A NewATRXMutation in a Patient With Acquiredα-Thalassemia Myelodysplastic Syndrome

The roles of sex and genetics in the MPN

The Philadelphia chromosome negative myeloproliferative neoplasms(MPNs), polycythemia vera (PV), essential thrombocythemia (ET), and primary myelofibrosis (PMF) are acquired hematopoietic stem cell disorders driven by activating mutations of intracellular signal transduction pathways that control the production of circulating blood cells. The MPN are characterized clinically by marked variation in degrees of vascular risk, familial clustering, and evolution to myelofibrosis and acute leukemia. MPN disease presentations and outcomes are highly variable, and are markedly influenced by both sex and germline genetic variation. This chapter will focus on the evidence of sex and germline genetic background as modifiers of MPN development and outcomes. Large population genome wide association studies in both clonal hematopoiesis and MPN have revealed novel mechanisms, including inflammatory pathways and genomic instability, which further our understanding of how sex and genetic background mediate MPN risk. Recent advances in our understanding of clonal hematopoiesis and MPN development in various contexts informs the mechanisms by which sex, inflammation, exposures and genetics influence MPN incidence and outcomes, and provide opportunities to develop new strategies for prognostics and therapeutics in the MPN.

New heritable ATRX mutation identified by whole exome sequencing and review

Background

The mutations in the ATRX gene have been shown to cause two types of disorders: inherited mutations lead to alpha thalassemia X-linked mental retardation (ATR-X) syndrome and acquired somatic mutations cause alpha thalassemia myelodysplastic syndrome (ATMDS). Here we report a case of ATRX gene mutation without completely features of ATR-X or ATMDS syndromes. Moreover we review previous reports of ATRX gene mutations in both ATR-X syndrome and ATMDS.

Methods

After sample collection and DNA extraction, whole exome sequencing was performed using Illumina HiSeq PE150 apparatus. The results were confirmed using Sanger sequencing for the patients and his relatives. Literature review was performed based on the published data in Web of science, Science direct, Springer link and Pubmed databases.

Results

We identified a hemizygous missense ATRX gene mutation (ATRX, c.2388A > C, p. K796N) as a new disease-causing variant in the patient, heterozygous situation for his mother and his father was hemizygous for wild type allele. The literatures of patients were reviewed regarding the ATR-X syndrome.

Conclusions

According to previous findings, inherited ATRX mutations are associated with a broad spectrum of clinical presentations. Therefore a person with a mild α-thalassemia phenotype may also has mutation in ATRX gene. Accordingly, it is critical for geneticist and physicians to increase awareness in molecular diagnosis of α-thalassemia patients.

Incidence of ATRX mutations in myelodysplastic syndromes, the value of microcytosis

Acquired α-thalassemia myelodysplastic syndrome (MDS) (ATMDS) is an acquired syndrome characterized by a somatic point mutation or splicing defect in the ATRX gene in patients with myeloid disorders, primarily MDS. In a large MDS patient series, the incidence of ATMDS was below 0.5%. But no large series has yet assessed the incidence of ATMDS in microcytic MDS. In this study, we focused on patients with MDS and unexplained microcytosis, which was defined as absence of iron deficiency, inflammatory disease, or history of inherited hemoglobinopathy. Our data confirm the low frequency of ATRX mutations in MDS: 0% in an unselected clinical trial cohort of 80 low risk MDS, 0.2-0.8% in a multicenter registry of 2,980 MDS and 43% of MDS with unexplained microcytosis in this same registry. In addition, we reported four novel mutations of the ATRX gene in ATMDS. This study further determines the frequency of ATRX mutations and highlights the importance of microcytosis to detect ATRX mutations within MDS patients.