Familial Predisposition in Myeloproliferative Neoplasms: An NGS-Driven Analysis
Authors: Di Marino Luca , Ramundo Francesco , Malara Tanja , Rossi Monica , Maggi Roberto , Fosso Federica , Betti Silvia , Rossi Elena , Leone Giuseppe , Sica Simona , De Stefano Valerio , Chiusolo Patrizia 
Published: December 2024

Introduction
Myeloproliferative neoplasms (MPNs) are mostly considered neoplasms that arise in adulthood following the acquisition of somatic mutations; however, it is often possible to identify a tendency for clustering of these neoplasms within certain families. To date, except for hereditary forms due to the MPL mutation, no genes are known to be associated with a higher susceptibility to these neoplasms. This study aims to identify germline mutations linked to familial predisposition to MPNs.
Materials and Methods
This monocentric, biological, retrospective study enrolled patients with MPNs who were followed at our center over the past 10 years. A targeted Next Generation Sequencing (NGS) analysis was performed on peripheral blood samples, using a 70-genes panel. Genes are selected based on the available evidence for Hereditary cancer syndromes. Data interpretation was performed using BaseSpace Variant Interpreter and variants were classified into 5 categories based on ACMG guidelines: pathogenic, likely pathogenic, variant of uncertain significance (VUS), likely benign, and benign. Benign and likely benign variants were excluded from our analysis.
Results
We analyzed samples from 54 subjects (32 females, 22 males) affected by myeloid neoplasms (MNs), all of whom had at least one family member also affected by MNs. Twenty-nine subjects (53.7%) had a first-degree relative affected; 22 (40.7%) had a second-degree relative affected; and only 3 (5.6%) had a relative affected at the third degree or higher. Of the 54 subjects, 32 (59.3%) had a family member within the study, providing genomic data for 16 pairs of first-degree relatives.
The most frequent diagnosis was Essential Thrombocythemia (n=25, 49.3%), followed by Polycythemia Vera (20, 37.0%) and Myelofibrosis (5, 9.3%). One subject (1.8%) had unclassifiable MPN and another one (1.8%) had chronic myeloid leukemia (CML). Two (3.7%) subjects had acute myeloid leukemia (AML) and were included as both were siblings of subjects enrolled in the study and affected by MPNs.
JAKV617F was found to be the most common driver mutation (n=39, 72.2%), followed by CALR (n=4, 7.4%) and MPL (n=3, 5.6%). Five (9.3%) subjects were triple-negative, while BCR-ABL was identified in the subject with CML and in one of the subjects with AML, who had also the MPL mutation. The other AML patient had no mutations and in one (1.8%) case driver mutation was not available.
The most frequently mutated genes are ATM (n=8, 14.8%), CHEK2 (n=4, 7.4%), FANCD2 (n=3, 5.6%), ANKRD26 (n=3, 5.6%), APC (n=3, 5.6%), ATG2B (n=3, 5.6%), NF2 (n=2, 3.7%), RET (n=3, 5.6%), TSC2 (n=3, 5.6%), BMPR1A (n=2, 3.7%), PMS2 (n=2,3.7%), RTEL1 (n=4, 7.4%), MECOM (n=3, 5.6%), POLD1 (n=2, 3.7%), and POLE (n=4, 7.4%).
Considering only the 32 patients for whom analysis of both family members was available, the ATM mutation remained the most frequent, present in 6 (11.1%) subjects, with each of the 3 pairs presenting a specific mutation. The ATM mutations identified are Arg2506ThrfsTer3, Gly2508Arg, Arg2719Cys, Leu2492Arg, and Gly3029Asp (1 pathogenic, 1 likely pathogenic, and 3 variants of uncertain significance), all affecting the C-terminal region of the protein where the kinase domain and FAT and FATC portions are located, necessary for the protein's interaction with its ligands and its role in DNA repair.
Conclusions
Our data analysis highlighted the presence of a series of mutations in genes involved in DNA repair, transcription and telomere regulation. In particular, the most frequently mutated gene is ATM, whose germline mutations are known to be associated with the development of various tumors. Our preliminar findings align with recent work by Guijarro1, who identified a germline ATM mutation in 6.4% of subjects diagnosed with AML and MDS, although further data are necessary.
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