To decipher the spectrum of variants and phenotype of ACTN1-related thrombocytopenia, we sequenced the ACTN1 gene in 272 cases of unexplained chronic or familial thrombocytopenia.
We concluded that ACTN1-RT is the fourth most frequent form of IT worldwide and it is characterized by platelet macrocytosis in all affected subjects and mild thrombocytopenia in less than 80% of cases.
Moreover, it is worth mentioning data on hypomorphic mutations of FLI1 and the association of single nucleotide polymorphisms, such as that identified in ACTN1, with thrombocytopenia.
Alterations of ACTN1, the gene encoding for α-actinin 1, have recently been identified in a few families as being responsible for a mild form of IT (ACTN1-related thrombocytopenia; ACTN1-RT).
In this issue of Blood, Bottega et al document mutations in ACTN1, which encodes the cytoskeletal protein α-actinin 1, in 10 of 239 consecutive probands with an inherited thrombocytopenia--making ACTN1 an important cause of familial thrombocytopenia.
In the last 5 years, nine new genes whose mutations are responsible for thrombocytopenia have been identified, and this also led to the recognition of several novel nosographic entities, such as thrombocytopenias deriving from mutations in CYCS, TUBB1, FLNA, ITGA2B/ITGB3, ANKRD26 and ACTN1.