Fig. 1

Investigating the molecular mechanisms underlying the reduced penetrance of germline p.Thr354Met mutations observed in a GATA2-mutated MDS/AML family. a Genogram of the GATA2-mutated pedigree. Squares denote males and circles denote females. This five-generation MDS/AML family presented to Barts Health hospital in London with identical germline GATA2 mutations (p.Thr354Met; c.1061C>T) and variable clinical manifestations. Two first-degree cousins (IV.1 and IV.6) presented at 23 and 18 years of age, respectively, with high-grade MDS transforming to AML and monosomy 7. Both cousins died post allogeneic hematopoietic stem cell transplant (HSCT) due to transplant-related complications (IV.1 from graft vs. host disease (GvHD) and IV.6 from relapsed MDS/AML). Ten years later, their first cousin (IV.10) developed symptoms at 31 years, including recurrent minor infections and significant leukopenia (monocytopenia [0.1 × 10⁹/L] and neutropenia [0.8 × 10⁹/L]) with mild macrocytosis and normal hemoglobin and platelet counts. She remains under close surveillance where her blood counts are routinely monitored. All four of her children have inherited her WT GATA2 allele. Similarly, members (IV.7, IV.8, and IV.9) were screened for the mutation and all have a WT GATA2 configuration. The paternal grandmother (II.2) of IV.10 as well as her paternal great-uncle (II.3) and great-grandmother (I.2) all were reported to have died of AML (ages of disease onset were 53, 24, and 53-years old, respectively). Not only did GATA2 mutations correlate with early age of disease onset in the fourth generation (IV.1/23 yr., IV.6/18 yr., and IV.10/31 yr.), but the parental third-generation carriers (III.1, III.5, and III.7) remain hematologically normal and symptom-free into their mid–late 60s. No material was available from other family members. b A clinical timeline of IV.10 showing the change in clinical parameters over the course of disease presentation. Photographs of peripheral blood smears from IV.10 (yr. 1, 3, 4, and 6) stained with May-Grünwald Giemsa staining. Magnification: ×20. c Secondary ASXL1 mutations: variant allele frequencies of GATA2 germline mutation and ASXL1 acquired mutation. Samples from three individuals were sequenced: one asymptomatic parent (III.7), one deceased MDS/AML cousin (IV.6), and across three time-points (yr. 1, 4, and 6) from the symptomatic patient (IV.10) reflecting disease evolution. d GATA2 global expression measured by qRT-PCR of bone marrow samples and normalized to healthy bone marrow control: downregulation in IV.10_yr.1 compared with III.7 and downregulation in IV.10_yr.1–3 GATA2 expression compared with IV.10_yr.4–6. The average of five independent experiments is shown. Statistical significance was determined at *p < 0.05, **p < 0.01, and ***p < 0.001 using a t-test with Bonferroni correction. Error bars represent standard error of the mean (SEM). e GATA2 monoallelic expression of the mutant allele in symptomatic (IV.10) vs. asymptomatic carriers (III.5 and III.7), as measured by cDNA sequencing of bone marrow samples. f Correlation of monoallelic GATA2 expression with disease symptoms across the time-points studied in IV.10 with reactivation of the WT allele “C” expression noted 3 years after presentation, concurrent with improvements in hematological parameters. g RNA-seq analysis: principal component analysis (PCA) plot showing a good separation between GATA2 biallelic (green) and monoallelic (blue) groups based on all transcriptomes