To the Editor: We read with much interest the article by Ferri et al (1) published in the June 2012 issue of JPGN. They had reported interesting original personal and international (Brazil, Egypt, Germany, Israel, United Kingdom, and Turkey) literature data on the presence of thrombophilia in children with the diagnosis of portal vein thrombosis (PVT) without liver disease. As correctly pointed out by them, studies on old and novel thrombophilic risk factors in pediatric PVT are still fragmentary, and sometimes controversial or unexpected. In this regard, the authors had particularly underlined the possible role played by ethnic/geographical variations, and the surprisingly apparent lack of involvement of Janus kinase 2 (JAK2-VS17). This is a novel mutated protein kinase protagonist in adult series of splanchnic venous thrombosis and/or myeloproliferative disorders (2), which has still been seldom investigated in pediatric population. The authors had concluded that even after investigation of hereditary and acquired thrombophilia, PVT remains without a defined cause in the majority of the evaluated patients. We believe that this conclusion may be useful to the journal readership, urging them to also focus on a recent study of our group on genetic risk factors in 19 similar cases of Italian origin with PVT (3). We also did not find the JACK2-VS17 mutation in any of the studied patients. In our own series, among 12 of 19 patients (63%) with neonatal history of umbilical vein catheterization, a genetic variant (factor V Leyden, n = 1; prothrombin G20210A mutation, n = 2) tended to be more frequent (ie, 25%) than in the remaining 7 of 19 of the idiopathic group (factor V Leyden, n = 1; 14.3%). We believe that the data from the study by Ferri et al (1), along with those quoted in their references, and our personal results as well (3), call for a meta-analytical study of literature evidences and prospective larger studies, assessing these and also other thrombophilic markers, to gain a better insight into the mechanisms underlying pediatric PVT. This information will possibly be useful for better establishment of the real need for timely prophylactic anticoagulation strategies when indicated.