Periodic fever, immunodeficiency, and thrombocytopenia syndrome (PFITS) is an autosomal recessive immunologic disorder with variable manifestations. Common features include early-onset recurrent respiratory infections, stomatitis, and cutaneous infections. Organisms usually include bacteria such as pneumococcus, Staphylococcus, and H. influenzae, but severe viral infections, including varicella, may also occur. Laboratory investigations may show neutropenia, neutrophilia, leukocytosis, or lymphopenia, although levels of immune cells may also be normal. Detailed studies often show impaired neutrophil chemotaxis associated with increased or abnormal F-actin levels, and impaired, normal, or even increased oxidative burst, depending on the stimulus. B- and T-cell abnormalities have also been observed. Some patients develop autoimmune manifestations, including chronic thrombocytopenia, anemia, and periodic fevers, associated with activation of the inflammasome. Early death may occur; however, hematopoietic stem cell transplantation may be curative (summary by Kuhns et al., 2016, Standing et al., 2017, and Pfajfer et al., 2018).

Immunodeficiency-68 (IMD68) is an autosomal recessive primary immunodeficiency characterized by severe systemic and invasive bacterial infections beginning in infancy or early childhood. The most common organisms implicated are Streptococcus pneumoniae, Staphylococcus aureus, and Pseudomonas, although other organisms may be observed. IMD68 is life-threatening in infancy and early childhood. The first invasive infection typically occurs before 2 years of age, with meningitis and upper respiratory infections being common manifestations. 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. Viral, fungal, and parasitic infections are generally not 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, IMD68 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 Picard et al., 2010). See also IMD67 (607676), caused by mutation in the IRAK4 gene (602170), which shows a similar phenotype to IMD68. 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).

Chronic recurrent multifocal osteomyelitis-2 with periostitis and pustulosis (CRMO2) is an autosomal recessive multisystemic autoinflammatory disorder characterized by onset of symptoms in early infancy. Affected individuals present with joint swelling and pain, pustular rash, oral mucosal lesions, and fetal distress. The disorder progresses in severity to generalized severe pustulosis or ichthyosiform lesions and diffuse bone lesions. Radiographic studies show widening of the anterior rib ends, periosteal elevation along multiple long bones, multifocal osteolytic lesions, heterotopic ossification, and metaphyseal erosions of the long bones. Laboratory studies show elevation of inflammatory markers. The disorder results from unopposed activation of the IL1 inflammatory signaling pathway. Treatment with the interleukin-1 receptor antagonist anakinra may result in clinical improvement (Aksentijevich et al., 2009). For a discussion of genetic heterogeneity of CRMO, see 609628.

Immunodeficiency-22 (IMD22) is an autosomal recessive disorder characterized by the onset of recurrent bacterial, viral, and fungal respiratory, gastrointestinal, and skin infections in infancy or early childhood. Immunologic workup shows severe T-cell lymphopenia, particularly affecting the CD4+ subset, and impaired proximal TCR intracellular signaling and activation. Although NK cells and B cells are normal, some patients may have hypogammaglobulinemia secondary to the T-cell defect. There are variable manifestations, likely due to the severity of the particular LCK mutation: patients may develop prominent skin lesions resembling epidermodysplasia verruciformis, gastrointestinal inflammation, and virus-induced malignancy. The disease can be fatal in childhood, but hematopoietic stem cell transplant (HSCT) may be curative (Hauck et al., 2012; Li et al., 2016; Keller et al., 2023).

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).

Chronic granulomatous disease (CGD) is a primary immunodeficiency disorder of phagocytes (neutrophils, monocytes, macrophages, and eosinophils) resulting from impaired killing of bacteria and fungi. CGD is characterized by severe recurrent bacterial and fungal infections and dysregulated inflammatory responses resulting in granuloma formation and other inflammatory disorders such as colitis. Infections typically involve the lung (pneumonia), lymph nodes (lymphadenitis), liver (abscess), bone (osteomyelitis), and skin (abscesses or cellulitis). Granulomas typically involve the genitourinary system (bladder) and gastrointestinal tract (often the pylorus initially, and later the esophagus, jejunum, ileum, cecum, rectum, and perirectal area). Some males with X-linked CGD have McLeod neuroacanthocytosis syndrome as the result of a contiguous gene deletion. While CGD may present anytime from infancy to late adulthood, the vast majority of affected individuals are diagnosed before age five years. Use of antimicrobial prophylaxis and therapy has greatly improved overall survival.

Immunodeficiency-81 (IMD81) is an autosomal recessive complex immunologic disorder with onset of symptoms in infancy. The phenotype is highly variable and may include both immunodeficiency with recurrent infections, including bacterial and fungal infections, as well as autoimmune features, including autoimmune hemolytic anemia, pancytopenia, thrombocytopenia, and inflammatory bowel disease. Immunologic workup shows immune dysregulation with abnormalities affecting multiple immune cell lineages, including T cells, B cells, NK cells, and neutrophils, which may be decreased or increased and demonstrate functional deficits. There is a wide range of hematologic abnormalities. Affected individuals may be susceptible to severe EBV infection. The disorder is caused by a defect in intracellular immune signaling pathways (summary by Lev et al., 2021; Edwards et al., 2023).