Doubled genes cause bone marrow trouble

The genetic change causing an inherited form of a bone marrow disorder linked to leukaemia, myeloproliferative neoplasm (MPN), has been identified by a team of scientists from several French research institutes. 

The team included Emna Mahfoudhi, who is also affiliated with the Institut Pasteur de Tunis.

The researchers investigated two families from the French West Indies with inherited MPN. They identified a region of chromosome 14 linked with MPN, but sequencing it revealed no mutations associated with the disease. Instead, they discovered a duplicated stretch of DNA in the MPN patients. 

Two of the duplicated genes, ATG2B and GSKIP, were more strongly expressed in patients, making them more sensitive to the signalling proteins that control blood cell production. 

In addition to its direct effects, the duplication also cooperates with MPN-associated mutations. It improves the fitness of cells with a mutant allele of the signalling gene JAK2, enabling them to spread and leading to increased blood cell formation.

The team confirmed the duplication in two other French West Indies families with similar MPN symptoms, but it was absent in Eurocaucasian MPN patients. The duplication may only be linked to particular kinds of MPN; however, it's also possible that genetic defects in other populations are limited to ATG2B and GSKIP. 

“These genes should be studied in large cohorts to find out if they are mutated or duplicated in the genome,” says Isabelle Plo, one of the lead authors, adding that the two genes may serve as therapeutic targets.

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