Advances in understanding the pathogenesis of familial myeloproliferative neoplasms

Myeloproliferative neoplasms (MPNs) are generally acquired as a result of a somatic stem cell mutation leading to clonal expansion of myeloid precursors. In addition to sporadic cases, familial MPN occurs when one or several MPN affect different relatives of the same family. MPN driver mutations (JAK2, CALR, MPL) are somatically acquired also in familial cases, so a genetic predisposition to acquire one of the MPN driver mutations would be inherited, even though the causative germline mutations underlying familial MPN remain largely unknown. Recently some germline variants [ATG2B and GSKIP duplication, RBBP6 mutations, SH2B3 (LNK) mutations], which can cause familial MPN, have been reported but these mutations are rare and do not explain most familial cases. Patients with familial MPN show the same clinical features and suffer the same complications as those with sporadic disease. This review aims to offer up‐to‐date information regarding the genetics of familial MPN.     

Role of Functional IFNL4, IFNLR1, IFNA,IFNAR2 Polymorphisms in Hepatitis B virus‐related liver disease in Han Chinese population

Recent studies show that variants in some interferon genes together with interferon receptor genes are associated with the outcome of infectious diseases. We examined the association between the risk of hepatitis B virus (HBV)‐related liver disease and the functional polymorphisms within IFNL4, IFNLR1, IFNA1, IFNA2, IFNA5 and IFNAR2 genes (14 loci in all) in a Han Chinese population. A total of 3128 people participated and were divided into 5 groups: healthy controls, natural clearance, chronic hepatitis B(CHB), liver cirrhosis and hepatocellular carcinoma (HCC). Significant associations were observed for 4 variants in IFNAR2, IFNLR1 with HBV infection, and IFNLR1‐rs4649203 was associated with HBV recovery. Moreover, we demonstrated the clear relevance of 5 polymorphisms in IFNA1, IFNA2, IFNL4 with HCC. Three SNPs in IFNL4 gene may be important susceptible factors for the progression of HBV‐related liver disease by trend chi‐square test. The IFNL4 haplotype conformed by rs12971396_G, rs8113007_T and rs7248668A was more frequent in HCC than CHB and LC group. Three polymorphisms in the 5′ region of the IFNL4 gene are associated with the progression of HBV‐related liver disease. IFNA1‐ rs1831583 and IFNA2‐ rs649053 are associated with the development of HCC. IFNLR1‐ rs4649203, rs7525481 are predictors for HBV infection, and rs4649203 is a predictor of spontaneous clearance. IFNAR2 ‐rs1051393, rs12233338 may be predictive markers of HBV infection in the Chinese population.     

Algorithmic evaluation of hereditary erythrocytosis: Pathways and caveats

Multiple algorithms have been published for the evaluation of hereditary erythrocytosis (HE). Typical entry points begin after excluding the more common acquired conditions through investigations of clinical history and assessment of cardiac, pulmonary, or vascular system disorders. Prior exclusion of JAK2 mutations, particularly the common JAK2 V617F mutation, is indicated in adults but less so in pediatric populations. Key decision trees are based on serum erythropoietin levels and p50 results. Recent data reveal some overlap in clinical presentation and laboratory findings in erythrocytosis. Caveats to consider when using algorithmic approaches are discussed.     

ITPA genetic variants influence efficacy of PEG‐IFN/RBV therapy in older patients infected with HCV genotype 1 and favourable IL28B type

Inosine triphosphatase (ITPA) genetic variants are strongly associated with ribavirin (RBV)‐induced anaemia during pegylated interferon (PEG‐IFN) plus RBV therapy. However, the treatment efficacy of ITPA genetic variants has not been fully explored. We enrolled 309 individuals infected with hepatitis C virus genotype 1, who were treated with PEG‐IFN plus RBV for 48 weeks. The ITPA SNP: rs1127354 and IL28B SNP: rs8099917 were genotyped. We examined the risk factors for severe anaemia up to week 12 after the start of treatment and treatment efficacy. The incidence of severe anaemia, ≥3 g/dL reduction or <10 g/dL of haemoglobin (Hb) up to week 12, was more frequent in patients with CC at rs1127354 [65% (145/224), 33% (73/224)] than in those with CA/AA [25% (21/85), 6% (8/85)] (P < 0.0001). ITPA genotype, pretreatment Hb level and age were independent predictive factors for severe anaemia: Hb < 10 g/dL. In IL28B favourable type, the sustained virologic response rate was higher in ≥60‐year‐old patients with CA/AA than in those with CC [71% (22/31) vs 40% (26/65), P = 0.005], although there was no significant difference in treatment efficacy according to ITPA genetic variants in the <60‐year‐old patients. The proportion of patients administered ≥80% of the dosage of RBV was significantly higher in the patients with CA/AA than in those with CC (P = 0.025), resulting in a lower relapse rate. In conclusion, ITPA genetic variants were associated with severe RBV‐induced anaemia and could influence the efficacy of PEG‐IFN plus RBV treatment among elderly patients with IL28B favourable type.     

Role of IFN‐λs,IFN‐λs related genes and the DEPDC5 gene in Hepatitis B virus‐related liver disease

Recent studies have associated genetic variation near the interleukin 28B (IL28B/IFN‐λ3) gene with natural clearance of the hepatitis C virus (HCV) infection, and a common variant in the DEP domain containing 5 (DEPDC5) locus on chromosome 22 has been shown to affect susceptibility to hepatocellular carcinoma (HCC) in Japanese individuals with chronic HCV infection. This study was conducted to determine whether polymorphisms near or in interferon‐lambda (IFN‐λs) genes and their receptor genes such as interleukin 28 receptor, alpha (IL28RA) and interleukin 10 receptor, beta (IL10RB) as well as p21_activated kinases 4 (PAK4) and iron/zinc purple acid phosphatase‐like protein (PAPL), which are locate upstream of IFN‐λs, and lastly the DEPDC5 gene are associated with hepatitis B virus‐related liver disease in Han Chinese. The study subjects included 507 normal healthy controls, 350 individuals with natural clearance of HBV and 792 HBV‐infected patients. The patients were categorized into 157 inactive carriers (Case I), 216 active carriers (Case II), 111 cirrhotics (Case III) and 308 HCC patients (Case IV) subgroups. Seven single nucleotide polymorphisms (SNPs) were genotyped using the Matrix‐assisted Laser Desorption/Ionisation mass spectrometric (MALDI‐TOF MS) SNP genotyping assay. Rs423058 upstream of PAPL, rs2834167 in IL10RB and rs1012068 in DEPDC5 were associated with chronic HBV status, HBV natural clearance and the presence of HCC (P = 0.0004–0.024), respectively. PAPL, IL10RB and DEPDC5 polymorphisms have an impact on progression of HBV‐related liver disease. However, IFN‐λs genes as a tool to differentiate between different clinical courses of HBV infection were not useful in the Han Chinese population.     

Measurements of immature platelets with haematology analysers are of limited value to separate immune thrombocytopenia from bone marrow failure

Detection of immature platelets in the circulation may help to dissect thrombocytopenia due to platelet destruction from bone marrow failure (BMF ). We prospectively tested the predictive value of immature platelets, measured as immature platelet fraction (IPF ) on the XE‐5000 (Sysmex, Kobe, Japan) or percentage of reticulated platelets (rPT ) on the CD Sapphire (Abbott Diagnostics, Santa Clara, CA, USA) to separate immune thrombocytopenia (ITP ) from BMF (leukaemia, myelodysplastic syndrome, aplastic anaemia). We analysed 58 samples of patients with BMF , 47 samples of patients with ITP and 97 controls. Median rPT (CD Sapphire) was increased to 9·0% in ITP and to 10·9% in BMF , compared to 1·9% in controls. Median IPF (XE‐5000) was 16·2% in ITP , 10·2% in BMF and 2·5% in controls. We found an inverse correlation between high fractions of immature platelets and low platelet counts in thrombocytopenic samples regardless of the diagnosis. In conclusion, we observed a broad overlap of immature platelets between ITP and BMF , which may be caused by an accelerated release of immature platelets in any thrombocytopenic state and decreased production in many patients with ITP . Despite this, IPF (XE‐5000) had some power to discriminate ITP from BMF , whereas rPT (CD Sapphire) was of no predictive value.     

Responsiveness of cytogenetically discrete human myeloma cell lines to lenalidomide: lack of correlation with cereblon and interferon regulatory factor 4 expression levels

The introduction of novel immunomodulatory drugs (IMiDs) has dramatically improved the survival of patients with multiple myeloma (MM). While it has been shown that patients with specific cytogenetic subtypes, namely t(4;14), have the best outcomes when treated with bortezomib‐based regimens, the relationship between cytogenetic subtypes and response to IMiDs remains unclear. Using DNA synthesis assays, we investigated the relationship between cytogenetic subtype and lenalidomide response in a representative panel of human myeloma cell lines (HMCLs). We examined HMCL protein expression levels of the lenalidomide target cereblon (CRBN) and its downstream target interferon regulatory factor‐4 (IRF4), which have previously been shown to be predictive of lenalidomide response in HMCLs. Our results reveal that lenalidomide response did not correlate with specific cytogenetic translocations. There were distinct groups of lenalidomide‐responsive and non‐responsive HMCLs, as defined by inhibition of cellular proliferation; notably, all of the hyperdiploid HMCLs fell into the latter category. Repeated dosing of lenalidomide significantly lowered the IC50 of the responsive HMCL ALMC‐1 (IC50 = 2.6 μm vs. 0.005 μm , P < 0.0001), but did not have an effect on the IC50 of the non‐responsive DP‐6 HMCL (P > 0.05). Moreover, no association was found between lenalidomide responsiveness and CRBN and IRF4 expression. Our data indicate that lenalidomide sensitivity is independent of cytogenetic subtype in HMCLs. While CRBN and IRF4 have been shown to be associated with response to lenalidomide in patients, these findings do not translate back to HMCLs, which could be attributable to factors present in the bone marrow microenvironment.     

TLR4/TIRAP polymorphisms are associated with progression and survival of patients with symptomatic myeloma

Myeloma cells thrive in an environment of sustained inflammation, which impacts the development and evolution of the disease, as well as drug resistance. We evaluated the impact of genetic polymorphisms in the Toll‐like receptor 4 (TLR4) pathway, which have been implicated in different inflammatory responses in the outcomes of patients with symptomatic multiple myeloma (MM) who have received contemporary therapies. We found that the presence of single nucleotide polymorphisms (SNPs) in both the TLR4 and toll/interleukin‐1 receptor (TIR)‐associated protein (TIRAP) genes was associated with lower response to primary therapy mainly for patients who received immunomodulatory drugs but not in patients treated with bortezomib‐based therapies. Furthermore, TIRAP SNP was associated with a significantly shorter progression‐free survival and overall survival, independently of other prognostic factors, such as age, transplant, International Staging System stage, lactate dehydrogenase and cytogenetics. This is the first study to demonstrate the effect of SNPs in TLR4/TIRAP in MM. Our data indicate that genetic variability in the immune system may be associated with different responses to antimyeloma therapies and may be a critical component affecting the natural history of the disease, providing the basis for further investigation of the role of these pathways in myeloma.