MYH9-related disease (MYH9-RD) is a rare autosomal-dominant disorder caused by mutations in the gene for nonmuscle myosin heavy chain IIA (NMMHC-IIA). MYH9-RD is characterized by a considerable variability in clinical evolution: patients present at birth with only thrombocytopenia, but some of them subsequently develop sensorineural deafness, cataract, and/or nephropathy often leading to end-stage renal disease (ESRD). We searched for genotype-phenotype correlations in the largest series of consecutive MYH9-RD patients collected so far (255 cases from 121 families). Association of genotypes with noncongenital features was assessed by a generalized linear regression model. The analysis defined disease evolution associated to seven different MYH9 genotypes that are responsible for 85% of MYH9-RD cases. Mutations hitting residue R702 demonstrated a complete penetrance for early-onset ESRD and deafness. The p.D1424H substitution associated with high risk of developing all the noncongenital manifestations of disease. Mutations hitting a distinct hydrophobic seam in the NMMHC-IIA head domain or substitutions at R1165 associated with high risk of deafness but low risk of nephropathy or cataract. Patients with p.E1841K, p.D1424N, and C-terminal deletions had low risk of noncongenital defects. These findings are essential to patients' clinical management and genetic counseling and are discussed in view of molecular pathogenesis of MYH9-RD.

Key Points Measurement of platelet diameters in 376 patients resulted in a new classification of inherited thrombocytopenias based on platelet size. Measurement of platelet diameters is a useful tool for differential diagnosis of inherited thrombocytopenias.

Inherited thrombocytopenias are heterogeneous diseases caused by at least 20 genes playing different role in the processes of megakaryopoiesis and platelet production. Some forms, such as thrombocytopenia 4 (THC4), are very rare and not well characterized. THC4 is an autosomal dominant mild thrombocytopenia described in only one large family from New Zealand and due to a mutation (G41S) of the somatic isoform of the cytochrome c (CYCS) gene. We report a novel CYCS mutation (Y48H) in patients from an Italian family. Similar to individuals carrying G41S, they have platelets of normal size and morphology, which are only partially reduced in number, but no prolonged bleeding episodes. In order to determine the pathogenetic consequences of Y48H, we studied the effects of the two CYCS mutations in yeast and mouse cellular models. In both cases, we found reduction of respiratory level and increased apoptotic rate, supporting the pathogenetic role of CYCS in thrombocytopenia.

In a group of newly diagnosed acute lymphocytic leukemia (ALL) children we evaluated a number of hemostatic and inflammatory markers at diagnosis and at different time points during chemotherapy for the remission induction to identify alterations in the plasma levels of prothrombotic markers before and during the course of chemotherapy. The following plasma markers were evaluated: thrombin-antithrombin complex (TAT), D-Dimer, plasminogen activator inhibitor 1 (PAI-1), antithrombin, fibrinogen, von Willebrand factor (VWF) antigen and high molecular weight VWF (HMW-VWF) multimers, P-selectin, tumor necrosis factor alpha (TNF-a), and interleukin 6 (IL-6). Plasma samples were collected at the following time points: at T0 (baseline) and T1 (124 days of therapy), T2 (136 days therapy), and T3 (164 days therapy). The results show that, at diagnosis, ALL children presented with laboratory signs of increased thrombin generation and fibrin formation (i.e. high TAT and D-dimer levels), fibrinolysis inhibition (i.e. high PAI-1 level), endothelial activation (i.e., high HMW-VWF and soluble P-selectin levels) and inflammation (i.e. high TNF-alpha and IL-6 levels). After starting induction therapy, the thrombin generation markers and inflammatory cytokines significantly decreased. To the opposite, PAI-1 and P-selectin significantly increased, suggesting an insult by chemotherapy on the vascular endothelium. These effects were more evident during steroid administration. Symptomatic venous thromboembolism (VTE) episodes developed in two cases during induction therapy, which did not allow the evaluation of the predictive value for VTE of laboratory markers. Am. J. Hematol. 85:325-330, 2010. V

Summary We report the long‐term follow‐up (median 39·5 months) of 49 paediatric patients (33 females and 16 males) with refractory symptomatic immune thrombocytopenic purpura (ITP) treated with rituximab. The overall response rate was 69% (34/49 patients). Twenty‐one responders had a platelet count >50 × 109/l at a median 20·2 months from treatment. Kaplan–Meier analysis showed a probability of relapse‐free survival (RFS) of 60% at 36 months from the first rituximab infusion. The number of infusions and a previous splenectomy did not influence overall response rate. Patients who achieved complete response were significantly older at diagnosis and first rituximab infusion than partial responders (P = 0·027). Older children displayed a significantly greater probability of sustained response (RFS) at 36 months than younger children (88·9% vs. 56·7%, P = 0·037). Earlier responses (within 20 d from treatment) were significantly associated with both complete (P = 0·004) and sustained response (P = 0·002). Only mild and transient side‐effects were observed in 9/49 children; no major infections nor delayed toxicities were recorded during the follow‐up.

. The local Ethics Committee approved the protocol. We analyzed data from all the 159 patients admitted in the study period with suspected iron overload based on high TS (above 55% in men and 45% in women) and/or SF (> 322 ng/mL), who had undergone MRI-T2* for heart, liver, spleen, and/or pancreas iron overload and had been screened for the presence of HFE mutations by allele-specific PCR (polymerase chain reaction). The calculations of liver iron concentration (LIC) values were based on liver MRI-T2* measurements, using the Thalassemia-Tools software (Cardiovascular Imaging Solutions, London, UK).Mutations in the HFE gene were identified in 109/159 (68.6%) patients. The most common mutation in our sample was H63D, present in 91 patients (57.2%): 14 (8.8%) were homozygous, 69 (43.4%) heterozygous, and 8 (5%) compound heterozygous for C282Y/H63D. For the C282Y mutation, in contrast, only 5 patients (3.1%) were homozygous and 11 (6.9%) were heterozygous. The S65C mutation was detected in heterozygous state in 2 (2.5%) cases.All 159 patients underwent abdominal MRI-T2* and 126 underwent cardiac MRI-T2* too. Only 3 out of 126 cardiac MRIs had a positive T2* result, mild cardiac overload (T2*: 18.98, 19.14, and 19.8 ms). Of these, two patients had the H63D mutation (1 homozygous and 1 heterozygous) and one patient did not have any of the mutations studied. In the liver, 61 (38.4%) patients had iron overload (T2*: < 11.4 ms and LIC > 2.0 mg/g) of which 57 (35.8%) were light (T2*: 3.83-11.4 ms and LIC: 2.01-6.86 mg/g), and four (2.5%) moderate (T2*: 2.0-3.8 ms and LIC: 7.06-13.56 mg/g). Of these patients with liver overload, 27.9% were C282Y carriers (8.2% homozygous, 11.5% heterozygous, and 8.2% compound heterozygous C282Y/H63D), and 50.8% carried the H63D mutation (14.8% in homozygosis and 36.1% in heterozygosis). Only 12 (19.7%) patients with liver overload did not have the HFE mutation.The presence of C282Y mutation (in either homo or heterozygosis), compound heterozygous (C282/H63D), and H63D in homozygosis was significantly associated with a higher frequency of iron overload in the liver as measured by T2* (P 5 0.001). However, this was not true in patients with H63D in heterozygosis or absence of mutation (P 5 0.42), in which overload frequency was 68.4% and 29.1%, respectively.Pancreatic overload was diagnosed in 33 patients (21%), and 56 patients (35.7%) had splenic overload (Table I). The presence of the C282Y was associated with an overall higher frequency of iron overload. There was also a relatively high frequency (37.3%) of abnormal T2* values in H63D mutants both in the liver and in the spleen, and the frequency of splenic iron overload in H63D mutants was similar to that associated with the C282Y mutation.SF results were available for 152 patients. Median SF was 647 ng/mL (72-13,625), and in 138 patients (90.8%) SF was abnormally high. Overall, in 28 patients (18.2%) serum levels were higher than 1,000 ng/mL, in 80 patients (54%) they varied from 501 to 1,000 ng/mL and in 30 (20.3%) they ranged from 324...

About two-thirds of pediatric patients with PP-IFI survived, regardless of whether the infection occurred after frontline chemotherapy, reinduction chemotherapy for disease relapse, or after HSCT. Further prospective studies are needed to define the impact of antifungal prophylaxis and early combination therapy on short-term overall survival.

SummarySporadic essential thrombocythaemia (ET) is rare in paediatrics, and the diagnostic and clinical approach to paediatric cases cannot be simply copied from experience with adults. Here, we assessed 89 children with a clinical diagnosis of ET and found that 23 patients (25Á8%) had a clonal disease. The JAK2 V617F mutation was identified in 14 children, 1 child had the MPL W515L mutation, and 6 had CALR mutations. The monoclonal X-chromosome inactivation pattern was seen in six patients (two with JAK2 V617F and two with CALR mutations). The other 66 patients (74Á2%) had persistent thrombocytosis with no clonality. There were no clinical or haematological differences between the clonal and non-clonal patients. The relative proportion of ET-specific mutations in the clonal children was much the same as in adults. The higher prevalence of nonclonal cases suggests that some patients may not have myeloproliferative neoplasms, with significant implications for their treatment.