Case Report: Compound heterozygous ITGB2 variants causing leukocyte adhesion deficiency type I With preserved CD18 expression.

UNLABELLED: Introduction Leukocyte adhesion deficiency (LAD) type I is a well-recognized inborn error of immunity that typically presents in early childhood. However, cases with normal surface expression of adhesion molecules are rare and suggest that these molecules may be functionally impaired despite their preserved expression.

OBSERVATION: We report the case of a 3-year-and-8-month-old female with a family history of LAD type I due to absent adhesion molecule expression. The patient experienced recurrent hospitalizations since the neonatal period for multiple infections, predominantly ecthyma gangrenosum and purulent otitis media. Immunological analysis revealed normal surface expression of adhesion molecules, contrasting with her severe clinical and laboratory phenotype suggestive of LAD. Genetic testing identified two variants in ITGB2: a pathogenic deletion (c.119_128del) inherited from her healthy father and a missense variant (c.700G>A), classified as likely pathogenic, inherited from her healthy mother. Notably, the c.700G>A variant has not been previously reported in association with LAD syndrome. These findings suggest that the compoundsite heterozygosity of these two variants may be associated with the observed phenotype.

CONCLUSION

LAD type I may present in children with apparently normal expression of adhesion molecules. Functional studies are warranted to assess the impact of the c.700G>A variant, which may affect protein function despite preserved expression.