CMMRD (constitutional mismatch repair deficiency syndrome) is a cancer predisposition syndrome that, despite being rare, is very aggressive and penetrant: 90% of affected children will develop a tumor before reaching the age of 20. It is caused by inherited mutations in the genes responsible for correcting DNA pairing errors. The presence of multiple pseudogenes and the identification of variants of unknown significance make genetic diagnosis difficult. At a clinical level, it is also difficult to identify because the range of manifestations is wide and overlaps with other syndromes.
To deal with these challenges, a group led by Drs Gabriel Capellá and Marta Pineda and comprised of IDIBELL, ICO and CIBERONC researchers, has developed and validated the hs-MSI genetic test. By analyzing the errors that accumulate in 192 repetitive regions of the genome called microsatellites, this test determines in a blood sample whether the patient suffers from CMMRD or not. In addition, in their latest publication in the journal Clinical Chemistry, they demonstrate how the test detects microsatellite errors with high sensitivity in all types of tumors caused by the syndrome. This represents a great improvement over traditional tests, which had a sensitivity of 18%. Identifying this feature makes them candidates for immunotherapy, which improves the clinical prognosis of children.
As explained by Dr. Fátima Marín, first author of the article, “with this study we confirm the effectiveness of the hs-MSI test to diagnose CMMRD. We expect the test to be implemented in the ICO Molecular Diagnostics Unit and to be accessible to health professionals”. In addition, Dr Marín indicates that “a national study has been started where this test will be performed on all children with certain types of pediatric cancer with the aim of improving CMMRD detection and thus offer more effective treatments and a better genetic counseling to affected families.”
This study is made possible thanks to funding from the 3Cat La Marató Foundation granted in the 2019 call on rare diseases.
The Bellvitge Biomedical Research Institute (IDIBELL) is a biomedical research center created in 2004. It is participated by the Bellvitge University Hospital and the Viladecans Hospital of the Catalan Institute of Health, the Catalan Institute of Oncology, the University of Barcelona and the City Council of L’Hospitalet de Llobregat.
IDIBELL is a member of the Campus of International Excellence of the University of Barcelona HUBc and is part of the CERCA institution of the Generalitat de Catalunya. In 2009 it became one of the first five Spanish research centers accredited as a health research institute by the Carlos III Health Institute. In addition, it is part of the “HR Excellence in Research” program of the European Union and is a member of EATRIS and REGIC. Since 2018, IDIBELL has been an Accredited Center of the AECC Scientific Foundation (FCAECC).