Leukocyte adhesion deficiency (LAD) is an autosomal recessive disorder of neutrophil function resulting from a deficiency of the beta-2 integrin subunit of the leukocyte cell adhesion molecule. The leukocyte cell adhesion molecule is present on the surface of peripheral blood mononuclear leukocytes and granulocytes and mediates cell-cell and cell-extracellular matrix adhesion. LAD is characterized by recurrent bacterial infections; impaired pus formation and wound healing; abnormalities of a wide variety of adhesion-dependent functions of granulocytes, monocytes, and lymphocytes; and a lack of beta-2/alpha-L, beta-2/alpha-M, and beta-2/alpha-X expression. Genetic Heterogeneity of Leukocyte Adhesion Deficiency Also see LAD2 (266265), caused by mutation in the SLC35C1 gene (605881), and LAD3 (612840), caused by mutation in the FERMT3 gene (607901).

Immunodeficiency-67 (IMD67) is an autosomal recessive primary immunodeficiency characterized by recurrent severe systemic and invasive bacterial infections beginning in infancy or early childhood. The most common organisms implicated are Streptococcus pneumoniae and Staphylococcus aureus; Pseudomonas and atypical Mycobacteria may also be observed. IMD67 is life-threatening in infancy and early childhood. The first invasive infection typically occurs before 2 years of age, with meningitis representing up to 41% of the bacterial infections. The mortality rate in early childhood is high, with most deaths occurring before 8 years of age. Affected individuals have an impaired inflammatory response to infection, including lack of fever and neutropenia, although erythrocyte sedimentation rate (ESR) and C-reactive protein may be elevated. General immunologic workup tends to be normal, with normal levels of B cells, T cells, and NK cells. However, more detailed studies indicate impaired cytokine response to lipopolysaccharide (LPS) and IL1B (147720) stimulation; response to TNFA (191160) is usually normal. Patients have good antibody responses to most vaccinations, with the notable exception of pneumococcal vaccination. Viral, fungal, and parasitic infections are not generally observed. Early detection is critical in early childhood because prophylactic treatment with IVIg or certain antibiotics is effective; the disorder tends to improve naturally around adolescence. At the molecular level, the disorder results from impaired function of selective Toll receptor (see TLR4, 603030)/IL1R (see IL1R1, 147810) signaling pathways that ultimately activate NFKB (164011) to produce cytokines (summary by Ku et al., 2007; Picard et al., 2010; Grazioli et al., 2016). See also IMD68 (612260), caused by mutation in the MYD88 gene (602170), which shows a similar phenotype to IMD67. As the MYD88 and IRAK4 genes interact in the same intracellular signaling pathway, the clinical and cellular features are almost indistinguishable (summary by Picard et al., 2010).

IMD23 is an autosomal recessive primary immunodeficiency syndrome characterized by onset of recurrent infections, usually respiratory or cutaneous, in early childhood. Immune workup usually shows neutropenia, lymphopenia, eosinophilia, and increased serum IgE or IgA. Neutrophil chemotactic defects have also been reported. Infectious agents include bacteria, viruses, and fungi. Many patients develop atopic dermatitis, eczema, and other signs of autoinflammation. Affected individuals may also show developmental delay or cognitive impairment of varying severity (summary by Bjorksten and Lundmark, 1976 and Zhang et al., 2014).