing the two is an important early step. A sweat test typically separates them: children with cystic fibrosis have high sweat chloride levels, while children with SDS have normal results. The underlying mechanisms also differ. In cystic fibrosis, thick secretions block the pancreatic ducts. In SDS, the enzyme-producing cells themselves are replaced by fat, so the ducts aren’t obstructed. Occasionally a sweat test can give a false positive in SDS, so genetic testing may be needed to clarify the picture.
Cancer and Bone Marrow Failure Risk
The most serious long-term concern with SDS is the risk of the bone marrow transforming into a blood cancer. Data from the French registry of 55 SDS patients found that 18.8% developed myelodysplastic syndrome (a pre-leukemia condition) or acute myeloid leukemia by age 20, and that number rose to 36.1% by age 30. This is why regular blood count monitoring and periodic bone marrow evaluations are a core part of lifelong management.
Managing Pancreatic Insufficiency
The digestive problems in SDS are highly treatable. Pancreatic enzyme supplements, taken with meals, replace the enzymes the pancreas can no longer produce. In studies, all patients who received enzyme replacement showed symptom improvement. Children also typically need fat-soluble vitamin supplements (A, D, E, and K) because poor fat absorption means these vitamins aren’t absorbed well either. With consistent enzyme replacement and nutritional support, many children’s digestive symptoms stabilize, though growth may remain below average.
Treating Blood Cell Problems
For the bone marrow side of the disease, treatment depends on severity. When neutropenia is mild or intermittent, careful monitoring and prompt treatment of infections may be enough. For more persistent or severe neutropenia, a medication called G-CSF stimulates the bone marrow to produce more neutrophils. About 64% of patients in one large review received G-CSF, though responses varied. Some saw neutrophil counts rise for just a few weeks, while others stayed on treatment for years.
When the bone marrow fails more broadly, or when there are signs of progression toward leukemia, a stem cell transplant (bone marrow transplant) becomes the consideration. Transplant outcomes depend heavily on timing and the reason for transplant. For patients transplanted because of bone marrow failure alone, five-year survival is around 72%. For those who had already progressed to leukemia or myelodysplastic syndrome before transplant, the outlook is far grimmer: only about 15% survived in one study of 52 transplanted patients, with disease relapse being the primary cause of death. This stark difference underscores why close surveillance matters, as catching marrow changes early gives transplant the best chance of success.
Living With SDS
For patients with slow, stable disease progression, the day-to-day management centers on enzyme supplements, nutritional support, and medications to boost white blood cell counts when needed. Regular blood work and bone marrow checks track for any signs of transformation toward cancer. Many children with SDS attend school, participate in activities, and lead relatively normal daily lives between medical appointments, though they remain more vulnerable to infections than their peers and may need to take extra precautions during illness seasons.
One encouraging aspect of the pancreatic dysfunction is that it sometimes improves with age. Some patients find their enzyme levels gradually rise as they get older, reducing or eliminating the need for supplements. The blood and bone marrow issues, however, require lifelong attention.