Validation of Guidelines for Genetic Investigation of Myeloid Neoplasms with Germline Predisposition: Results from a Prospective Cohort Study

Abstract

Purpose: In a multicenter prospective cohort study, we assessed the diagnostic yield of the Nordic guidelines for germline investigation in myeloid neoplasms and mapped the spectrum of inherited and somatic variants.

Experimental design: Eighty-five patients (acute myeloid leukemia, n = 38; myelodysplastic syndromes, n = 26; thrombocytopenia, n = 14; and other, n = 7) fulfilling the Nordic criteria for germline investigation, based on (i) medical history or family history suggestive of a germline condition and (ii) relevant findings from the somatic diagnostic work-up (CytoMol), were recruited. The genetic analysis included enhanced whole-exome sequencing (n = 69) or sequencing of specific variants of interest (n = 16).

Results: Pathogenic or likely pathogenic (P/LP) germline variants were identified in 35% of patients (30/85). The diagnostic yield varied from 6% (1/16) in the family history group to 52% (17/33) in the CytoMol group. Germline DDX41 P/LP variants were the most frequent finding (13/30, 43% of all positive cases) almost exclusively found within the CytoMol group (12/13). Seven variants of unknown significance were also detected (TERT n = 2 and DDX41, RTEL1, ETV6, PARN, and SAMD9 n = 1). Five patients carried a P/LP variant in genes associated with another hereditary cancer syndrome (BRCA1 n = 3; PALB2 n = 1; and CHEK2; n = 1). Survival analysis showed a trend for longer survival among patients with acute myeloid leukemia and confirmed or suspected germline predisposition that underwent allogeneic stem cell transplantation.

Conclusions: The implementation of the Nordic guidelines in a prospective Swedish cohort results in a high overall diagnostic yield (35%), proving the feasibility and utility of these or similar guidelines in a clinical setting.

Figure 1.

Overview of the study cohort. A, Patient enrollment and subcohorts. B, Sankey diagram showing the referral paths of the 85 patients from eight Departments (Dept) of Hematology to five Departments of Clinical Genetics. The number of patients from each department is indicated. CytoMol, inclusion due to findings in the somatic profiling.

Figure 2.

Characteristics of included patients. A, Hematologic disease at inclusion. B, Fulfilled criteria for germline testing. C, Age at inclusion for each inclusion criterion. Individual patients are depicted according to their hematologic disease at diagnosis using different colors and symbols. TP, thrombocytopenia.

Figure 3.

Germline findings in well-established genes for hereditary blood disorders. A, Diagnostic yield in the whole cohort and (B) criterion-based (C) UpSet plot summarizing fulfilled criteria and germline findings. The bar charts on top display the number of patients who fulfilled a single criterion (single filled-in dot below the X-axis) or a combination of criteria (filled-in dots connected by lines below the X-axis). D, Tile plot in which each column represents a unique patient with a germline variant identified. The rows present, from top to bottom, the mutated gene, the main inclusion criteria, the hematologic phenotype at inclusion, and the variant status, P/LP or VUS. Patients GH01_P51 and GH01_P73 carried homozygous variants in DNAJC21 and compound heterozygous variants in SBDS, respectively.

Figure 4.

Clinical characteristics and selected pedigrees. A, Boxplot of age at inclusion for the three diagnostic outcomes with regard to findings in established genes for hereditary blood disorders. “None” refers to patients without any findings. Actual data points are overlaid, their shape illustrating the hematologic phenotype at inclusion. Patients with germline findings in DDX41 genes are presented in red. A Wilcoxon rank-sum test was performed for pairwise comparison of age at inclusion. Adjusted P values are indicated above the boxplot. Ns, not significant. B, Pedigree of three patients belonging to families with inherited thrombocytopenia without hematologic malignancies harboring germline pathogenic variants in ANKRD26 (NM_014915.2). Affected individuals are represented by filled squares (males) and circles (females). The index case is denoted by an arrow. Number or “n” within the symbols represents the known or unknown number of relatives, respectively. P, Pathogenic; TP, thrombocytopenia.

Figure 5.

Survival analysis. A, Kaplan–Meier OS curve for patients with MDS (blue) and AML (red) with available data (not censored for allo-HSCT). B, Kaplan–Meier OS curve for patients with MDS and AML (C) with suspected (MH/FH/S-FH patients without findings) or confirmed germline predisposition compared with patients only fulfilling the CytoMol criteria in which germline predisposition was excluded. D, Kaplan–Meier OS curve for patients with AML with suspected (MH/FH/S-FH patients without findings) or confirmed germline predisposition grouped on whether they received allo-HSCT. E, Kaplan–Meier OS curve for patients with AML grouped on whether they had germline predisposition confirmed through the study and allo-HSCT status. Survival probability on the y-axis and time in months after landmark on the x-axis. Comparison among subgroups was performed using the log-rank test, with the resulting P value presented within the plot.