Leukocyte Adhesion Deficiency Research Articles

Force-Directed "Mechanointeractome" of Talin-Integrin.

Mechanotransduction from the extracellular matrix into the cell is primarily supervised by a transmembrane receptor, integrin, and a cytosolic protein, talin. Integrin binds ligands on the extracellular side, whereas talin couples integrin receptors to the actin cytoskeleton and later acts as a "force buffer". Talin and integrin together form a mechanosensitive signaling hub that regulates crucial cellular processes and pathways, including cell signaling and formation of focal adhesion complexes, which help cells to sense their mechano-environment and transduce the signal accordingly. Although both proteins function in tandem, most literature focuses on them individually. Here, we provide a focused review of the talin-integrin mechano-interactome network in light of its role in the process of mechanotransduction and its connection to diseases. While working under force, these proteins drive numerous biomolecular interactions and form adhesion complexes, which in turn control many physiological processes such as cell migration; thus, they are invariably associated with several diseases from leukocyte adhesion deficiency to cancer. Gaining insights into their role in the occurrence of these pathological disorders might lead us to establish treatment methods and therapeutic techniques.

A novel mutation of the ITGB2 gene in a Chinese Zhuang minority patient with leukocyte adhesion deficiency type 1 and glucose-6-phosphate dehydrogenase deficiency

ObjectivesTo explore the clinical and molecular characteristics of a Chinese Zhuang minority patient with leukocyte adhesion deficiency type-1 (LAD-1) and glucose-6-phosphate dehydrogenase deficiency (G6PDD). MethodsRoutine clinical and physical examinations were performed, and patient data was collected and analyzed. Protein expression levels of Itgb2 and glucose-6-phosphate dehydrogenase (G6pd) proteins were assessed by flow cytometry and the glucose-6-phosphate (G6P) substrate method, respectively. Whole exome sequencing was performed to investigate genetic variations of the patient and his parents. ResultsThe patient had fester disease and delayed separation of the umbilical cord at birth. Staphylococcus was detected in the fluid secretion of the auditory meatus of the patient. He exhibited a recurrent cheek scab, swollen hand, and swollen gum. Hematological examination indicated dramatic elevation of leukocytes including lymphocytes, monocytes, neutrophils and eosinophils. A novel homozygous mutation was detected in the ITGB2 gene of the patient, which was determined to be a two nucleotide deletion at the site of c.1537–1538 (c.1537–1538delGT), causing a frameshift of 24 amino acids from p.513 and inducing a stop codon (p.V513Lfs*24). A base substitution mutation was identified at c.1466 (c.1466G>T) of G6PD on chromosome X of the patient, which resulted in an amino acid change from arginine to leucine at p.489 (p.R489L). The patient also showed deficient lymphocyte expression of CD18 (2.99%) and significant downregulation of the G6pd protein. ConclusionsThe patient was diagnosed with G6PDD and moderate LAD-1. The combination of LAD-1 and G6PDD in this case may have been due to the high incidence of genetic disease in this minority ethnic population. Analyzing existing LAD-1 and G6PDD cases from different populations can facilitate disease diagnosis and treatment. Particularly, reporting pathogenic mutations of LAD-1 and G6PDD will be crucial for genetic testing and prenatal diagnosis in an effort to decrease the incidence of these diseases.

Leukocyte Adhesion Deficiency Type 1: A Case Series and Review of the Literature

Leukocyte adhesion deficiency type-1 (LAD-1) is a rare primary immunodeficiency that is characterised by compromised neutrophil adhesion and transmigration to infection or inflammation sites. In this article, the authors report the cases of five patients with LAD-1 deficiency. The aim of this study is the demonstration of the wide variety of manifestations in these patients with a review of the literature. Patients were both male and female, with their ages ranging from 1 month to 10 years old. Omphalitis was the most common presentation in this series, followed by pneumonia and gingivitis. Impaired wound healing and cellulitis were other common findings in these patients. Two of the patients did not show delayed separation of the umbilical cord. The findings indicate that LAD-1 remains a life-threatening condition with omphalitis, oral, skin, respiratory tract, and ear infections as the most common complications. Early identification of these patients is essential in ensuring a definitive diagnosis and early implementation of haematopoietic stem cell transplantation.

Carrier frequency of autosomal recessive disorders (BC, BLAD, FXID and CVM) in Holstein cows in Jalisco, Mexico

ABSTRACT: The hereditary autosomal recessive disorders bovine citrullinemia (BC), bovine leukocyte adhesion deficiency (BLAD), factor XI deficiency (FXID), and complex vertebral malformation (CVM) have affected dairy cattle breeding significantly around the world. This study examined the carrier frequency of BC, BLAD, FXID, and CVM autosomal recessive disorders in Bos taurus Holstein cows bred in the Altos Norte region of the state of Jalisco, Mexico. We extracted DNA from 408 random samples of peripheral blood, and then used polymerase chain reaction (PCR) to identify insertion mutations for FXID, and PCR with restriction fragment length polymorphism (PCR-RFLP) for CVM, BC and BLAD. We visualized the PCR products using agarose gel electrophoresis stained with GelRed®. We found that 100% of wild-type (N/N) allele homozygous animals for genes CD18, ASS, and FXI were free of the mutations for BLAD, BC and FXID respectively. For gene SLC35A3 we estimated total carrier frequency of 10.3% and allele frequency of 5%.

Screening of Hardhenu Crossbred, Sahiwal and Hariana Bulls for Autosomal Recessive Genetic Disorder Bovine Leukocyte Adhesion Deficiency (BLAD)

The present study involved screening of Hardhenu crossbred, Sahiwal and Hariana bulls for autosomal recessive genetic disorder i.e Bovine Leukocyte Adhesion Deficiency (BLAD) using PCR based techniques. BLAD is a lethal autosomal recessive disease caused due to a point mutation (A→G) at nucleotide 383 in the CD18 gene which results in substitution of aspartic acid with glycine in the adhesion glycoprotein CD18. All animals under study were maintained at Cattle Breeding Farm, LalaLajpat Rai University of Veterinary and Animal Science (LUVAS), Hisar, India. About 5 ml blood was collected aseptically from jugular vein puncture into EDTA containing tubes, transported to the animal genomics laboratory and stored at-20°C until genomic DNA extraction, which was carried out using Phenol Chloroform method. The targeted genomic area of interest was amplified by using simple PCR technique. The amplified PCR products were digested with TaqI restriction enzyme. The targeted amplicon of 357 bp after digestion of the PCR product, the normal allele in unaffected bull produced two fragments of 201 bp and 156 bp. All the animals under study were found to be free from Bovine Leukocyte Adhesion Deficiency. The molecular screening revealed that none of the bulls screened under study was carrier for BLAD. The present study suggests that the PCR and PCR-RFLP based technique could be employed as an efficient technique for screening of various genetic disorders for identification of carriers or affected animals before using them in breeding programs to minimize the spread of defective allele.

The experience of hematopoietic stem cell transplantation in primary immunodeficiencies in the Russian Children's Clinical Hospital

Primary immunodeficiencies (PID) include a group of congenital diseases, many of which are associated with a high risk of developing life-threatening infectious and non-infectious complications. Many of PIDs require hematopoietic stem cell transplantation (HSCT), which can lead to a complete cure of the disease. The article presents more than 20 years of experience in conducting HSCT with PID in the Russian Children's Clinical Hospital for the period from 1997 to 2018. 88 HSCTs were performed in 80 patients (64 boys and 16 girls) with various PIDs: severe combined immune deficiency (SCID, n = 34), hemophagocytic lymphohistiocytosis (HLH, n = 12), chronic granulomatous disease (CGD, n = 11), Wiskott–Aldrich syndrome (WAS, n = 10), congenital agranulocytosis (n = 4), hyper IgM syndrome type 1 (n = 3), Nijmegen breakage syndrome (n = 2), lymphoproliferative syndrome (n = 2), Chediak–Higashi syndrome (n = 1), leukocyte adhesion deficiency (n = 1). Оverall survival (OS) and event-free survival (EFS) after HSCT with PID was 63.1% and 49.3%. OS after HSCT with SCID was 65.5%, EFS – 48.4%. The article presents the results of HSCT taking into account the type of HSCT, the source of hematopoietic stem cells (HSC) and the type of graft manipulation, conditioning regimen. Growth of positive results of HSCT in patients with PID in recent years is associated with the improvement of accompanying therapy (improving the quality of infection control, the introduction of new drugs for the prevention and treatment of hepatic veno-occlusive disease); technology application TcRα+β+/CD19+ depletion at haploidentical transplantation; optimization of conditioning regimens; successes in the prevention and treatment of the graftversus- host disease (antithymocyte globulin and rituximab administration during the period of conditioning, post-transplant administration of cyclophosphamide at haploidentical HSCT). The study was approved by the Independent Ethics Committee of Russian Children's Clinical Hospital.

CRISPR-Cas9 fusion to dominant-negative 53BP1 enhances HDR and inhibits NHEJ specifically at Cas9 target sites

Precise genome editing/correction of DNA double-strand breaks (DSBs) induced by CRISPR-Cas9 by homology-dependent repair (HDR) is limited by the competing error-prone non-homologous end-joining (NHEJ) DNA repair pathway. Here, we define a safer and efficient system that promotes HDR-based precise genome editing, while reducing NHEJ locally, only at CRISPR-Cas9-induced DSBs. We fused a dominant-negative mutant of 53BP1, DN1S, to Cas9 nucleases, and the resulting Cas9-DN1S fusion proteins significantly block NHEJ events specifically at Cas9 cut sites and improve HDR frequency; HDR frequency reached 86% in K562 cells. Cas9-DN1S protein maintains this effect in different human cell types, including leukocyte adhesion deficiency (LAD) patient-derived immortalized B lymphocytes, where nearly 70% of alleles were repaired by HDR and 7% by NHEJ. Our CRISPR-Cas9-DN1S system is clinically relevant to improve the efficiencies of precise gene correction/insertion, significantly reducing error-prone NHEJ events at the nuclease cleavage site, while avoiding the unwanted effects of global NHEJ inhibition.

Detection of allele and genotype frequencies of bovine leukocyte adhesion deficiency, factor XI deficiency and complex vertebral malformation disease genes in Holstein cattle

Hereditary diseases cause yield and economic loses. It is important to examine hereditary diseases at the molecular level and to remove diseases from the herd. In our study, it was aimed to determine allele frequencies of genes that cause bovine leukocyte adhesion deficiency, factor XI deficiency and complex vertebral malformation diseases in Holstein cattle. Blood samples were randomly taken from 300 Holstein cattle in different dairy farms in Kocaeli, Sakarya and Balıkesir provinces. Deoxyribonucleic acid samples were isolated from blood samples by using the standard ammonium acetate salt-out method. The target regions were amplified by polymerase chain reaction to determine the mutant alleles causing bovine leukocyte adhesion deficiency, factor XI deficiency and complex vertebral malformation. According to the nucleotide chromotograms of the samples subjected to bovine leukocyte adhesion deficiency analysis, it was determined that 4 out of 300 cattle were heterozygous and 296 were homozygous. Polymerase chain reaction procedure for factor XI deficiency disease was sufficient, while samples amplified by polymerase chain reaction for complex vertebral malformation disease were subjected to restriction particle length polymorphism. Factor XI deficiency and complex vertebral malformation disease genes were all homozygous normal.

Efficiency of different fragment lengths of the ubiquitous chromatin opening element HNRPA2B1-CBX3 in driving human CD18 gene expression within self-inactivating lentiviral vectors for gene therapy applications

Patients with leukocyte adhesion deficiency type 1 (LAD1) suffer from life-threatening bacterial infections due to mutations in the common β2 integrin subunit (CD18/ITGB2 gene).We tested different fragments of the ubiquitous chromatin opening element (UCOE) from the human HNRPA2B1-CBX3 locus for their efficiency in driving the human CD18 gene expression and compared it with that of an elongation factor 1 alpha promoter (EF1αL, 1169 bp; EF1αS 248 bp) and a murine stem cell virus (MSCV) promoter within the context of the same lentiviral vector backbone. These vectors were tested in vitro for the human CD18 gene expression on the surface of CD34+ hematopoietic stem cells (HSCs) isolated from both moderate and severe LAD1 patients. Among the promoters tested in the patients' CD34+ HSCs, only U631 bp, U652 bp, U1262 bp, 5′ 2.2 kb A2UCOE and EF1αS resulted in higher percentage of CD18+CD34+ cells comparable to that of the MSCV promoter. The U655 bp, U723 bp, U1296 bp, U2598 bp and EF1αL promoters resulted in comparatively lower numbers of CD18+CD34+ cells. This study would be useful in investigating the human CD18 gene expression in an ex vivo experiment to demonstrate the phenotypic correction of LAD1 in a pre-clinical model.

Adhesive dynamics simulations quantitatively predict effects of kindlin-3 deficiency on T-cell homing.

Leukocyte adhesion is important for the proper functioning of the immune system. While leukocyte homing is mediated by adhesion receptors, the activation of these receptors is modulated by intracellular signaling molecules. In Leukocyte Adhesion Deficiency Type 3, the loss of the kindlin-3 prevents the activation of Leukocyte Function-associated Antigen-1 (LFA-1), which leads to a defect in adhesion, causing recurrent infections and bleeding disorders. Here, we use Integrated Signaling Adhesive Dynamics, a computer model of leukocyte rolling and adhesion combined with a simulated intracellular signaling cascade, to predict the response of T cells to depletion of kindlin-3. Our model predicts that cell adhesion is hypersensitive to the amount of kindlin-3 in the cell, while the rolling velocity is independent of kindlin-3 concentration. In addition, our simulation predicted that the time to stop, an important metric of adhesion, would increase with decreasing kindlin-3 expression. These predictions were confirmed experimentally in experiments using Jurkat cells with reduced expression of kindlin-3. These results suggest that Adhesive Dynamics is a versatile tool for quantifying adhesion in the immune response and predicting the effects of engineering cellular components.

A β2-Integrin/MRTF-A/SRF Pathway Regulates Dendritic Cell Gene Expression, Adhesion, and Traction Force Generation.

β2-integrins are essential for immune system function because they mediate immune cell adhesion and signaling. Consequently, a loss of β2-integrin expression or function causes the immunodeficiency disorders, Leukocyte Adhesion Deficiency (LAD) type I and III. LAD-III is caused by mutations in an important integrin regulator, kindlin-3, but exactly how kindlin-3 regulates leukocyte adhesion has remained incompletely understood. Here we demonstrate that mutation of the kindlin-3 binding site in the β2-integrin (TTT/AAA-β2-integrin knock-in mouse/KI) abolishes activation of the actin-regulated myocardin related transcription factor A/serum response factor (MRTF-A/SRF) signaling pathway in dendritic cells and MRTF-A/SRF-dependent gene expression. We show that Ras homolog gene family, member A (RhoA) activation and filamentous-actin (F-actin) polymerization is abolished in murine TTT/AAA-β2-integrin KI dendritic cells, which leads to a failure of MRTF-A to localize to the cell nucleus to coactivate genes together with SRF. In addition, we show that dendritic cell gene expression, adhesion and integrin-mediated traction forces on ligand coated surfaces is dependent on the MRTF-A/SRF signaling pathway. The participation of β2-integrin and kindlin-3-mediated cell adhesion in the regulation of the ubiquitous MRTF-A/SRF signaling pathway in immune cells may help explain the role of β2-integrin and kindlin-3 in integrin-mediated gene regulation and immune system function.

A Novel Nonsense Mutation in FERMT3 Causes LAD-III in a Pakistani Family.

Leukocyte adhesion deficiency-III (LAD3) is an extremely rare primary immunodeficiency disorder, transmitted with autosomal-recessive inheritance. It is caused by genetic alteration in the FERMT3 gene, which leads to abnormal expression of kindlin-3. This cytoplasmic protein is highly expressed in leukocytes and platelets, and acts as an important regulator of integrin activation. LAD3 has features like bleeding syndrome of Glanzmann-type and leukocyte adhesion deficiency. FERMT3 mutation(s) have not been well characterized in Pakistani patients with LAD3. In this study, an infant and his family of Pakistani origin, presenting with clinical features of LAD, were investigated to determine the underlying genetic defect. Targeted next generation sequencing (TGS) and Sanger sequencing were performed to identify and confirm the causative mutations, respectively, and their segregation within the family. A novel, homozygous FERMT3 nonsense mutation (c.286C > T, p.Q96∗) was found in the proband, and its co-segregation with LAD3 phenotype within the family was consistent with an autosomal recessive inheritance. Both parents were carriers of the same mutation. This family was offered prenatal diagnosis during first trimester of the subsequent pregnancy; the fetus carried the variant. In conclusion, our study is the first report to identify the novel homozygous variant c.286C > T, p.Q96∗in the FERMT3 gene, which might be the causative mutation for LAD3 patients of Pakistani origin.

Proteome Analysis of Human Neutrophil Granulocytes From Patients With Monogenic Disease Using Data-independent Acquisition

Neutrophil granulocytes are critical mediators of innate immunity and tissue regeneration. Rare diseases of neutrophil granulocytes may affect their differentiation and/or functions. However, there are very few validated diagnostic tests assessing the functions of neutrophil granulocytes in these diseases. Here, we set out to probe omics analysis as a novel diagnostic platform for patients with defective differentiation and function of neutrophil granulocytes. We analyzed highly purified neutrophil granulocytes from 68 healthy individuals and 16 patients with rare monogenic diseases. Cells were isolated from fresh venous blood (purity >99%) and used to create a spectral library covering almost 8000 proteins using strong cation exchange fractionation. Patient neutrophil samples were then analyzed by data-independent acquisition proteomics, quantifying 4154 proteins in each sample. Neutrophils with mutations in the neutrophil elastase gene ELANE showed large proteome changes that suggest these mutations may affect maturation of neutrophil granulocytes and initiate misfolded protein response and cellular stress mechanisms. In contrast, only few proteins changed in patients with leukocyte adhesion deficiency (LAD) and chronic granulomatous disease (CGD). Strikingly, neutrophil transcriptome analysis showed no correlation with its proteome. In case of two patients with undetermined genetic causes, proteome analysis guided the targeted genetic diagnostics and uncovered the underlying genomic mutations. Data-independent acquisition proteomics may help to define novel pathomechanisms in neutrophil diseases and provide a clinically useful diagnostic dimension.

Kindlin‐3 recruitment to the plasma membrane in neutrophils precedes high affinity integrin activation

Integrin‐mediated adhesion of circulating leukocytes to the blood vessel wall starts by arrest from rolling. Activation of integrins by inside‐out signaling involves conformational changes from an inactive bent conformation to an extended conformation (E+) with high affinity for ligand binding (H+). The cytoplasmic protein kindlin‐3 is critically required for leukocyte adhesion. Mutations of kindlin‐3 cause leukocyte adhesion deficiency type III (LAD‐III) syndrome, characterized by severe bleeding (a platelet adhesion defect) and recurring infections (a neutrophil adhesion defect). The clinical significance of kindlin‐3 has been extensively studied; however, the molecular mechanism by which kindlin‐3 regulates the β2 integrin activation is unknown. Kindlin‐3 can bind the β2 integrin cytoplasmic tail at a site distinct from the talin‐1 binding site. It remains unclear whether kindlin‐3 affects individual integrin conformation and/or integrin clustering. Here we monitored the spatiotemporal dynamics of kindlin‐3 and β2 integrin conformation changes during neutrophil rolling, arrest and spreading under flow (6 dyn/cm2) using high‐resolution quantitative dynamic footprinting (qDF) microscopy in combination with an integrin conformation‐specific antibody reporting assay and kindlin‐3 fusion reporters. We find that kindlin‐3 is recruited to the plasma membrane during neutrophil adhesion prior to induction of H+ β2 integrin conformation, indicating that kindlin‐3 is required for H+ integrin conformation. Indeed, deletion of kindlin‐3 in neutrophil‐like HL‐60 cells completely abolishes high affinity β2 integrin. Together, our data suggest that kindlin‐3 is permissive for the high affinity β2 integrin conformation.Support or Funding InformationThis work was supported by funding from the National Institutes of Health, USA (NIH, P01‐HL078784).This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Beta2-Integrins and Interacting Proteins in Leukocyte Trafficking, Immune Suppression, and Immunodeficiency Disease.

Beta2-integrins are complex leukocyte-specific adhesion molecules that are essential for leukocyte (e.g., neutrophil, lymphocyte) trafficking, as well as for other immunological processes such as neutrophil phagocytosis and ROS production, and T cell activation. Intriguingly, however, they have also been found to negatively regulate cytokine responses, maturation, and migratory responses in myeloid cells such as macrophages and dendritic cells, revealing new, and unexpected roles of these molecules in immunity. Because of their essential role in leukocyte function, a lack of expression or function of beta2-integrins causes rare immunodeficiency syndromes, Leukocyte adhesion deficiency type I, and type III (LAD-I and LAD-III). LAD-I is caused by reduced or lost expression of beta2-integrins, whilst in LAD-III, beta2-integrins are expressed but dysfunctional because a major integrin cytoplasmic regulator, kindlin-3, is mutated. Interestingly, some LAD-related phenotypes such as periodontitis have recently been shown to be due to an uncontrolled inflammatory response rather than to an uncontrolled infection, as was previously thought. This review will focus on the recent advances concerning the regulation and functions of beta2-integrins in leukocyte trafficking, immune suppression, and immune deficiency disease.

CD11b Regulates Fungal Outgrowth but Not Neutrophil Recruitment in a Mouse Model of Invasive Pulmonary Aspergillosis.

ß2 integrin receptors consist of an alpha subunit (CD11a-CD11d) and CD18 as the common beta subunit, and are differentially expressed by leukocytes. ß2 integrins are required for cell-cell interaction, transendothelial migration, uptake of opsonized pathogens, and cell signaling processes. Functional loss of CD18—termed leukocyte-adhesion deficiency type 1 (LAD1)—results in an immunocompromised state characterized by frequent occurrence of severe infections. In immunosuppressed individuals Aspergillus fumigatus is a frequent cause of invasive pulmonary fungal infection, and often occurs in patients suffering from LAD1. Here, we asked for the importance of CD11b/CD18 also termed MAC-1 which is required for phagocytosis of opsonized A. fumigatus conidia by polymorphonuclear neutrophils (PMN) for control of pulmonary A. fumigatus infection. We show that CD11b−/− mice infected with A. fumigatus were unaffected in long term survival, similar to wild type (WT) mice. However, bronchoalveolar lavage (BAL) performed 1 day after infection revealed a higher lung infiltration of PMN in case of infected CD11b−/− mice than observed for WT mice. BAL derived from infected CD11b−/− mice also contained a higher amount of leukocyte-attracting CCL5 chemokine, but lower amounts of proinflammatory innate cytokines. In accordance, lung tissue of A. fumigatus infected CD11b−/− mice was characterized by lower cellular inflammation, and a higher fungal burden. In agreement, CD11b−/−PMN exerted lower phagocytic activity on serum-opsonized A. fumigatus conidia than WT PMN in vitro. Our study shows that MAC-1 is required for effective clearance of A. fumigatus by infiltrating PMN, and the establishment of an inflammatory microenvironment in infected lung. Enhanced infiltration of CD11b−/− PMN may serve to compensate impaired PMN function.

Macrophage β2-Integrins Regulate IL-22 by ILC3s and Protect from Lethal Citrobacter rodentium-Induced Colitis

SUMMARYβ2-integrins promote neutrophil recruitment to infected tissues and are crucial for host defense. Neutrophil recruitment is defective in leukocyte adhesion deficiency type-1 (LAD1), a condition caused by mutations in the CD18 (β2-integrin) gene. Using a model of Citrobacter rodentium (CR)-induced colitis, we show that CD18−/− mice display increased intestinal damage and systemic bacterial burden, compared to littermate controls, ultimately succumbing to infection. This phenotype is not attributed to defective neutrophil recruitment, as it is shared by CXCR2−/− mice that survive CR infection. CR-infected CD18−/− mice feature prominent upregulation of IL-17 and downregulation of IL-22. Exogenous IL-22 administration, but not endogenous IL-17 neutralization, protects CD18−/− mice from lethal colitis. β2-integrin expression on macrophages is mechanistically linked to Rac1/ROS-mediated induction of noncanonical-NLRP3 (nucleotide-binding domain, leucine-rich-containing family, pyrin domain-containing-3) inflammasome-dependent IL-1β production, which promotes ILC3-derived IL-22. Therefore, β2-integrins are required for protective IL-1β-dependent IL-22 responses in colitis, and the identified mechanism may underlie the association of human LAD1 with colitis.

Leucocyte adhesion deficiency-A multicentre national experience.

Leucocyte adhesion deficiency (LAD) is a rare, innate autosomal recessive immunodeficiency with three subtypes. Twenty-nine patients with LADs were diagnosed and treated in Israeli Medical Centers and in the Palestinian Authority. We discuss the phenotypic, genotypic and biochemical features of LAD-I, LAD-II and LAD-III diagnosed during the neonatal period and early infancy in 18, 6 and 5 patients, respectively. Consanguinity was frequent. Common features were severe infections of variable aetiology, excessive leukocytosis and delayed umbilical cord detachment. In LAD-I, the integrin CD18 expression varied from negligible to normal. However, CD11a expression was negligible in all tested patients, suggesting both CD11a and CD18 should be used to assess this subtype. LAD-II patients showed distinctive facial features, physical malformations, short stature and developmental delay. These patients show defective expression of SLeX (CD15a) on cell surface glycoproteins and lack of H antigen on erythroid cell surfaces resulting in Bombay blood group (hh). LAD-III showed intact but inactive β2 integrins associated with severe infections and significant bleeding disorders caused by defective platelet aggregation and thrombocytopenia. We report four patients with two new unpublished mutations: two LAD-I patients with c.1099delG in ITGB2 and two LAD-III patients with c.1069C>T in FERMT3. LAD-I patients harbouring the c.119_128 deletion in ITGB2 seemed to have better outcomes as compared to other LAD-I patients. Eight patients with LAD-I and -III underwent successful haematopoietic stem cell transplantation. Cumulative survival was 75%, 50% and 40% for LAD-I, LAD-II and LAD-III, with a median follow-up of 4 (0.08-19), 3.25 (1-32) and 6 (0.08-8) years, respectively. Prenatal diagnosis is recommended in families with LAD syndromes.

Genetic Analysis of 13 Iranian Families With Leukocyte Adhesion Deficiency Type 1.

Leukocyte adhesion deficiency type 1 is a rare, autosomal recessive disorder that results from mutations in the ITGB2 gene. This gene encodes the CD18 subunit of β2 integrin leukocyte adhesion cell molecules. Leukocyte adhesion deficiency type 1 is characterized by recurrent bacterial infections, impaired wound healing, inadequate pus formation, and delayed separation of the umbilical cord. Blood samples were taken from 13 patients after written consent had been obtained. Genomic DNA was extracted, and ITGB2 exons and exon-intron boundaries were amplified by polymerase chain reaction. The products were examined by Sanger sequencing. In this study, 8 different previously reported mutations (intron7+1G>A, c.715G>A, c.1777 C>T, c.843del C, c.1768T>C, c.1821C>A, Intron7+1G>A, c.1885G>A) and 2 novel mutations (c.1821C>A; p.Tyr607Ter and c.1822C>T; p.Gln608Ter) were found. c.1821C>A (p.Tyr607Ter) and c.1822C>T (p.Gln608Ter) mutations should be included in the panel of carrier detection and prenatal diagnosis.

A patient with leukocyte adhesion defect

During inflammation, leukocytes play a key role in maintaining tissue homeostasis by elimination of pathogens and removal of damaged tissues. Leukocytes migrate to the site of inflammation by crawling over and through the blood vessel wall, into the tissue. Leukocyte adhesion deficiencies (LAD 1, LAD 2 and LAD 3) are caused by defects in the adhesion of leukocyte to the blood vessel wall due to mutations in the genes encoding b2 integrin, selectin and kindling-3, respectively. Patients experience recurrent none pus forming bacterial infections and neutrophilia, often preceded by delayed separation of umbilical cord. This case report describes a child who presented with umbilical sepsis followed by separation of the umbilical cord on day 15, and recurrent bacterial meningitis with high neutrophilia.