Immunoglobulin M Deficiency Introduction Background Selective immunoglobulin M deficiency (SIgMD) is a rare form of dysgammaglobulinemia characterized by an isolated low level of serum immunoglobulin M (IgM). Reported IgM concentrations in SIgMD vary from 40 mg/dL (though some sources say 20 mg/dL) to undetectable levels (reference range 45-150 mg/dL in adults) (Sorenson, 2000). Values in children must be compared with reference range values for age (Ballow, 2002). The levels of other immunoglobulin classes are within reference ranges. SIgMD may occur…
Immunoglobulin G Deficiency Introduction Background Immunodeficiency diseases are commonly classified into disorders that affect one or more of the 4 major limbs of the immune system. These limbs are (1) B cells, ie, humoral immunity; (2) T cells, ie, cell-mediated immunity; (3) phagocytes; and (4) complement.
Immunoglobulin D Deficiency Introduction Background Immunoglobulin D (IgD) deficiency is a defect of humoral immunity that is characterized by abnormally low serum levels of IgD immunoglobulins. Little is known about the normal function of IgD, and few clinical signs or symptoms are associated with its absence. Individuals with low or absent levels of IgD do not appear unusually predisposed to infections. Pathophysiology
Hypogammaglobulinemia Introduction Background Hypogammaglobulinemia is a clinicolaboratory entity with varied causes and manifestations. Several codes in the International Classification of Diseases, 9th edition (ICD-9) relate to disorders in which hypogammaglobulinemia is a primary feature. These include deficiencies of humoral immunity, which is coded 279.0. The common clinical feature of hypogammaglobulinemia relates to a predisposition toward infections, which normally are defended against by antibody responses.
DiGeorge Syndrome Introduction Background Conditions associated with DiGeorge syndrome are 22q11 deletion syndromes, velocardiofacial syndrome (VCFS or Shprintzen syndrome), conotruncal anomaly face syndrome, Cayler syndrome, Opitz-GBBB syndrome, and CHARGE (coloboma [eye], heart anomaly, atresia [choanal], retardation [mental and growth], genital anomaly, ear anomaly) syndrome. DiGeorge anomaly (DGA) is a congenital immunodeficiency characterized by abnormal facies; congenital heart defects; hypoparathyroidism with hypocalcemia; cognitive, behavioral, and psychiatric problems; and increased susceptibility to infections. Pathological hallmarks include conotruncal abnormalities and absence or hypoplasia…
Hypocomplementemia Introduction Background In the late 19th century, serum was found to contain a nonspecific heat-labile complementary principle that interacted with antibodies to induce bacteriolysis. Ehrlich and Morgan termed this factor complement. The complement system as understood today is a multimolecular system composed of more than 20 proteins and consisting of serum proteins, serosal proteins, and cell membrane receptors that bind to complement fragments. They constitute 10% of the globulin fraction of serum. Many of these proteins are designated by…
Hereditary Angioedema Introduction Background Hereditary angioedema (HAE) is an inherited disease caused by low levels of the plasma protein C1 inhibitor (C1-INH). Acquired angioedema (AAE) is caused by a consumption of C1-INH (for various reasons) that leads to low levels of this protein (see Angioedema). Deficiencies in this protein allow unchecked activation of the classic complement pathway and other biochemical systems.
Complement Deficiencies Introduction Background The complement system is part of the innate immune system. The complement system plays an important part in defense against pyogenic organisms. It promotes the inflammatory response, eliminates pathogens, and enhances the immune response. Deficiencies in the complement cascade can lead to overwhelming infection and sepsis.
Vocal Cord Dysfunction Introduction Background Vocal cord dysfunction (VCD) can be characterized as an abnormal adduction of the vocal cords during the respiratory cycle (especially during the inspiratory phase) that produces airflow obstruction at the level of the larynx. VCD frequently mimics persistent asthma and is often treated with high-dose inhaled and/or systemic corticosteroids, bronchodilators, multiple emergency department visits, hospitalizations, and in some cases, tracheostomies and intubation.
Allergic and Environmental Asthma Introduction Background Asthma is a clinical syndrome characterized by episodic reversible airway obstruction, increased bronchial reactivity, and airway inflammation. Asthma results from complex interactions among inflammatory cells, their mediators, airway epithelium and smooth muscle, and the nervous system. In genetically susceptible individuals, these interactions can lead the patient with asthma to symptoms of breathlessness, wheezing, cough, and chest tightness.