Objectives: In this study, we compared the performances of adapted hemophagocytic lymphohistiocytosis (HLH)–2004 guidelines with those of the new diagnostic H-score to identify patients with HLH in a multicenter cohort consisting of adult and pediatric cases of suspected HLH. Methods: The study sample consisted of 147 cases, including 20 adults and 16 children with HLH. Two sets of biological data were evaluated: at presentation and the maximal values reached during the episode. Results: At presentation, for both children and adults, the H-score was more efficient than adapted HLH-2004 guidelines to identify HLH. The diagnostic sensitivity and specificity were respectively 100% and 80% for children and 90% and 79% for adults. However, for adults, performances became comparable between adapted HLH-2004 guidelines and H-score as patient clinical status worsened. The specificity decreased to 73% for the same sensitivity. Conclusions: The adapted HLH-2004 guidelines seem less powerful and H-score seems to be more appropriate for children, which may be due to less significantly marked biological features. For adults, H-score performances are better when determined at presentation. The cutoff value of the H-score should be adapted depending on the target population to obtain optimal specificity.

Significance: Mendelian susceptibility to mycobacterial disease (MSMD) is defined by selective vulnerability to weakly virulent mycobacteria. The 32 known inborn errors of IFN-γ immunity account for MSMD in about half of the patients, and for a smaller proportion of cases of tuberculosis (TB). We report homozygous ZNFX1 variants in two families in which the index cases had MSMD or TB with intermittent monocytosis. Upon overexpression, the two variants encode truncated proteins. We show that human ZNFX1 is localized in ribonucleoprotein granules called stress granules. The patients’ production of and response to IFN-γ are apparently intact, and the patients have not experienced severe viral illnesses. Inherited deficiency of stress granule-associated ZNFX1 is a genetic etiology of MSMD or TB with intermittent monocytosis.

Changes in several components of the clotting system are well documented in sickle cell disease (SCD) patients. However, whether the global hemostatic potential of these patients is altered is still unclear. Calibrated automated thrombogram® method of thrombin generation (TG) was used to characterize the hemostatic potential of 83 SCD children (75 SS, 6 SC, and 2 Sβ ^thal) at steady‐state as compared with 50 controls of the same range of age. TG was triggered using 1 pM tissue factor and 4 μM phospholipids with and without thrombomodulin. Thirteen SCD children were also evaluated during vaso‐occlusive crisis. Protein C activity, free protein S and D‐dimers levels were measured in parallel. SCD patients showed higher rates of thrombin formation, higher thrombin peak height (with and without thrombomodulin), and higher endogenous thrombin potential (ETP) than controls in the presence of thrombomodulin. Reduction of ETP (RETP) in the presence of thrombomodulin was lower in SCD group compared with controls and correlated both with protein C and protein S levels. ETP, RETP, peak height, and velocity index of TG correlated with D‐dimers. Compound heterozygous patients showed an intermediate hemostatic phenotype at steady‐state. No significant difference was observed when comparing TG parameters during vaso‐occlusive crisis to those obtained at steady‐state in the same patients. The global hemostatic potential is increased and reflects the hypercoagulable state of SCD patients even at steady‐state. The relevance of this finding with respect to the risk of thrombotic complications of the disease needs further investigation. Am. J. Hematol. 2011.