The study assessed the prevalence of Gaucher disease in Finland and developed methods to screen for potential undiagnosed patients by utilizing point-scoring system developed for Gaucher disease, and data and specimens available in Finnish hospital registers and biobanks. The screening approach established in the study can be adapted to other rare genetic diseases.
Our recent publication on rare diseases (Pehrsson et al., 2022) represents a continuation work of our previously published Gaucher disease studies (Savolainen et al., 2021). The recently published study was carried out by the experts at Takeda Oy, Medaffcon Oy, Helsinki Biobank (HBB), Biobank Borealis of Northern Finland (BB), Helsinki University Hospital, and Helsinki University.
Gaucher disease (GD) is an inherited rare disorder with wide phenotypic spectrum. The symptoms in GD overlap with common conditions, thus further complicating the diagnostic process. It is possible that undiagnosed GD patients exist in Finland. Our biobank studies aimed to develop tools for the screening of potential undiagnosed GD patients from large populations.
The Gaucher Earlier Diagnosis Consensus initiative has previously established a prototype of a GD point-scoring system (GED-C PSS). In our studies, the GED-C PSS was tested in Finnish GD patients. Based on the retrospective assessment of hospital register data, the observed overall GED-C PSS score range in Finnish patients was highly variable, 6.0–22.5 points. More patients and more detailed examinations are needed for the determination of exact clinical threshold values.
The GED-C PSS can also be adapted to automated data mining. Specialized health care recordings of approximately 160,000 Auria biobank subjects were previously GED-C point-scored by automated data mining (Savolainen et al., 2021). While none of the screened biobank sample donors represented previously diagnosed GD patients, a number of subjects with considerably high point scores were identified. However, undiagnosed GD patients were not found in a subsequent biomarker analysis of tested high-score subjects (Savolainen et al., 2021).
In the recently published study, the automated GED-C PSS was used in the screening in conjunction with the unique small nucleotide polymorphism (SNP) chip genotype data from the FinnGen study of Finnish biobank sample donors (Pehrsson et al., 2022). The screening was carried out in a subcohort of HBB population. Up to 45,100 point-scored biobank sample donors also included previously diagnosed GD patients. From the 45,100 subjects, 0.77% had a score of ≥ 10 points. The analysis of the SNP chip genotype data was able to identify the previously diagnosed GD patients, but potential undiagnosed patients were not discovered.
In the recent study, the applicability of paraffin-embedded tissue specimens in the validation of the point-score results by the next-generation sequencing (NGS) of the GD-associated GBA gene was also evaluated. The results obtained on the quality of tissue specimens from HBB and BB were promising , thus highlighting the applicability of tissue specimen collections of the Finnish biobanks in the retrospective studies.
Because undiagnosed GD patients were not found in tested Finnish biobank populations, it is likely that the true prevalence of GD in Finland is close to the prevalence of diagnosed GD patients, ~1:325,000. The SNP chip genotype data available in Finnish biobanks is a valuable addition to the screening approach established in here described Gaucher studies. The approach can be adapted to other rare genetic diseases.
Screening for potential undiagnosed Gaucher disease patients: Utilisation of the Gaucher earlier diagnosis consensus point-scoring system (GED-C PSS) in conjunction with electronic health record data, tissue specimens, and small nucleotide polymorphism (SNP) genotype data available in Finnish biobanks. Pehrsson M, Heikkinen H, Wartivaara-Kautto U, Mäntylahti S, Bäckström P, Lassenius MI, Uusi-Rauva K, Carpén O, Elomaa K. Molecular Genetics and Metabolism Reports (2022)