SDS & Science Snapshots (2023-02-05)

In this issue: Unusual SDS case report from Uruguay about an adult patient; And, what exactly is a Rare Disease anyway (a project by RDI)?

Welcome to our timely updates on all things SDS, Science, and Advocacy. We bring you a digest of recent scientific publications, conferences, and other newsworthy content - all relevant to SDS - with links to more details and learning opportunities. Are you interested in anything specific? Did we miss something? Let us know. Email connect@SDSAlliance.org or message us on Facebook! This is all for you!

Unusual Shwachman-Diamond Syndrome case report of a 53-year-old woman in Uruguay, diagnosed in her 50s

We have known for a long time that Shwachman-Diamond Syndrome (SDS) presents differently in each patient. While most have blood and pancreatic issues at least intermittently, these hallmark signs are a not reliable tool for diagnosis. Before genetic confirmation became available about 20 years ago, patients were diagnosed based on symptoms alone. And SDS was almost never considered in adult patients, because it was assumed that they would have had obvious symptoms as children already, and because survival was assumed to be very poor. Now, genetic confirmation is routine and is allowing more and more adult patients to be diagnosed. Unfortunately, access to genetic testing is still a challenge, either due to a lack of knowledge or due to economic factors. We are working on both barriers to shorten the diagnostic odyssey for patients everywhere.

In the article we are highlighting this week, access to genetic testing has been a barrier, too. The authors describe the diagnostic journey and symptoms of a woman in her 50s in Uruguay. She has been followed by the clinic for 10 years and had many of the typical SDS symptoms (bone marrow failure with anemia and thrombocytopenia and neutropenia, cryptogenic liver cirrhosis, learning difficulties, short stature, bone issues, and dental problems, etc.), but she also had skin issues that are not typically seen in SDS (unusual skin pigmentation on her face, neck, and extremities; nail abnormalities; premature graying and thin hair). This lead the team to suspect telomeropathies (telomere biology disorders like Dyskeratosis Congenita) and pursued genetic testing specifically for that group of genetic disorders. The results turned out negative

Only later was it possible to pursue genetic testing for SDS using whole exome sequencing as part of a local pilot program aimed at promoting the use of sequencing for the diagnosis of rare genetic diseases. The test found two compound heterozygous mutations in the SBDS gene (the two most common mutations known in SBDS), which lead to the SDS diagnosis.

Unfortunately, the patient passed away in 2021 at the age of 53 years from sepsis due to severe neutropenia. She did not have AML.

“ The patient was followed in a pediatric hospital and referred to the adult hematology clinic which published this case report only at the age of 43 yr. The clinical presentation began during [...] childhood (because she had short stature, learning difficulties, delays in reaching developmental milestones as a child, and a history of cytopenias since childhood). This could have suggested SDS syndrome at that time, but because signs at pediatric age were nonspecific and the genetic tests were not easily available at that time in the country, the diagnosis ended up being very late. It might have been possible that having an early genetic diagnosis would have influenced our patient's outcome. “

We have reached out to the authors to offer assistance in accessing genetic testing, as well as educational and support resources for patients in Uruguay.

Access the article here

Two mutations in the SBDS gene reveal a diagnosis of Shwachman-Diamond syndrome in a patient with atypical symptoms.

Spangenberg MN, Grille S, Simoes C, Dell'Oca N, Boada M, Guillermo C, Raggio V, Spangenberg L. Cold Spring Harb Mol Case Stud. 2022 Dec 28;8(7):a006237. doi: 10.1101/mcs.a006237. Print 2022 Dec. PMID: 36577524

What exactly is Rare Disease, anyway?

Just in time for Rare Disease Day, or rather Rare Disease Month, let’s look at what Rare Disease actually means. Obviously, these are diseases that affect relatively few people. As a consequence, knowledge and treatment options are usually sparse.

To tackle a more clear and more consistent description of the concept of rare disease, the organization Rare Disease International (RDI) partnered with the World Health Organization (WHO) to come to a consensus.

In summary:

A rare disease is a medical condition with a specific pattern of clinical signs, symptoms, and findings that affects fewer than or equal to 1 in 2000 persons living in any World Health Organisation-defined region* of the world. * WHO-defined regions are: Africa, Americas, Eastern Mediterranean, Europe, South-east Asia, Western Pacific
Rare diseases include, but are not limited to, rare genetic diseases, rare cancers, rare infectious diseases, rare poisonings, rare immune-related diseases, rare idiopathic diseases, and rare undetermined conditions.

Talking about numbers….

“While the frequency of most rare diseases can be described by prevalence (the number of cases within a specific population at a given moment or over a specified period), some rare diseases, such as rare cancers and rare infectious diseases, can be more precisely described by incidence (the rate of new cases within a specific population over a particular period).”