Monitoring the Factory: Bone Marrow Failure and Cancer Risk in SDS

One of the most complex aspects of Shwachman-Diamond Syndrome (SDS) is how it affects the bone marrow over time. While the marrow is responsible for making life-sustaining blood cells, the underlying ribosome problem in SDS puts the marrow under constant stress ^[1]. This stress can lead to two main challenges: the marrow may stop making enough cells (bone marrow failure), or the cells may begin to grow abnormally, leading to Myelodysplastic Syndrome (MDS) or Acute Myeloid Leukemia (AML) ^[2][3].

The Risk of Myeloid Malignancy

For families, the risk of “malignancy” (cancerous changes) is often the most significant concern. It is important to know that a cancer predisposition is not the same as a cancer diagnosis, and most people with SDS do not develop MDS or AML.

However, the risk is elevated. Research from specific registry cohorts and historical eras has shown that between 10% and 17% of individuals with SDS may develop MDS or AML over time ^[1][4].

• Timing: MDS can develop early, with a median age of around 12 years in some groups, while AML is more commonly seen later, often in young adulthood ^[1].
• The “Silent” Shift: A critical fact for parents is that stable blood counts do not rule out evolving disease ^[5]. In one study cohort, a subset of patients who developed MDS (6 of 15 with available data) did so while their routine blood counts (CBCs) appeared stable ^[5][1]. This is why doctors cannot rely on blood draws alone and look directly at the bone marrow through regular biopsies ^[6].

Navigating Somatic Mutations

When doctors look at the marrow, they search for somatic mutations—changes that happen in the marrow cells themselves, not the DNA your child was born with.

• EIF6 Mutations (Somatic Rescue): Some mutations in the EIF6 gene (often found alongside a chromosome change called del(20q)) may act as a somatic rescue ^[7]. They can compensate for the ribosome assembly problem, allowing the marrow to work more efficiently ^[8]. These are generally associated with a lower risk of cancer, though they still require specialist monitoring ^[9].
• TP53 Mutations: Mutations in the TP53 gene are watched more closely. TP53 is a “tumor suppressor” that normally prevents cancer ^[7]. However, a TP53 clone by itself does not automatically mean transplant. A rapidly growing clone or the presence of two TP53 mutations is a high-risk sign that often triggers a discussion about the possibility of a bone marrow transplant ^[10][11].

The Importance of Surveillance

Because MDS and AML can be “silent” in their early stages, regular surveillance is a key strategy for SDS ^[6][12].

• Risk-Adapted Schedule: While many experts recommend an annual full bone marrow evaluation—including morphology (how cells look), cytogenetics (chromosomes), and sometimes molecular sequencing (searching for mutations like TP53)—the schedule is tailored to the individual child by an expert team ^[6].
• Why Surveillance Matters: Patients who undergo regular marrow checks often have better outcomes because the transition to MDS or AML can be caught early ^[5][6].

Early detection allows your medical team to carefully consider interventions (such as beginning the transplant evaluation process) before the disease becomes more difficult to treat ^[12][10]. Your child’s hematologist will use all these pieces of the puzzle—blood counts, marrow looks, and genetic changes—to build a personalized risk profile for your child ^[10]. 🛡️ Individuals who follow a structured surveillance plan give their medical team the best information to guide care if the marrow begins to fail or change.