Characterization of 11 new cases of leukocyte adhesion deficiency type 1 with seven novel mutations in the ITGB2 gene.
ABSTRACT Leukocyte adhesion deficiency type 1 (LAD I) is an autosomal recessive disorder caused by mutations in the ITGB2 gene, encoding the beta2 integrin family. Severe recurrent infections, impaired wound healing, and periodontal diseases are the main features of disease.
In order to investigate clinical and molecular manifestations of new LAD I cases, 11 patients diagnosed in one center during 7 years were studied. Patients were screened for the ITGB2 gene mutations, using polymerase chain reaction, followed by single-strand conformation polymorphism and sequencing.
The most common first presenting feature of the patients was omphalitis. The mean age of cord separation was 19.9 +/- 1 days. The most common clinical manifestations of the patients during the follow-up period included omphalitis, skin ulcers with poor healing, sepsis, and otitis media. During the follow-up, eight patients died. Eight homozygous changes, including seven novel mutations, were detected: two splicing (IVS4-6C>A, IVS7+1G>A), three missense (Asp128Tyr, Ala239Thr, and Gly716Ala), and three frameshift deletions (Asn282fsX41, Tyr382fsX9, and Lys636fsX22).
Our results indicate that different mutations underlie the development of LAD I. Definitive molecular diagnosis is valuable for genetic counseling and prenatal diagnosis. Regarding clinical presentations, it seems that omphalitis is the most consistent finding seen in LAD I infants.
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ABSTRACT: 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, mutations are found in ITGB2, the gene that encodes the β subunit of the β(2) integrins. This syndrome is characterized directly after birth by delayed separation of the umbilical cord. 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 (also called LAD-I/variant) 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 that is involved in the regulation of β integrin conformation.Blood Cells Molecules and Diseases 11/2011; 48(1):53-61. DOI:10.1016/j.bcmd.2011.10.004 · 2.33 Impact Factor
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ABSTRACT: Leukocyte adhesion deficiency type-I (LAD-I) is caused by mutations in the ITGB2 gene, encoding the β2-subunit of β2-integrin (CD18) which leads to markedly reduced expression of CD18 on leukocytes resulting into recurrent life threatening infections. Here we aim to identify the molecular defects underlying LAD-I in Indian patients and correlate with the clinical presentation. Blood was collected from 30 patients and their parents for absolute neutrophil count, expression of CD18 and CD11 by flow cytometry and DNA extraction. PCR and DNA sequencing of the ITGB2 gene was done for mutation characterization. Phenotypically, 22 patients were LAD-I(0), 1 was LAD-I(-) and 7 were LAD-I(+) showing no expression and reduced expression of CD18 respectively. Nine novel mutations in 15 patients and 11 known mutations in 16 patients were detected. Prenatal diagnosis was performed for 5 families. In this study 30 patients were phenotypically and genotypically evaluated for a less known disease LAD-I. Unavailability of curative options to majority of the patients and high cost of supportive care emphasize the need to increase awareness about a suspicious case so that timely management can be given to the patient and prenatal diagnosis can be offered to their families. Copyright © 2015 Elsevier Inc. All rights reserved.Blood Cells Molecules and Diseases 03/2015; 54(3). DOI:10.1016/j.bcmd.2015.01.012 · 2.33 Impact Factor
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ABSTRACT: Leukocyte adhesion deficiency 1 (LAD-1) is caused by defects in the β2 integrin subunit. We studied 18 missense mutations, 14 of which fail to support the surface expression of the β2 integrins. Integrins with the β2-G150D mutation fail to bind ligands, possibly due to the failure of the α1 segment of the βI domain to assume an α-helical structure. Integrins with the β2-G716A mutation are not maintained in their resting states, and the patient has the severe phenotype of LAD-1. The β2-S453N and β2-P648L mutants support the expression of integrins and adhesion functions. They should be re-classified as polymorphic variants. Copyright © 2014 Elsevier Inc. All rights reserved.Blood Cells Molecules and Diseases 02/2015; 54(2):177-182. DOI:10.1016/j.bcmd.2014.11.005 · 2.33 Impact Factor