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

Defective Treg generation and increased type 3 immune response in leukocyte adhesion deficiency 1

In 15 Turkish LAD-1 patients and controls, we assessed the impact of pathogenic ITGB2 mutations on Th17/Treg differentiation and functions, and innate lymphoid cell (ILC) subsets. The percentage of peripheral blood Treg cells, in vitro-generated induced Tregs differentiated from naive CD4⁺ T cells were decreased despite the elevated absolute counts of CD4⁺ cells in LAD1 patients. Serum IL-23 levels were elevated in LAD1 patients. Post-curdlan stimulation, LAD1 patient-derived PBMCs produced more IL-17A. Additionally, the percentages of CD18-deficient Th17 cells expanded from total or naïve CD4⁺ T cells were higher. The blood ILC3 subset was significantly elevated in LAD1. Finally, LAD1 PBMCs showed defects in trans-well migration and proliferation and were more resistant to apoptosis. Defects in de novo generation of Tregs from CD18-deficient naïve T cells and elevated Th17s, and ILC3s in LAD1 patients' peripheral blood suggest a type 3-skewed immunity and may contribute to LAD1-associated autoimmune symptoms.

Clinical and immunological characteristics of 69 leukocyte adhesion deficiency-I patients

BACKGROUND

In order to support the comprehensive classification of Leukocyte Adhesion Deficiency-I (LAD-I) severity by simultaneous screening of CD11a/CD18, this study assessed clinical, laboratory, and genetic findings along with outcomes of 69 LAD-I patients during the last 15 years.

METHODS

Sixty-nine patients (40 females and 29 males) with a clinical phenotype suspected of LAD-I were referred to Immunology, Asthma, and Allergy research institute, Tehran, Iran between 2007 and 2022 for further advanced immunological screening and genetic evaluations as well as treatment, were enrolled in this study.

RESULTS

The diagnosis median age of the patients was 6 months. Delayed umbilical cord separation was found in 25 patients (36.2%). The median diagnostic delay time was 4 months (min-max: 0-82 months). Forty-six patients (66.7%) were categorized as severe (CD18 and/or CD11a: below 2%); while 23 children (33.3%) were in moderate category (CD18 and/or CD11a: 2%-30%). During the follow-ups, 55.1% of children were alive with a mortality rate of 44.9%. Skin ulcers (75.4%), omphalitis (65.2%), and gingivitis (37.7%) were the most frequent complaints. Genetic analysis of the patients revealed 14 previously reported and three novel pathogenic mutations in the ITGB2 gene. The overall survival of patients with and without hematopoietic stem cell transplantation was 79.3% and 55.6%, respectively.

CONCLUSION

Physicians' awareness of LAD-I considering delayed separation of umbilical cord marked neutrophilic leukocytosis, and variability in CD11 and CD18 expression levels, and genetic analysis leads to early diagnosis and defining disease severity. Moreover, the prenatal diagnosis would benefit families with a history of LAD-I.

Hematologically important mutations: Leukocyte adhesion deficiency (second update)

Leukocyte adhesion deficiency (LAD) is an immunodeficiency caused by defects in the adhesion of leukocytes (especially neutrophils) to the blood vessel wall. As a result, patients with LAD suffer from severe bacterial infections and impaired wound healing, accompanied by neutrophilia. In LAD-I, characterized directly after birth by delayed separation of the umbilical cord, mutations are found in ITGB2, the gene that encodes the β subunit (CD18) of the β₂ integrins. In the rare LAD-II disease, the fucosylation of selectin ligands is disturbed, caused by mutations in SLC35C1, the gene that encodes a GDP-fucose transporter of the Golgi system. LAD-II patients lack the H and Lewis Le^a and Le^b blood group antigens. Finally, in LAD-III, the conformational activation of the hematopoietically expressed β integrins is disturbed, leading to leukocyte and platelet dysfunction. This last syndrome is caused by mutations in FERMT3, encoding the kindlin-3 protein in all blood cells, involved in the regulation of β integrin conformation. This article contains an update of the mutations that we consider to be relevant for the various forms of LAD.

[Leucocyte adhesion deficiency: detection of the first cases in Paraguay]

OBJECTIVE

To implement the diagnostic technique for LAD by evaluating the expression of CD18 and CD15 in healthy patients and in a group with clinical suspicion.

METHODS

Observational, descriptive, and cross-secctional study, carried out in pediatric patients attended in the Instituto de Investigaciones en Ciencias de la Salud, and patients from public hospitals with clinical suspicion of LAD were studied. The molecules CD18 and CD15 in peripheral blood leukocytes was evaluated by flow cytometry, establishing a normal range in healthy patients. The presence of LAD was established by decreased expression of CD18 or CD15.

RESULTS

Sixty pediatric patients were evaluated: 20 apparently healthy and 40 with clinical suspicion of leukocyte adhesion deficiency; 12 of 20 healthy patients were male (median age: 14 years) and 27 of 40 with suspected disease were female (median age: 2 years). Persistent leukocytosis and respiratory tract (32%) infections predominated. The expression range of CD18 and CD15 in healthy patients was 95%-100%, and in patients with clinical suspicion it was 0%-100%. One patient with 0% of CD18 (LAD-1) and one patient with 0% of CD15 (LAD-2) were detecte.

CONCLUSIONS

The implementation of a new diagnostic technique allowed to establish a normal range of CD18 and CD15 by flow cytometry, and it was possible to detect the first two cases of LAD in Paraguay.

Clinical and laboratory findings in patients with leukocyte adhesion deficiency type I: A multicenter study in Turkey

Leukocyte adhesion deficiency type I is a rare primary immunodeficiency disorder characterized by mutations in the ITGB2 gene encoding CD18. We present clinical and immunological features of 15 patients with leukocyte adhesion deficiency type 1 (LAD-1). Targeted next-generation sequencing was performed with either a primary immunodeficiency gene panel comprising 266 genes or a small LAD-panel consisting of five genes for genetic analysis. To measure the expression level of integrins on the leukocyte surface, flow cytometry analysis was performed. The median age of the patients at diagnosis was 3 (1-48) months. Eleven (73%) of the 15 patients had a LAD-1 diagnosis in their first 6 months and 14 (93%) patients had consanguineous parents. Delayed separation of the umbilical cord was present in 80% (n = 12) of the patients in our cohort, whereas omphalitis was observed in 53% (n = 8) of the patients. Leukocytosis with neutrophil predominance was observed in 73% (n = 11) patients. Nine distinct variants in the ITGB2 gene in 13 of the 15 patients with LAD-1 were characterized, two of which (c.305_306delAA and c.779_786dup) are novel homozygous mutations of ITGB2. Four unrelated patients from Syria had a novel c.305_306delAA mutation that might be a founder effect for patients of Syrian origin. Four (27%) patients underwent hematopoietic stem cell transplantation. Two patients died because of HSCT complications and the other two are alive and well. Early differential diagnosis of the patients is critical in the management of the disease and genetic evaluation provides a basis for family studies and genetic counseling.

Clinical and Genetic Spectrum of a Large Cohort of Patients With Leukocyte Adhesion Deficiency Type 1 and 3: A Multicentric Study From India

Leukocyte adhesion deficiency (LAD) syndrome is a group of inborn errors of immunity characterized by a defect in the cascade of the activation and adhesion leading to the failure of leukocyte to migrate to the site of tissue injury. Three different types of LAD have been described. The most common subtype is LAD type 1 (LAD1) caused due to defects in the ITGβ2 gene. LAD type 2 (LAD2) is caused by mutations in the SLC35C1 gene leading to a generalized loss of expression of fucosylated glycans on the cell surface and LAD type 3 (LAD3) is caused by mutations in the FERMT3 gene resulting in platelet function defects along with immunodeficiency. There is a paucity of data available from India on LAD syndromes. The present study is a retrospective analysis of patients with LAD collated from 28 different centers across India. For LAD1, the diagnosis was based on clinical features and flow cytometric expression of CD18 on peripheral blood leukocytes and molecular confirmation by Sanger sequencing. For patients with LAD3 diagnosis was largely based on clinical manifestations and identification of the pathogenic mutation in the FERMT3 gene by next-generation Sequencing. Of the total 132 cases diagnosed with LAD, 127 were LAD1 and 5 were LAD3. The majority of our patients (83%) had CD18 expression less than 2% on neutrophils (LAD1°) and presented within the first three months of life with omphalitis, skin and soft tissue infections, delayed umbilical cord detachment, otitis media, and sepsis. The patients with CD18 expression of more than 30% (LAD1⁺) presented later in life with skin ulcers being the commonest manifestation. Bleeding manifestations were common in patients with LAD3. Persistent neutrophilic leukocytosis was the characteristic finding in all patients. 35 novel mutations were detected in the ITGβ2 gene, and 4 novel mutations were detected in the FERMT3 gene. The study thus presents one of the largest cohorts of patients from India with LAD, focusing on clinical features, immunological characteristics, and molecular spectrum.

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

OBJECTIVES

To 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).

METHODS

Routine 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.

RESULTS

The 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.

CONCLUSIONS

The 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.

Report of a Chinese Cohort with Leukocyte Adhesion Deficiency-I and Four Novel Mutations

PURPOSE

We aimed to report the characteristics of leukocyte adhesion deficiency-I (LAD-I) and four novel mutations in the ITGB2 gene in a Chinese cohort.

METHODS

Seven patients with LAD-I were reported in our study. Clinical manifestations and immunological phenotypes were reviewed. The expression of CD18 was detected by flow cytometry. Next-generation sequencing (NGS) and Sanger sequencing were performed to identify gene mutations.

RESULTS

The mean onset age of all the patients was 1.3 months. Recurrent bacterial infections of the skin and lungs were the most common symptoms. Most patients (6/7) had delayed cord separation. The number of white blood cells (WBC) was increased significantly, except that two patients had a mild increase in the number of WBC during infection-free periods. The expression of CD18 was very low in all patients. Homozygous or compound heterozygous mutations in the ITGB2 gene were identified in each patient. Four mutations were novel, including c.1794dupC (p.N599Qfs*93), c.1788C>A (p.C596X), c.841-849del9, and c.741+1delG. Two patients had large deletions of the ITGB2 gene. Five patients were cured by hematopoietic stem cell transplantation (HSCT).

CONCLUSIONS

This study reported the clinical and molecular characteristics of a Chinese patient cohort. It is helpful in understanding the current status of the disease in China.