Kidd blood group system: outwardly simple with hidden complexity

The basics of the Kidd blood group system have been well described. Two of the three antigens, Jk^a and Jk^b, are polymorphic. The third, Jk3, is of very high prevalence in all populations except in individuals of Polynesian and Finnish extraction. Jk (a?b?) red cells do not express Jk3. The antigens are encoded by SLC14A1 gene on chromosome 18. JK*01 allele differs from JK*02 at nt 838 (G/A) and in the protein, at amino acid 280, Jk^a expression is associated with aspartate and asparagine is associated with Jk^b. The genetic background of the dominantly inherited In(Jk) Jk(a?b?) is due to an 84 bp deletion in ZFN850 on chromosome 19. Antibodies against all three antigens are clinically important. They can cause immediate haemolytic transfusion reactions and are a frequent cause of delayed transfusion reactions. Haemolytic disease of the foetus and newborn due to JK antibodies is generally much less severe than the response to incompatible transfusion. The JK protein on red cells functions as a urea transporter. Complexity in the system is due to the number of alternate alleles described. ISBT recognizes 24 alleles that silence Jk^a/Jk^b expression and 7 alleles causing weak or partial expression of Jk^a or Jk^b. These alleles can result in serological typing discrepancies, discordant serological/molecular results and production of an apparent Kidd alloantibody by an antigen‐positive individual. JK antigens may serve as minor histocompatibility antigens. The antibodies may play a role in renal graft survival when a JK‐incompatible donor kidney is transplanted.     

P1PK: a blood group system with an identity crisis

The P1PK blood group system (ISBT no. 003) was previously called the P blood group system, and the number of included antigens has varied over time. The history of the system is complicated and sometimes confusing, since several changes to the nomenclature have been made. Furthermore, the association between the antigens and their genetic home has raised many questions, as well as the long‐standing enigma regarding the molecular mechanism underlying the common P₁ and P₂ phenotypes. Step by step, the biochemical and genetic basis underlying the antigens expressed in this system has been revealed. This review will start with the historical background and continue with the latest findings, answering some of the questions such as why individuals with p phenotype lack not only P^k and P expression, but also P1, and whether the P1 antigens exist on both glycolipids and glycoproteins on the human red blood cells.     

Cell‐free fetal DNA and fetal blood group genotyping: non‐invasive prenatal testing

In transfusion medicine and clinical immunology, cell‐free fetal DNA (cffDNA) is analysed from maternal plasma of pregnant women to predict fetal blood groups with the purpose of (1) assessing the risk of haemolytic disease of the fetus and newborn (HDFN) in immunized women and (2) guiding targeted Rh prophylaxis in non‐immunized RhD‐negative women. National programmes for guiding prophylaxis are now implemented in around 6–7 European countries; assay accuracy is very high, with sensitivities of 99·9%. Sensitivity is challenged by low quantities of cffDNA, especially in early pregnancy. Specificity is challenged by the polymorphic Rh blood group system, where careful attention is needed to navigate among the many RHD variants that may complicate cffDNA analysis and interpretation of results, especially in populations with mixed ethnicities. However, fetal RHD testing is feasible when implemented with careful attention to these issues. The success of predicting fetal RhD and its successful clinical implementation should encourage widespread implementation. For blood groups that are determined by SNPs, such as KEL or Rhc, novel techniques such as next‐generation sequencing and droplet digital PCR are now providing accurate non‐invasive prediction of these fetal blood groups. Future work on non‐invasive prenatal testing of fetal blood groups determined by SNPs may consolidate the application for cell‐free DNA testing for such targets. At ISBT, the newly formed cfDNA subgroup of the Red Cell Immunogenetics and Blood Group Terminology Working Party will work to facilitate clinical applications, implementation and evaluation of cell‐free DNA testing.     

Clinicopathologic and genetic features of multiple system atrophy with Lewy body disease

Background: Abnormal aggregates of α‐synuclein are pathologic hallmarks of multiple system atrophy (MSA) and Lewy body disease (LBD). LBD sometimes coexists with MSA, but the impact of co‐pathology, particularly diffuse LBD, on presentation of MSA has not been studied. We aimed to determine the frequency and clinicopathologic features of MSA with LBD (MSA+LBD). Methods: Using hematoxylin & eosin and α‐synuclein‐immunostained slides, we assessed the distribution and severity of LBD in 230 autopsy‐confirmed MSA patients collected from 1998 to 2018. Alzheimer‐type pathology was assessed to assign the likelihood of clinical presentations of dementia with Lewy body (DLB) using the consensus criteria for DLB. We reviewed medical records to characterize clinicopathologic features of MSA+LBD. Genetic risk factors for LBD, including APOE ε4 allele and mutations in GBA, SNCA, LRRK2, and VPS35, were analyzed. Results: LBD was observed in 11 MSA patients (5%); seven were brainstem type, three were transitional type, and one was diffuse type. The latter four had an intermediate or high likelihood of DLB. Three of the four had an antemortem diagnosis of Parkinson’s disease with dementia (PDD) or clinically probable DLB. Two patients had neuronal loss in the substantia nigra, but not in striatal or olivocerebellar systems with widespread glial cytoplasmic inclusions, consistent with minimal change MSA. In these cases, LBD was considered the primary pathology, and MSA was considered coincidental. APOE ε4 allele frequency was not different between MSA+LBD and MSA without LBD. Two of nine MSA+LBD patients had a risk variant of GBA (p.T408M and p.E365K). Conclusions: Although rare, MSA with transitional or diffuse LBD can develop clinical features of PDD or DLB. Minimal change MSA can be interpreted as a coincidental, but distinct, α‐synucleinopathy in a subset of patients with diffuse LBD.     

Multiple and bilateral kidney tumors with clear cells of three different histotypes: A case report with clinicopathologic and molecular study

We describe a rare multicentric neoplastic disease arising bilteraly in the kidney. The patient was a 70‐year‐old man, who, during a period of 3 years, was treated for five independent tumors of three histotypes (three multilocular cystic clear cell renal cell neoplasms of low malignant potential, one clear cell renal cell carcinoma, and one clear cell papillary renal cell carcinoma, respectively). Pathologic diagnosis of the reported tumors was confirmed by immunohistochemical analyses, including CD10, CA IX, CK7, AMACR/RACEMASE, and 34 beta E12. Molecular detection of KRAS, BRAF, NRAS, PIK3CA, ALK, ERBB2, DDR2, MAP2K1, RET, and EGFR gene mutational analysis was also performed in all tumors.     

The spectrum of rare central nervous system (CNS) tumors with EWSR1‐non‐ETS fusions: experience from three pediatric institutions with review of the literature

The group of CNS mesenchymal (non‐meningothelial) and primary glial/neuronal tumors in association with EWSR1‐non‐ETS rearrangements comprises a growing spectrum of entities, mostly reported in isolation with incomplete molecular profiling. Archival files from three pediatric institutions were queried for unusual cases of pediatric (≤21 years) CNS EWSR1‐rearranged tumors confirmed by at least one molecular technique. Extra‐axial tumors and cases with a diagnosis of Ewing sarcoma (EWSR1‐ETS family fusions) were excluded. Additional studies, including anchored multiplex‐PCR with next‐generation sequencing and DNA methylation profiling, were performed as needed to determine fusion partner status and brain tumor methylation class, respectively. Five cases (median 17 years) were identified (M:F of 3:2). Location was parenchymal (n = 3) and undetermined (n = 2) with topographic distributions including posterior fossa (n = 1), frontal (n = 1), temporal (n = 1), parietal (n = 1) and occipital (n = 1) lobes. Final designation with fusion findings included desmoplastic small round cell tumor (EWSR1‐WT1; n = 1) and tumors of uncertain histogenesis (EWSR1‐CREM, n = 1; EWSR1‐CREB1, n = 1; EWSR1‐PLAGL1, n = 1; and EWSR1‐PATZ1, n = 1). Tumors showed a wide spectrum of morphology and biologic behavior. For EWSR1‐CREM, EWSR1‐PLAGL1 and EWSR1‐PATZ1 tumors, no significant methylation scores were reached in the known brain tumor classes. Available outcome (4/5) was reported as favorable (n = 2) and unfavorable (n = 2) with a median follow‐up of 30 months. In conclusion, we describe five primary EWSR1‐non‐ETS fused CNS tumors exhibiting morphologic and biologic heterogeneity and we highlight the clinical importance of determining specific fusion partners to improve diagnostic accuracy, treatment and monitoring. Larger prospective clinicopathological and molecular studies are needed to determine the prognostic implications of histotypes, anatomical location, fusion partners, breakpoints and methylation profiles in patients with these rare tumors.     

Refinement and delineation of the breakpoint regions of a chromosome 1;22 translocation in a patient with Costello syndrome*

Altered plasma levels of lipids and lipoproteins, obesity, hypertension, and diabetes are major risk factors for atherosclerotic cardiovascular disease. To identify genes that affect these traits and disorders, we looked for association between markers in candidate genes (apolipoprotein AII (apo AII), apolipoprotein AI‐CIII‐AIV gene cluster (apo AI‐CIII‐AIV), apolipoprotein E (apo E), cholesteryl ester transfer protein (CETP), cholesterol 7α‐hydroxylase (CYP7a), hepatic lipase (HL), and microsomal triglyceride transfer protein (MTP)) and known risk factors (triglycerides (Tg), total cholesterol (TC), apolipoprotein AI (apo AI), apolipoprotein AII (apo AII), apolipoprotein B (apo B), body mass index (BMI), blood pressure (BP), leptin, and fasting blood sugar (FBS) levels.) A total of 1,102 individuals from the Pacific island of Kosrae were genotyped for the following markers: Apo AII/MspI, Apo CIII/SstI, Apo AI/XmnI, Apo E/HhaI, CETP/TaqIB, CYP7a/BsaI, HL/DraI, and MTP/HhpI. After testing for population stratification, family‐based association analysis was carried out. Novel associations found were: 1) the apo AII/MspI with apo AI and BP levels, 2) the CYP7a/BsaI with apo AI and BMI levels. We also confirmed the following associations: 1) the apo AII/MspI with Tg level; 2) the apo CIII/SstI with Tg, TC, and apo B levels; 3) the Apo E/HhaI E2, E3, and E4 alleles with TC, apo AI, and apo B levels; and 4) the CETP/TaqIB with apo AI level. We further confirmed the connection between the apo AII gene and Tg level by a nonparametric linkage analysis. We therefore conclude that many of these candidate genes may play a significant role in susceptibility to heart disease. © 2002 Wiley‐Liss, Inc.     

Kodecytes: modifying the surface of red blood cells

There are few routine techniques available to modify the antigenic surface of red blood cells (RBC). Primarily, modification techniques involve antigen destruction with enzymes or denaturing chemicals. In contrast, very few antigen additive technologies exist. One antigen additive technology involves the passive insertion of Function‐Spacer‐Lipid constructs (Kode Technology) into the cell membrane. Kode constructs can label any cell (creating kodecytes) with controlled levels of almost any small molecule, including blood group carbohydrate and peptide antigens. They have been used to modify RBCs with a variety of ABH, Lewis and related antigens to study the specificity of monoclonal and polyclonal antibodies. Although kodecytes with carbohydrate epitopes have been extensively evaluated, those with peptide antigens also exist and some can be prepared with cross‐reactive bacterially related peptide antigens, to create IgG‐reactive kodecytes. These so‐called ASKGkodecytes can mimic all serological IgG reactions and are particularly suited for teaching and training. Recently kodecytes have also been used to quantify ABH antibody levels without the requirement for plasma dilution, and in this review the probable mechanism of action is explained. In general, kodecytes allow for the controlled antigen modification of RBCs and have the ability to make almost unlimited quantities of antigen rare or unusual RBCs from common resources. Not only are kodecytes useful research tools to study RBCs in vitro and in vivo but they also have the potential to create standardized diagnostics, quality control systems, advanced serological teaching panels and novel research tools.     

Complete remission of VZV reactivation treated with valganciclovir in a patient with total lymphocyte depletion and acute kidney injury after allogeneic bone marrow transplantation

Varicella zoster virus (VZV), a threat for hematopoietic stem cell transplantation (HSCT) recipients, is still one of the most common viral pathogens that affect these patients with a reported incidence ranging between 17% and 50% in the post transplantation period. Valganciclovir (V‐GCV), a valine ester pro‐drug of GCV orally administrable, has recently shown great activity against CMV infections, but there are no reports of its clinical efficacy against VZV. We here report a case history of a patient with positive serologic test for VZV, who underwent allogeneic HSCT and developed an atypical varicella‐like illness. First‐line therapy with foscarnet had to be discontinued due rapid development of renal impairment (creatinine: 2.60 mg/dL, urea: 130.6 mg/dL) and therefore was switched to V‐GCV. The renal impairment and skin lesions of the patient fully recovered after few days of therapy, even though the patient had complete lymphocyte depletion. This is the first case of a patient with chickenpox‐like illness treated successfully with V‐GCV.     

Constitutional LZTR1 mutation presenting with a unilateral vestibular schwannoma in a teenager

Schwannomatosis is a rare neurofibromatosis clinically diagnosed by age‐dependent criteria, with bilateral vestibular schwannoma and/or a constitutional NF2 mutation representing exclusion criteria. Following SMARCB1 germline mutations, constitutional mutations in LZTR1 were discovered. We report on the molecular investigation in a patient presenting at 14 years with a unilateral vestibular schwannoma, ultimately causing blindness and unilateral hearing loss, in the absence of other schwannomas or a positive family history. In DNA derived from frozen tumor tissue, a comprehensive NF2, SMARCB1 and LZTR1 analysis showed an NF2 truncating mutation c.1006_1021delins16; an LZTR1 mutation c.791+1G>A; and a partial 22q deletion including NF2, SMARCB1 and LZTR1. Sequence analysis on peripheral blood derived DNA showed the LZTR1 mutation to be constitutional, but the NF2 mutation and partial 22q deletion were not found, indicating them to be somatic events. RNA‐based targeted analysis confirmed missplicing of LZTR1 intron 8, predicted to result in a premature stop codon. This LZTR1 mutation was paternally inherited. While isolated vestibular schwannoma or NF2 may be considered in a young individual with a unilateral vestibular schwannoma, this report suggests that LZTR1 ‐related schwannomatosis be added to this differential diagnosis.     

Phagocytosis and cytokine response to rough and smooth colony variants of Mycobacterium abscessus by human peripheral blood mononuclear cells

Mycobacterium abscessus is a non‐tuberculous mycobacteria able to cause opportunistic infections in selected patient groups. During the last decades it has emerged as a cause of chronic pulmonary infection in patients with cystic fibrosis (CF). M. abscessus strains exhibit either smooth or rough colony morphology. Strains exhibiting the rough phenotype more often cause pulmonary infections in CF patients than did the smooth ones. Here, we examined phagocytosis and production of cytokines by human peripheral blood mononuclear cells, in response to M. abscessus strains with smooth and rough colony phenotype. The rough isolates all formed multicellular cords, similar to what is observed in Mycobacterium tuberculosis. Monocytes were generally unable to internalize these rough cord isolates, in contrast with the smooth ones. Furthermore, the rough M. abscessus strains induced a distinct cytokine profile differing from that induced by the smooth ones. Rough isolates induced significantly less IL‐10 and tumour necrosis factor compared to smooth strains, but more IL‐1β. Both varieties induced equal amounts of IFN‐γ, IL‐17, IL‐23, IL‐6, IL‐8 and equally little IL‐12. The ability to withstand phagocytosis might be a virulence factor contributing to the capacity of rough M. abscessus strains to give persistent pulmonary infections.     

Maternal red blood cell alloimmunisation Working Party,literature review. RH blood group system: Rare specificities

This report is part of a series reporting the GRADE review performed by the 2018–2020 French Working Party on maternal red blood cell alloimmunisation. This report focusses on the clinical significance in obstetrics, as published in the scientific literature, of the rare RH antibodies, variants and antigens (i.e. excluding conventional RH1 trough RH8 antigens, RH12, RH22 and RH27, which are discussed in other reports of this series). Extremely severe or severe haemolytic disease of the fetus and the newborn (HDFN), leading to death or requiring transfusions, have been reported for: anti-RH1 (-D) associated with DVI, DBT and DIVb phenotypes, RHD*12.04 (DOL4), RHD*03.03 (DIIIc), RHD*D-CE(2-5)-D, RHD*01EL.31 (RHD*148+1T), anti-RH9 (-C^X), anti-RH11 (-E^W), anti-RH17 (-Hr⁰), anti-RH18 (-Hr), anti-RH19 (-hr^S), anti-RH23 (-D^W), anti-RH29 (“total” Rh), anti-RH30 (-Go^a), anti-RH32, anti-RH34 (-Hr^B), anti-RH36 (-Be^a), anti-RH40 (-Tar), anti-RH46 (-Sec), anti-RH48 (-JAL), anti-RH54 (DAK), and antibodies to high prevalence antigens such as those associated with RHCE*02.08.02 (RHCE*C^W-RHD(6-10)), RHCE*03N.01 (RHCE*cEMI). HDFN of moderate, mild or undetailed severity have been reported for: anti-RH1 associated with DHar, DIIIa and DIVa phenotypes, RHD*01EL.08 (RHD*486+1A), RHD*01EL.44 (RHD*D-CE(4-9)-D), RHD*25 (DNB), anti-RH20 (-VS), anti-RH31 (-hr^B), anti-RH37 (-Evans), ani-RH42, anti-RH49 (-STEM), anti-RH51 (-MAR), anti-RH55 (-LOCR), anti-RH58 (-CELO). Positive direct antiglobulin test in the newborn but no clinically significant HDFN has been reported for anti-RH1 (-D) associated with RHD*10.05 (DAU5), RHD*12.02 (DOL2). Because so many specificities are associated with severe HDFN in the RH system, all RH antibodies should be considered as potentially able to cause HDFN, even if none has been reported yet.     

SPINK5 is associated with early‐onset and CHI3L1 with late‐onset atopic dermatitis

We have recently showed that filaggrin (FLG) mutations are associated only with early‐onset of AD, but not with late‐onset of AD. Consequently, other susceptibility genes should receive attention, especially in patients with late‐onset of AD. Our aim was to assess the associations between development of AD and the polymorphisms rs2303067 in SPINK5 and rs490928 in CHI3L1. A study population of 241 AD patients and 164 healthy controls was genotyped for two polymorphisms (rs2303067 in SPINK5 and rs490928 in CHI3L1). Rs2303067 in SPINK5 was significantly associated with early‐onset AD (≤8 years: p = .003; OR = 2.57) and was characterized by the need for hospitalization (p = .006; OR = 2.76), prolonged duration (≥10 years; p = .008; OR = 2.32) and more body parts affected (p = .015; OR = 2.01). In contrast, rs490928 in CHI3L1 was associated with late‐onset AD (>8 years: p = .048; OR = 1.65) and was characterized by no need for hospitalization (p = .049; OR = 1.59), shorter duration (<10 years; p = .017; OR = 1.94) and fewer body parts affected (p = .049; OR = 1.75). Our results confirmed that different AD phenotypes, specifically early‐ and late‐onset AD, have different genetic backgrounds. Early‐onset AD was associated with rs2303067 in SPINK5, which is involved in skin barrier functioning, and late‐onset was associated with rs4950928 in CHI3L1, which is involved in the immune response. Future studies should examine the early‐ versus late‐onset subgrouping more closely.     

Molecular alterations of Ras‐Raf‐mitogen‐activated protein kinase and phosphatidylinositol 3‐kinase‐Akt signaling pathways in colorectal cancers from a tertiary hospital at Kuala Lumpur,Malaysia

Molecular alterations in KRAS, BRAF, PIK3CA, and PTEN have been implicated in designing targeted therapy for colorectal cancer (CRC). The present study aimed to determine the status of these molecular alterations in Malaysian CRCs as such data are not available in the literature. We investigated the mutations of KRAS, BRAF, and PTEN, the gene amplification of PIK3CA, and the protein expression of PTEN and phosphatidylinositol 3‐kinase (PI3K) catalytic subunit (p110α) by direct DNA sequencing, quantitative real‐time PCR, and immunohistochemistry, respectively, in 49 CRC samples. The frequency of KRAS (codons 12, 13, and 61), BRAF (V600E), and PTEN mutations, and PIK3CA amplification was 25.0% (11/44), 2.3% (1/43), 0.0% (0/43), and 76.7% (33/43), respectively. Immunohistochemical staining demonstrated loss of PTEN protein in 54.5% (24/44) of CRCs and no significant difference in PI3K p110α expression between CRCs and the adjacent normal colonic mucosa (p = 0.380). PIK3CA amplification was not associated with PI3K p110α expression level, but associated with male cases (100% of male cases vs 56% of female cases harbored amplified PIK3CA, p = 0.002). PI3K p110α expression was significantly higher (p = 0.041) in poorly/moderately differentiated carcinoma compared with well‐differentiated carcinoma. KRAS mutation, PIK3CA amplification, PTEN loss, and PI3K p110α expression did not correlate with Akt phosphorylation or Ki‐67 expression. KRAS mutation, PIK3CA amplification, and PTEN loss were not mutually exclusive. This is the first report on CRC in Malaysia showing comparable frequency of KRAS mutation and PTEN loss, lower BRAF mutation rate, higher PIK3CA amplification frequency, and rare PTEN mutation, as compared with published reports.     

Cytomegalovirus DNA is highly prevalent in the blood of patients with asthma and is associated with age and asthma traits

Cytomegalovirus (CMV) IgG antibodies have been associated with inflammaging and immunosenescence. We aimed to assess the presence of CMV DNA in the blood of adult and elderly patients with bronchial asthma to establish potential association of CMV DNAemia with asthma and asthma characteristics. Eighty‐five elderly asthmatics, 74 younger asthma patients, and 114 age‐matched controls were recruited. The CMV DNA was detected using commercial artus assay in 10.7% of asthma patients, but was negative in all control individuals. The secondary assay identified CMV DNA in 41.5% of asthmatics and 13.3% of control subjects (P < .001). Presence of CMV DNA was associated with an increased risk of asthma and CMV DNA copy numbers correlated with some asthma traits, including respiratory parameters and exhaled breath nitric oxide. We conclude that CMV infection is associated with asthma and may contribute to the pathogenesis of asthmatic inflammation.     

‘I Can’t Keep Up!’: an update on advances in soft tissue pathology occurring after the publication of the 2020 World Health Organization classification of soft tissue and bone tumours

Progress in our understanding of the pathogenesis and diagnosis of soft tissue neoplasia is exceptionally rapid. Although the most recent World Health Organization classification of soft tissue tumours contains many new entities and refinements of older ones, even this comprehensive document is by now incomplete or in need of modification. This review will attempt to summarise the developments in soft tissue pathology that have occurred since 2020, emphasising lesions for which morphology and genetics intersect in a complementary fashion. Novel entities discussed include KMT2A-rearranged sarcoma, PRRX::NCOAx fibroblastic tumours, EWSR1::PATZ1 sarcomas, BRAF-altered infantile fibrosarcoma-like lesions, NUTM1-rearranged colorectal sarcomas, and a variety of interesting giant cell-rich and matrix-producing lesions. In addition, recently described mimics of atypical lipomatous tumour/well-differentiated liposarcoma are covered, as is a wholly new, morphologically defined and genetically confirmed entity, pseudoendocrine sarcoma. Finally, exciting new developments in the use of immunohistochemistry as a surrogate for molecular genetic techniques are discussed.