ICON: The Early Diagnosis of Congenital Immunodeficiencies

Primary immunodeficiencies are intrinsic defects in the immune system that result in a predisposition to infection and are frequently accompanied by a propensity to autoimmunity and/or immunedysregulation. Primary immunodeficiencies can be divided into innate immunodeficiencies, phagocytic deficiencies, complement deficiencies, disorders of T cells and B cells (combined immunodeficiencies), antibody deficiencies and immunodeficiencies associated with syndromes. Diseases of immune dysregulation and autoinflammatory disorder are many times also included although the immunodeficiency in these disorders are often secondary to the autoimmunity or immune dysregulation and/or secondary immunosuppression used to control these disorders. Congenital primary immunodeficiencies typically manifest early in life although delayed onset are increasingly recognized. The early diagnosis of congenital immunodeficiencies is essential for optimal management and improved outcomes. In this International Consensus (ICON) document, we provide the salient features of the most common congenital immunodeficiencies.     

Prevalence of primary immunodeficiency in Korea

This study represents the first epidemiological study based on the national registry of primary immunodeficiencies (PID) in Korea. Patient data were collected from 23 major hospitals. A total of 152 patients with PID (under 19 yr of age), who were observed from 2001 to 2005, have been entered in this registry. The period prevalence of PID in Korea in 2005 is 11.25 per million children. The following frequencies were found: antibody deficiencies, 53.3% (n = 81), phagocytic disorders, 28.9% (n = 44); combined immunodeficiencies, 13.2% (n = 20); and T cell deficiencies, 4.6% (n = 7). Congenital agammaglobulinemia (n = 21) and selective IgA deficiency (n = 21) were the most frequently reported antibody deficiency. Other reported deficiencies were common variable immunodeficiencies (n = 16), X-linked agammaglobulinemia (n = 15), IgG subclass deficiency (n = 4). Phagocytic disorder was mostly chronic granulomatous disease. A small number of patients with Wiskott-Aldrich syndrome, hyper-IgE syndrome, and severe combined immunodeficiency were also registered. Overall, the most common first manifestation was pneumonia. This study provides data that permit a more accurate estimation PID patients in Korea.     

Frequency and Clinical Manifestations of Patients with Primary Immunodeficiency Disorders in Iran: Update from the Iranian Primary Immunodeficiency Registry

Primary immunodeficiency disorders (PID) are a heterogeneous group of diseases, characterized by an increased susceptibility to infections. A total of 930 patients (573 males and 357 females) are registered in Iranian PID Registry (IPIDR) during three decades. Predominantly antibody deficiencies were the most common (38.4%), followed by congenital defects of phagocyte number and/or function (28.3%), other well-defined immunodeficiency syndromes (17.7%), combined T- and B-cell immunodeficiencies (11.0%), complement deficiencies (2.4%), and diseases of immune dysregulation (2.3%). Common variable immunodeficiency was the most frequent disorder (20.8%), followed by chronic granulomatous disease, ataxia-telangiectasia, btk deficiency, selective IgA deficiency, and T-B-severe combined immunodeficiency. The frequency of other PID disorders was less than 50 in number (<5%). There is an increasing trend in recognition of more PID in the recent years. Construction of such registry is not only important for its epidemiological aspect but also for its role in increasing the physician's knowledge about such disorders.     

SLE and infections

Infections are common in systemic lupus erythematosus (SLE), and remain a source of mortality. The types of infections (such as pneumonia, urinary tract infection, cellulitis, and sepsis) in SLE patients are similar to the general population and include the same pathogens (Gram-positive and Gram-negative). SLE patients may also develop opportunistic infections, especially when treated with immunosuppressive agents. As a high-risk population, identification and treatment of chronic infections such as tuberculosis, hepatitis B, or human immunodeficiency virus (HIV), are important prior to the institution of immunosuppression to prevent reactivation or exacerbation of the infection. A common caveat is to distinguish between a lupus flare and an acute infection; judicious use of corticosteroids and cytotoxic drugs is critical in limiting infectious complications. The risk factors associated with susceptibility to disease include severe flares, active renal disease, treatment with moderate or high doses of corticosteroids and/or immunosuppressive agents, and others. Genetic factors (complement deficiencies, mannose-binding lectin, Fcgamma III, granulocyte macrophage colony-stimulating factor [GM-CSF], osteopontin) may predispose certain SLE patients to develop infections. Parameters including C-reactive protein (CRP) and adhesion molecules may help to differentiate an infectious disease from an exacerbation of the disease. Finally, the mechanism of molecular mimicry by specific microbial agents may play a role in the induction of SLE.     

Viral infection in primary antibody deficiency syndromes

Patients with primary antibody deficiency syndromes such as X‐linked agammaglobulinemia (XLA) and common variable immunodeficiency (CVID) are at increased risk of severe and invasive infection. Viral infection in these populations has been of increasing interest as evidence mounts that viruses contribute significant morbidity and mortality: this is mediated both directly and via aberrant immune responses. We explain the importance of the humoral immune system in defence against viral pathogens before highlighting several significant viral syndromes in patients with antibody deficiency. We explore historical cases of hepatitis C via contaminated immunoglobulin products, the predisposition to invasive enteroviral infections, prolonged excretion of vaccine‐derived poliovirus, the morbidity of chronic norovirus infection, and recent literature revealing the importance of respiratory viral infections. We discuss evidence that herpesviruses may play a role in driving the inflammatory disease seen in a subset of patients. We explore the phenomenon of within‐host evolution during chronic viral infection and the potential emergence of new pathogenic strains. We highlight novel and emerging viruses identified via deep sequencing techniques. We describe the treatment strategies that have been attempted in all these scenarios and the urgent outstanding questions for research.     

Primary Immunodeficiency Diseases in Egyptian Children: A Single-Center Study

Introduction  Sixty-four primary immunodeficiency patients were registered at the Pediatric Allergy and Immunology Department, Children’s Hospital, Ain Shams University, Cairo, Egypt. Data  Predominantly antibody deficiencies were the most common category (35.9%) followed by combined T- and B-cell immunodeficiencies (29.7%), other well defined immunodeficiency syndromes (18.7%), congenital defects of phagocyte number, function or both (12.5%), and diseases of immune dysregulation (3.1%). The most frequent disorder was common variable immunodeficiency (18.7%). The mean age at diagnosis was 29.9 months. The consanguinity rate was 62.5%. Recurrent severe infections were seen in all categories. Fifteen patients died (23.4%) from infections with the highest mortality for combined T- and B-cell immunodeficiencies (15.6%). Conclusions  Primary immunodeficiency disorders are not rare in Egyptian children. The observed frequency of combined T- and B-cell immunodeficiencies in our cohort is relatively higher than other countries. It is a prerequisite to establish a national registry of primary immunodeficiency in Egypt.     

Primary immunodeficiency diseases associated with increased susceptibility to viral infections and malignancies

Primary immunodeficiencies (PIDs) are commonly characterized by an increased susceptibility to specific infections and, in certain instances, a higher than usual incidence of malignancies. Although improved diagnosis and early treatment of PIDs have reduced early morbidity and mortality from infection, the development of cancer remains a significant cause of premature death. The emergence of cancer in patients with PIDs often results from impairments in the immune response that lead to weakened surveillance against oncogenic viruses, premalignant or malignant cells, or both. Here we review the clinical and biologic features of several PIDs associated with enhanced susceptibility to viral infections and cancer, including X-linked lymphoproliferative disease; IL-2-inducible T-cell kinase deficiency; epidermodysplasia verruciformis; warts, hypogammaglobulinemia, infections, and myelokathexis syndrome; autosomal recessive hyper-IgE syndrome; X-linked agammaglobulinemia; and common variable immunodeficiency. It is of importance that we gain in-depth insights into the fundamental molecular nature of these unique PIDs to better understand the pathogenesis of virus-associated malignancies and to develop innovative therapeutic strategies.     

Hypogammaglobulinaemia

This article reviews the primary immunodeficiencies that result in hypogammaglobulinemia or predominantly antibody deficiency disorders. This group makes up the largest proportion of patients with primary immunodeficiency. Significant advances have been made in understanding the molecular basis and clinical characteristics of patients with the more severe forms of antibody deficiency in the last 6 years. Recognition of these disorders remains poor with significant diagnostic delay. The milder forms of antibody deficiency disorders, especially those with normal total serum immunoglobulin G levels, remain poorly characterized and understood. Further work remains to be done in understanding and recognizing these syndromes to benefit patient care and foster further knowledge of the immune system.     

Autoimmunity in primary T-cell immunodeficiencies

Primary immunodeficiency diseases (PID) are a genetically heterogeneous group of more than 270 disorders that affect distinct components of both humoral and cellular arms of the immune system. Primary T cell immunodeficiencies affect subjects at the early age of life. In most cases, T-cell PIDs become apparent as combined T- and B-cell deficiencies. Patients with T-cell PID are prone to life-threatening infections. On the other hand, non-infectious complications such as lymphoproliferative diseases, cancers and autoimmunity seem to be associated with the primary T-cell immunodeficiencies. Autoimmune disorders of all kinds (organ specific or systemic ones) could be subjected to this class of PIDs; however, the most frequent autoimmune disorders are immune thrombocytopenic purpura (ITP) and autoimmune hemolytic anemia (AIHA). In this review, we discuss the proposed mechanisms of autoimmunity and review the literature reported on autoimmune disorder in each type of primary T-cell immunodeficiencies.     

T cell immunodeficiency

T cell immunodeficiency can occur as one of a group of primary disorders or develop secondary to chronic infection, illness or drug therapy. Primary T cell disorders are rare, accounting for approximately 11% of reported primary immunodeficiencies, and generally present in infancy or early childhood. Early recognition is very important as many of these patients will require bone marrow transplantation prior to the onset of severe infection or other complications. Because of their rarity, these infants usually present to clinicians who have little or no prior experience of these conditions, and therefore laboratory-based clinicians with knowledge of the key laboratory/pathological abnormalities and clinical features have a valuable role in identifying the possibility of immunodeficiency. Secondary T cell deficiency is a cardinal feature of HIV infection and the specific susceptibility to infectious micro-organisms is highlighted. The possibility of T cell immunodeficiency should be considered in any patient presenting with unusual or severe viral, fungal or protozoal infection.     

Assessment and clinical interpretation of polysaccharide antibody responses.

This second article in the miniseries Practical Aspects of Ambulatory Diagnosis and Management of Immunodeficiency Disorders' extends the discussion on evaluation of individuals with suspected humoral immunodeficiency by reviewing the logistics and interpretation of the patient's ability to produce antibodies to polysaccharide antigens, specifically pneumococcal surface polysaccharides. The response to these polysaccharides is important in the evaluation of patients with documented immune abnormalities and those individuals who have normal total immunoglobulin levels. Although profound immune deficiencies, such as X-linked agammaglobulinemia and severe combined immunodeficiency, are always associated with a defect in specific antibody production, some immune disorders may have variable responses, whereas others with persistent IgG or IgG subclass deficiencies may have normal or clearly abnormal antipolysaccharide antibodies. Measurement of the response to pneumococcal polysaccharides is preferred because of the availability of a pure polysaccharide vaccine for antigen challenge and standardized techniques to measure specific antibody responses.     

Neutropenia and Primary Immunodeficiency Diseases

Primary immunodeficiency diseases (PID) are a heterogeneous group of congenital disorders of the immune system leading to recurrent infections, autoimmunity, malignancies, and hematological disorders. This review focuses specifically on inherited disorders associated with neutropenia, which may occur in isolation or as a feature of more complex immune disorders. It has been known for a long time that defined immunodeficiency syndromes, such as CD40L deficiency, WHIM syndrome, or Chédiak Higashi syndrome, may be associated with neutropenia even though the mechanisms are poorly understood. In some PID, neutropenia may result from chronic viral infection or from autoimmunity. Recently, the identification of several novel genetic defects (e.g., p14-deficiency, HAX1-deficiency, AK2-deficiency) has shed light on the pathophysiology of congenital neutropenia. This review summarizes the clinical, immunological, and genetic features of congenital neutropenia syndromes.     

Epstein-Barr virus-associated smooth muscle tumors in ataxia-telangiectasia: a case report and review

Chromosomal breakage syndromes, including ataxia-telangiectasia (AT), are autosomal recessive disorders in which DNA repair mechanisms are defective resulting in chromosomal instability. Affected individuals are at high risk for developing malignancy because of the widespread resulting cellular effects. One such effect, severe immunosuppression, can permit virally mediated neoplasms to manifest, similar to those seen in acquired immunodeficiency syndrome (AIDS), congenital immune deficiency syndromes, and posttransplant populations. Epstein-Barr virus (EBV) is a common viral agent known to be associated with lymphoid, epithelial, and smooth muscle malignancies in such patients. Although smooth muscle tumors have been reported in patients with AT, their association with EBV has not been evaluated. We present a case of EBV-associated laryngeal leiomyosarcoma and jejunal cellular leiomyoma in a child with AT. This case suggests that the development of neoplasia in patients with chromosomal breakage syndromes may be related to the immunosuppressive consequences of these diseases, and searching for infectious causes (such as EBV) is important.     

Growth failure, intracranial calcifications, acquired pancytopenia, and unusual humoral immunodeficiency: a genetic syndrome?

We report on two children who may represent a novel syndrome consisting of a deficiency of immunoglobulin-bearing B lymphocytes and serum antibody, deficient intrauterine and/or postnatal growth, intracranial calcifications, and acquired pancytopenia. Poor growth, intracranial calcifications, developmental delay, and hematological abnormalities are common manifestations of congenital infection. However, humoral immunodeficiency is not characteristic in these infections, and no infection was found on extensive evaluation. Rare genetic syndromes may mimic intrauterine infections and may also include immunodeficiency. However the children reported here lack important characteristics or share distinctive manifestations not described in these disorders. Infants presenting with apparent congenital infections in whom a specific infectious cause cannot be identified should be followed carefully with immunological evaluations since this disorder may be progressive and considerable morbidity is attributable to hematological and immunological manifestations.     

Distribution of primary immunodeficiency diseases diagnosed in a pediatric tertiary hospital.

BACKGROUND: Advances in immunologic techniques in recent years have led to increased recognition of primary immunodeficiency disorders, with IgA deficiency the most common phenotype reported by most registries. There have also been reports of increased associated incidence of autoimmunity, allergy, and other diseases. OBJECTIVES: We wished to determine the percentage of different primary immunodeficiency disorders seen in a pediatric tertiary hospital and to determine the association of primary immunodeficiency disorders with other diseases that are not part of classic immunodeficiency disorders. METHODS: We performed a retrospective review of the patients referred to our allergy/immunology clinic for immunologic evaluation of recurrent infections during an 8-year period. We also reviewed pathology reports with postmortem diagnosis of immunodeficiencies not identified while patients were alive. RESULTS: Of the 91 patients with primary immunodeficiency disorders evaluated, the majority had predominantly antibody deficiencies (67%). The most common phenotype was specific antibody deficiency with normal immunoglobulins (23.1%), defined as inability to mount an adequate response to pneumococcal polysaccharides followed by IgG2 subclass deficiency (17.6%). These two phenotypes were diagnosed mostly in the last 2 years of the survey. Associated diseases, found in 40% of patients, were mostly allergic conditions followed by syndromic/chromosomal disorders. CONCLUSION: The study reveals that specific antibody deficiency with normal immunoglobulins followed by IgG2 subclass deficiency was the most frequently diagnosed primary immunodeficiency disorder in our patient population. It also indicates that immunodeficiency disorders should be considered in patients with other abnormalities like allergic and syndromic/chromosomal disorders that present with recurrent infections.     

Humoral immunodeficiency

Humoral (or antibody) immunodeficiency syndromes may occur as apparent congenital or acquired abnormalities, with deficiencies in all or in only some classes of immunoglobulins. Most patients are recognized because of recurrent infections with high-grade extracellular encapsulated bacterial pathogens, but some with selective IgA deficiency or with transient hypogammaglobulinemia of infancy may have few or no infections. Although general population statistics are not available, most defects are thought to be rare; humoral immunodeficiency is more prevalent than cellular immunodeficiency, possibly due to early death from the latter defects. Disorders affecting B-cell function may be inherited as X-linked recessive or as autosomal traits. Although considerable information exists about such defects at a functional and cellular level, the primary biologic errors are as yet unknown for all of them. Apparent abnormalities of B-cell maturation and/or intrinsic B-cell malfunction are seen in a majority of these defects. The heterogeneity of B-cell morphology and function in large pedigrees of patients with X-linked agammaglobulinemia makes it unlikely that the defect is due to a distinct gene rearrangement abnormality at a specific stage of B-cell maturation. Early recognition of B-cell deficiency and institution of adequate immunoglobulin replacement therapy can prevent extensive damage to the lungs and other life-threatening problems from infection and allow a relatively normal childhood and adult life.     

Insights into immunity from clinical and basic science studies of DOCK8 immunodeficiency syndrome

DOCK8 immunodeficiency syndrome (DIDS) is a progressive combined immunodeficiency that can be distinguished from other combined immunodeficiencies or hyperimmunoglobulinemia E syndromes in featuring (a) profound susceptibility to virus infections of the skin, with associated skin cancers, and (b) severe food allergies. The DOCK8 locus has many repetitive sequence elements that predispose to the generation of large germline deletions as well as recombination‐mediated somatic DNA repair. Residual DOCK8 protein contributes to the variable disease phenotype. The severe virus infections of the skin, and probably also VZV‐associated vasculopathy, reflect an important function of DOCK8, which is normally required to maintain lymphocyte shape integrity as the cells migrate through dense tissues. Loss of DOCK8 also causes immune deficits through other mechanisms including a milder generalized cell survival defect and skewing of T helper cell subsets. Recent work has uncovered the roles for DOCK8 in dendritic cell responses that can also help explain the virus susceptibility, as well as in regulatory T cells that might help explain autoimmunity in a minority of patients. Fortunately, hematopoietic stem cell transplantation cures the eczema and infection susceptibility of DIDS, but not necessarily the other disease manifestations including food allergies.     

Primary immunodeficiencies in Switzerland: First report of the national registry in adults and children

This first report of a Swiss registry includes 313 patients with primary immunodeficiency syndromes (PIDS) who were observed between January 1975 and January 1985. Diagnosis of specific PIDS was made according to WHO criteria. The most frequent disorders were IgA deficiency (33%) and common variable immunodeficiency (22%), followed by selective deficiency of other immunoglobulin isotypes (9%), severe combined immunodeficiency (9%), infantile sex-linked agammaglobulinemia (7%), and Wiskott-Aldrich syndrome (6%). Frequencies of other types of PIDS varied between 0.3 and 4%. Half of the patients were in the pediatric age group. Male patients predominated (63%). In addition to respiratory and urogenital tract infections, autoimmune disorders were observed in 14 patients with IgA deficiency or common variable immunodeficiency. IgA deficiency was, furthermore, associated with atopic and neurological disorders. A comparison with other national registries revealed some differences: the frequency of severe combined immunodeficiency was high (incidence, 24.3 cases per 10⁶ live births), and that of ataxia teleangiectasia was particularly low (1.4 per 10⁶ live births) in Switzerland. Frequencies of the three major PIDS groups of (i) predominantly antibody defects, (ii) predominantly cell-mediated defects, and (iii) PIDS associated with other major defects agreed with those reported in the other European studies.     

Immunodeficiency as a component of recognizable syndromes

Immunodeficiency occurs in numerous genetic syndromes. While it is the dominant manifestation in primary immunodeficiencies, immune deficits may also be seen in a variety of other recognizable syndromes. Immunodeficiency has been reported in 64 such conditions, adding to the 45 recognized primary immunodeficiencies. These uncommon syndromes with immune defects can present with: (a) growth deficiency (11 syndromes with disproportionate or proportionate short stature), (b) specific organ system dysfunction (18 with gastrointestinal, dermatologic, or neurologic abnormalities), (c) inborn errors of metabolism (13), (d) miscellaneous anomalies (10), or (e) chromosome anomalies (12). In most of the disorders, only some of the affected patients have immune defects. However, in 27 syndromes, immunodeficiency is a constant finding. We briefly review the clinical manifestations of each syndrome and delineate the specific associated immune defects. In most syndromes, the connection between the immune and other defects is unknown. Recognition of these conditions involving both the immune and other organ systems may facilitate accurate diagnosis and management as well as yield information regarding genes critical for the development of the involved systems. © 1996 Wiley-Liss, Inc.     

Antibody deficiency

Antibody deficiencies may arise as primary disorders or secondary to a variety of diseases, drugs and other environmental/iatrogenic factors. Significant primary antibody deficiencies are relatively rare but, collectively, account for the majority of primary immunodeficiency syndromes encountered in clinical practice. The genetic basis of a number of primary deficiencies has been clarified, although there is considerable genotype/phenotype heterogeneity and the role of gene/environment interactions has yet to be fully elucidated. Primary antibody deficiency can present at any age. The hallmark clinical presentation is recurrent bacterial infection, but these disorders are also associated with a wide variety of other infectious and non-infectious complications and with a high incidence of chronic, structural tissue damage, particularly in the respiratory tract. Clinical recognition of primary antibody deficiency is frequently delayed with consequent increased morbidity, diminished quality of life and early mortality. Clinical laboratories can contribute to improved and timely detection through awareness of routine test results which may be overtly or indirectly suggestive of antibody deficiency. Secondary deficiency is associated with increased awareness, better recognition and earlier diagnosis than in primary disorders. Early liaison and referral of patients with suspected antibody deficiency for specialist opinion and prompt, appropriate therapy is central to the achievement of good clinical outcomes.