Leukocyte adhesion de ciency type I is rare primary immunode ciency disorder characterized by mutations in the ITGB2 gene encoding CD18. We present clinical and immunological features of 15 patients with leukocyte adhesion de ciency type I (LAD-I). Targeted next-generation sequencing was performed with either a primary immunode ciency gene panel comprising 266 genes or a small LADpanel consisting of ve genes for genetic analysis. To measure the expression level of integrins on the leukocyte surface, ow cytometry analysis was performed. The median age of the patients at diagnosis was 3 (1-48) months. Eleven (73%) of the 15 patients had LAD-I diagnosis in their rst 6 months, and fourteen (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-I were characterized, of which two (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 HSCT. Two of them 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.