X-linked Agammaglobulinemia

Epidemiology and Pathophysiology

Epidemiology

• 1:200,000 live births 
• 1:100,000 male newborns
• Occurs more commonly in boys due to X-linked recessive X-Linked Recessive Duchenne Muscular Dystrophy inheritance pattern
• No ethnic predisposition

Etiology

• The most common X-linked recessive X-Linked Recessive Duchenne Muscular Dystrophy disorder found in males; females are usually asymptomatic carriers Carriers The Cell: Cell Membrane
  • Males have an XY karyotype Karyotype The full set of chromosomes presented as a systematized array of metaphase chromosomes from a photomicrograph of a single cell nucleus arranged in pairs in descending order of size and according to the position of the centromere. Congenital Malformations of the Female Reproductive System and only possess 1 X chromosome X chromosome The female sex chromosome, being the differential sex chromosome carried by half the male gametes and all female gametes in human and other male-heterogametic species. Basic Terms of Genetics.
  • Females would require 2 affected X chromosomes Chromosomes In a prokaryotic cell or in the nucleus of a eukaryotic cell, a structure consisting of or containing DNA which carries the genetic information essential to the cell. DNA Types and Structure to develop the disease.
• Caused by a mutation Mutation Genetic mutations are errors in DNA that can cause protein misfolding and dysfunction. There are various types of mutations, including chromosomal, point, frameshift, and expansion mutations. Types of Mutations in the Bruton’s tyrosine Tyrosine A non-essential amino acid. In animals it is synthesized from phenylalanine. It is also the precursor of epinephrine; thyroid hormones; and melanin. Synthesis of Nonessential Amino Acids kinase (Btk) gene Gene A category of nucleic acid sequences that function as units of heredity and which code for the basic instructions for the development, reproduction, and maintenance of organisms. Basic Terms of Genetics (this mutation Mutation Genetic mutations are errors in DNA that can cause protein misfolding and dysfunction. There are various types of mutations, including chromosomal, point, frameshift, and expansion mutations. Types of Mutations inhibits B cell maturation into pre-B cells)
• 30%–50% of cases are due to familial genetic inheritance.
• 50%–70% of cases are due to spontaneous mutations.

Pathophysiology

• Mutations in the Btk gene Gene A category of nucleic acid sequences that function as units of heredity and which code for the basic instructions for the development, reproduction, and maintenance of organisms. Basic Terms of Genetics prevent normal B cell maturation from pro-B into pre-B lymphocytes Lymphocytes Lymphocytes are heterogeneous WBCs involved in immune response. Lymphocytes develop from the bone marrow, starting from hematopoietic stem cells (HSCs) and progressing to common lymphoid progenitors (CLPs). B and T lymphocytes and natural killer (NK) cells arise from the lineage. Lymphocytes: Histology.
• Mature B cells B cells Lymphoid cells concerned with humoral immunity. They are short-lived cells resembling bursa-derived lymphocytes of birds in their production of immunoglobulin upon appropriate stimulation. B cells: Types and Functions do not form, and immunoglobulin light chains Immunoglobulin Light Chains Polypeptide chains, consisting of 211 to 217 amino acid residues and having a molecular weight of approximately 22 kda. There are two major types of light chains, kappa and lambda. Two ig light chains and two ig heavy chains (immunoglobulin heavy chains) make one immunoglobulin molecule. Amyloidosis cannot be produced, although free heavy chains Heavy chains The largest of polypeptide chains comprising immunoglobulins. They contain 450 to 600 amino acid residues per chain, and have molecular weights of 51-72 kda. Immunoglobulins: Types and Functions can be found in the cytoplasm. 
• Results in an almost complete absence of immunogammaglobulin (Ig)
• Humoral immunity response is non-functional (with normal T-cell–mediated immunity).
• Patients Patients Individuals participating in the health care system for the purpose of receiving therapeutic, diagnostic, or preventive procedures. Clinician–Patient Relationship are prone to develop serious and even fatal infections Infections Invasion of the host organism by microorganisms or their toxins or by parasites that can cause pathological conditions or diseases. Chronic Granulomatous Disease during early childhood, especially from encapsulated Encapsulated Klebsiella bacteria Bacteria Bacteria are prokaryotic single-celled microorganisms that are metabolically active and divide by binary fission. Some of these organisms play a significant role in the pathogenesis of diseases. Bacteriology.

Clinical Presentation

• Children are asymptomatic until 6–9 months of age when maternal immune protection ( IgG IgG The major immunoglobulin isotype class in normal human serum. There are several isotype subclasses of igg, for example, igg1, igg2a, and igg2b. Hypersensitivity Pneumonitis) previously supplied via the placenta Placenta A highly vascularized mammalian fetal-maternal organ and major site of transport of oxygen, nutrients, and fetal waste products. It includes a fetal portion (chorionic villi) derived from trophoblasts and a maternal portion (decidua) derived from the uterine endometrium. The placenta produces an array of steroid, protein and peptide hormones (placental hormones). Placenta, Umbilical Cord, and Amniotic Cavity falls.
• Presents as recurrent infections Recurrent infections Common Variable Immunodeficiency (CVID) such as:
  • Pneumonia Pneumonia Pneumonia or pulmonary inflammation is an acute or chronic inflammation of lung tissue. Causes include infection with bacteria, viruses, or fungi. In more rare cases, pneumonia can also be caused through toxic triggers through inhalation of toxic substances, immunological processes, or in the course of radiotherapy. Pneumonia
  • Otitis media
  • Cellulitis Cellulitis Cellulitis is a common infection caused by bacteria that affects the dermis and subcutaneous tissue of the skin. It is frequently caused by Staphylococcus aureus and Streptococcus pyogenes. The skin infection presents as an erythematous and edematous area with warmth and tenderness. Cellulitis
  • Conjunctivitis Conjunctivitis Conjunctivitis is a common inflammation of the bulbar and/or palpebral conjunctiva. It can be classified into infectious (mostly viral) and noninfectious conjunctivitis, which includes allergic causes. Patients commonly present with red eyes, increased tearing, burning, foreign body sensation, and photophobia. Conjunctivitis
  • Pharyngitis Pharyngitis Pharyngitis is an inflammation of the back of the throat (pharynx). Pharyngitis is usually caused by an upper respiratory tract infection, which is viral in most cases. It typically results in a sore throat and fever. Other symptoms may include a runny nose, cough, headache, and hoarseness. Pharyngitis
  • Bronchitis
  • Sinusitis Sinusitis Sinusitis refers to inflammation of the mucosal lining of the paranasal sinuses. The condition usually occurs concurrently with inflammation of the nasal mucosa (rhinitis), a condition known as rhinosinusitis. Acute sinusitis is due to an upper respiratory infection caused by a viral, bacterial, or fungal agent. Sinusitis
• Patients Patients Individuals participating in the health care system for the purpose of receiving therapeutic, diagnostic, or preventive procedures. Clinician–Patient Relationship are at especially increased risk for recurrent infections Recurrent infections Common Variable Immunodeficiency (CVID) by:
  • Encapsulated Encapsulated Klebsiella bacteria Bacteria Bacteria are prokaryotic single-celled microorganisms that are metabolically active and divide by binary fission. Some of these organisms play a significant role in the pathogenesis of diseases. Bacteriology, such as:
    • Streptococcus Streptococcus Streptococcus is one of the two medically important genera of gram-positive cocci, the other being Staphylococcus. Streptococci are identified as different species on blood agar on the basis of their hemolytic pattern and sensitivity to optochin and bacitracin. There are many pathogenic species of streptococci, including S. pyogenes, S. agalactiae, S. pneumoniae, and the viridans streptococci. Streptococcus pneumoniae
    • Haemophilus influenzae Haemophilus Influenzae A species of Haemophilus found on the mucous membranes of humans and a variety of animals. The species is further divided into biotypes I through viii. Haemophilus
    • Mycoplasma pneumoniae Mycoplasma pneumoniae Short filamentous organism of the genus mycoplasma, which binds firmly to the cells of the respiratory epithelium. It is one of the etiologic agents of non-viral primary atypical pneumonia in man. Mycoplasma
  • Viruses Viruses Minute infectious agents whose genomes are composed of DNA or RNA, but not both. They are characterized by a lack of independent metabolism and the inability to replicate outside living host cells. Virology, such as:
    • Hepatitis viruses Viruses Minute infectious agents whose genomes are composed of DNA or RNA, but not both. They are characterized by a lack of independent metabolism and the inability to replicate outside living host cells. Virology
    • Enterovirus Enterovirus A genus of the family picornaviridae whose members preferentially inhabit the intestinal tract of a variety of hosts. The genus contains many species. Newly described members of human enteroviruses are assigned continuous numbers with the species designated ‘human enterovirus’. Coxsackievirus
  • Parasitic infections Infections Invasion of the host organism by microorganisms or their toxins or by parasites that can cause pathological conditions or diseases. Chronic Granulomatous Disease, such as Giardia Giardia A genus of flagellate intestinal eukaryotes parasitic in various vertebrates, including humans. Characteristics include the presence of four pairs of flagella arising from a complicated system of axonemes and cysts that are ellipsoidal to ovoidal in shape. Nitroimidazoles lamblia
• Examination shows lymphoid hypoplasia Hypoplasia Hypoplastic Left Heart Syndrome (HLHS), or rudimentary lymph nodes Lymph Nodes They are oval or bean shaped bodies (1 – 30 mm in diameter) located along the lymphatic system. Lymphatic Drainage System: Anatomy, tonsils Tonsils Tonsillitis, Peyer’s patches Patches Vitiligo, and appendix Appendix A worm-like blind tube extension from the cecum. Colon, Cecum, and Appendix: Anatomy.

Diagnosis and Management

Diagnosis

• Suspicion is based on a history of recurrent infections Recurrent infections Common Variable Immunodeficiency (CVID) during childhood, mostly in the respiratory tract.
• Flow Flow Blood flows through the heart, arteries, capillaries, and veins in a closed, continuous circuit. Flow is the movement of volume per unit of time. Flow is affected by the pressure gradient and the resistance fluid encounters between 2 points. Vascular resistance is the opposition to flow, which is caused primarily by blood friction against vessel walls. Vascular Resistance, Flow, and Mean Arterial Pressure cytometry shows:
  • Complete lack or significant reduction of circulating B cells B cells Lymphoid cells concerned with humoral immunity. They are short-lived cells resembling bursa-derived lymphocytes of birds in their production of immunoglobulin upon appropriate stimulation. B cells: Types and Functions determined by the B-cell markers CD19 and CD20
  • Absence of plasma Plasma The residual portion of blood that is left after removal of blood cells by centrifugation without prior blood coagulation. Transfusion Products cells throughout the body
  • Low levels of all antibody classes, including IgG IgG The major immunoglobulin isotype class in normal human serum. There are several isotype subclasses of igg, for example, igg1, igg2a, and igg2b. Hypersensitivity Pneumonitis, IgA IgA Represents 15-20% of the human serum immunoglobulins, mostly as the 4-chain polymer in humans or dimer in other mammals. Secretory iga is the main immunoglobulin in secretions. Immunoglobulins: Types and Functions, IgM IgM A class of immunoglobulin bearing mu chains (immunoglobulin mu-chains). Igm can fix complement. The name comes from its high molecular weight and originally being called a macroglobulin. Immunoglobulins: Types and Functions, IgE IgE An immunoglobulin associated with mast cells. Overexpression has been associated with allergic hypersensitivity. Immunoglobulins: Types and Functions, and IgD IgD An immunoglobulin which accounts for less than 1% of plasma immunoglobulin. It is found on the membrane of many circulating B lymphocytes. Immunoglobulins: Types and Functions
  • Normal-to-high levels of T cells T cells Lymphocytes responsible for cell-mediated immunity. Two types have been identified – cytotoxic (t-lymphocytes, cytotoxic) and helper T-lymphocytes (t-lymphocytes, helper-inducer). They are formed when lymphocytes circulate through the thymus gland and differentiate to thymocytes. When exposed to an antigen, they divide rapidly and produce large numbers of new T cells sensitized to that antigen. T cells: Types and Functions
• Genetic testing Genetic Testing Detection of a mutation; genotype; karyotype; or specific alleles associated with genetic traits, heritable diseases, or predisposition to a disease, or that may lead to the disease in descendants. It includes prenatal genetic testing. Myotonic Dystrophies is used to confirm the diagnosis and identify the specific Btk mutation Mutation Genetic mutations are errors in DNA that can cause protein misfolding and dysfunction. There are various types of mutations, including chromosomal, point, frameshift, and expansion mutations. Types of Mutations.

Management

• There is no cure, but management can increase the patient’s lifespan and quality Quality Activities and programs intended to assure or improve the quality of care in either a defined medical setting or a program. The concept includes the assessment or evaluation of the quality of care; identification of problems or shortcomings in the delivery of care; designing activities to overcome these deficiencies; and follow-up monitoring to ensure effectiveness of corrective steps. Quality Measurement and Improvement of life.
• Mainly consists of lifelong weekly or monthly immunoglobulin replacement therapy ( IVIG IVIG Dermatomyositis)
• Prophylactic antibiotics are administered to prevent infections Infections Invasion of the host organism by microorganisms or their toxins or by parasites that can cause pathological conditions or diseases. Chronic Granulomatous Disease.
• Live vaccines are contraindicated (increased risk of vaccine-related polio)

Differential Diagnosis

The following conditions are differential diagnoses for X-linked X-linked Genetic diseases that are linked to gene mutations on the X chromosome in humans or the X chromosome in other species. Included here are animal models of human X-linked diseases. Common Variable Immunodeficiency (CVID) agammaglobulinemia.

• Autosomal recessive Autosomal recessive Autosomal inheritance, both dominant and recessive, refers to the transmission of genes from the 22 autosomal chromosomes. Autosomal recessive diseases are only expressed when 2 copies of the recessive allele are inherited. Autosomal Recessive and Autosomal Dominant Inheritance or dominant agammaglobulinemia: a rare form of primary immunodeficiency Immunodeficiency Chédiak-Higashi Syndrome disease characterized by a complete or near-complete absence of immunoglobulins Immunoglobulins Immunoglobulins (Igs), also known as antibodies, are glycoprotein molecules produced by plasma cells that act in immune responses by recognizing and binding particular antigens. The various Ig classes are IgG (the most abundant), IgM, IgE, IgD, and IgA, which differ in their biologic features, structure, target specificity, and distribution. Immunoglobulins: Types and Functions, which leads to variable Variable Variables represent information about something that can change. The design of the measurement scales, or of the methods for obtaining information, will determine the data gathered and the characteristics of that data. As a result, a variable can be qualitative or quantitative, and may be further classified into subgroups. Types of Variables immune dysfunction and frequent/recurrent bacterial infections Infections Invasion of the host organism by microorganisms or their toxins or by parasites that can cause pathological conditions or diseases. Chronic Granulomatous Disease. Molecular genetic testing Genetic Testing Detection of a mutation; genotype; karyotype; or specific alleles associated with genetic traits, heritable diseases, or predisposition to a disease, or that may lead to the disease in descendants. It includes prenatal genetic testing. Myotonic Dystrophies is required to determine the causative genetic defect Genetic Defect Ion Channel Myopathy.
• Common variable Variable Variables represent information about something that can change. The design of the measurement scales, or of the methods for obtaining information, will determine the data gathered and the characteristics of that data. As a result, a variable can be qualitative or quantitative, and may be further classified into subgroups. Types of Variables immunodeficiency Immunodeficiency Chédiak-Higashi Syndrome ( CVID CVID Common variable immune deficiency (CVID), also known as humoral immunodeficiency, is a disorder of the immune system characterized by reduced serum levels of immunoglobulins g, a, and m. Common Variable Immunodeficiency (CVID)): a type of primary immunodeficiency Immunodeficiency Chédiak-Higashi Syndrome characterized by reduced serum levels of immunoglobulins Immunoglobulins Immunoglobulins (Igs), also known as antibodies, are glycoprotein molecules produced by plasma cells that act in immune responses by recognizing and binding particular antigens. The various Ig classes are IgG (the most abundant), IgM, IgE, IgD, and IgA, which differ in their biologic features, structure, target specificity, and distribution. Immunoglobulins: Types and Functions IgG IgG The major immunoglobulin isotype class in normal human serum. There are several isotype subclasses of igg, for example, igg1, igg2a, and igg2b. Hypersensitivity Pneumonitis, IgA IgA Represents 15-20% of the human serum immunoglobulins, mostly as the 4-chain polymer in humans or dimer in other mammals. Secretory iga is the main immunoglobulin in secretions. Immunoglobulins: Types and Functions, and IgM IgM A class of immunoglobulin bearing mu chains (immunoglobulin mu-chains). Igm can fix complement. The name comes from its high molecular weight and originally being called a macroglobulin. Immunoglobulins: Types and Functions. The underlying causes of CVID CVID Common variable immune deficiency (CVID), also known as humoral immunodeficiency, is a disorder of the immune system characterized by reduced serum levels of immunoglobulins g, a, and m. Common Variable Immunodeficiency (CVID) are largely unknown. Patients Patients Individuals participating in the health care system for the purpose of receiving therapeutic, diagnostic, or preventive procedures. Clinician–Patient Relationship with this condition are prone to infections Infections Invasion of the host organism by microorganisms or their toxins or by parasites that can cause pathological conditions or diseases. Chronic Granulomatous Disease in the gastrointestinal tract and the upper and lower respiratory tracts and have a higher risk of developing autoimmune, granulomatous, and neoplastic diseases.
• Hyper IgM IgM A class of immunoglobulin bearing mu chains (immunoglobulin mu-chains). Igm can fix complement. The name comes from its high molecular weight and originally being called a macroglobulin. Immunoglobulins: Types and Functions syndrome: a disorder caused by an X-linked X-linked Genetic diseases that are linked to gene mutations on the X chromosome in humans or the X chromosome in other species. Included here are animal models of human X-linked diseases. Common Variable Immunodeficiency (CVID) mutation Mutation Genetic mutations are errors in DNA that can cause protein misfolding and dysfunction. There are various types of mutations, including chromosomal, point, frameshift, and expansion mutations. Types of Mutations in the CD40 CD40 Members of the tumor necrosis factor receptor superfamily with specificity for CD40 ligand. They are found on mature B-lymphocytes, some epithelial cells; and lymphoid dendritic cells. Evidence suggests that CD40-dependent activation of B-cells is important for generation of memory B-cells within the germinal centers. Mutations in the CD40 antigen gene result in hyper-igm immunodeficiency syndrome, type 3. Signaling of the receptor occurs through its association with tnf receptor-associated factors. Hyper-IgM Syndrome ligand gene Gene A category of nucleic acid sequences that function as units of heredity and which code for the basic instructions for the development, reproduction, and maintenance of organisms. Basic Terms of Genetics that results in abnormal signaling between B and T lymphocytes T lymphocytes Lymphocytes responsible for cell-mediated immunity. Two types have been identified – cytotoxic (t-lymphocytes, cytotoxic) and helper T-lymphocytes (t-lymphocytes, helper-inducer). They are formed when lymphocytes circulate through the thymus gland and differentiate to thymocytes. When exposed to an antigen, they divide rapidly and produce large numbers of new T cells sensitized to that antigen. T cells: Types and Functions. Presentation is mild and often only presents in later life as opportunistic infections Infections Invasion of the host organism by microorganisms or their toxins or by parasites that can cause pathological conditions or diseases. Chronic Granulomatous Disease and immune dysregulation of IgE IgE An immunoglobulin associated with mast cells. Overexpression has been associated with allergic hypersensitivity. Immunoglobulins: Types and Functions eosinophils Eosinophils Granular leukocytes with a nucleus that usually has two lobes connected by a slender thread of chromatin, and cytoplasm containing coarse, round granules that are uniform in size and stainable by eosin. Innate Immunity: Phagocytes and Antigen Presentation, B cells B cells Lymphoid cells concerned with humoral immunity. They are short-lived cells resembling bursa-derived lymphocytes of birds in their production of immunoglobulin upon appropriate stimulation. B cells: Types and Functions, NK cells NK cells A specialized subset of T-lymphocytes that exhibit features of innate immunity similar to that of natural killer cells. They are reactive to glycolipids presented in the context of the major histocompatibility complex (MHC) class I-like molecule, CD1D antigen. Lymphocytes: Histology, and CD8+ T cell proliferation and activation.
• Severe combined immunodeficiency Immunodeficiency Chédiak-Higashi Syndrome ( SCID SCID Severe combined immunodeficiency (SCID), also called “bubble boy disease,” is a rare genetic disorder in which the development of functional B and T cells is disturbed due to several genetic mutations that result in reduced or absent immune function. Severe Combined Immunodeficiency (SCID)): the most severe form of primary immunodeficiency Immunodeficiency Chédiak-Higashi Syndrome, SCID SCID Severe combined immunodeficiency (SCID), also called “bubble boy disease,” is a rare genetic disorder in which the development of functional B and T cells is disturbed due to several genetic mutations that result in reduced or absent immune function. Severe Combined Immunodeficiency (SCID) is a genetic disorder that involves defective antibody response due to either direct involvement with B lymphocytes B lymphocytes Lymphoid cells concerned with humoral immunity. They are short-lived cells resembling bursa-derived lymphocytes of birds in their production of immunoglobulin upon appropriate stimulation. B cells: Types and Functions or through improper B-lymphocyte activation due to non-functional T-helper cells. Presents as severe and recurrent opportunistic infections Infections Invasion of the host organism by microorganisms or their toxins or by parasites that can cause pathological conditions or diseases. Chronic Granulomatous Disease and is diagnosed through quantitative PCR Quantitative PCR Methods used for detecting the amplified DNA products from the polymerase chain reaction as they accumulate instead of at the end of the reaction. Polymerase Chain Reaction (PCR) and flow Flow Blood flows through the heart, arteries, capillaries, and veins in a closed, continuous circuit. Flow is the movement of volume per unit of time. Flow is affected by the pressure gradient and the resistance fluid encounters between 2 points. Vascular resistance is the opposition to flow, which is caused primarily by blood friction against vessel walls. Vascular Resistance, Flow, and Mean Arterial Pressure cytometry
• Ataxia Ataxia Impairment of the ability to perform smoothly coordinated voluntary movements. This condition may affect the limbs, trunk, eyes, pharynx, larynx, and other structures. Ataxia may result from impaired sensory or motor function. Sensory ataxia may result from posterior column injury or peripheral nerve diseases. Motor ataxia may be associated with cerebellar diseases; cerebral cortex diseases; thalamic diseases; basal ganglia diseases; injury to the red nucleus; and other conditions. Ataxia-telangiectasia telangiectasia Telangiectasia Permanent dilation of preexisting blood vessels creating small focal red lesions, most commonly in the skin or mucous membranes. It is characterized by the prominence of skin blood vessels, such as vascular spiders. Chronic Venous Insufficiency: a rare, autosomal recessive Autosomal recessive Autosomal inheritance, both dominant and recessive, refers to the transmission of genes from the 22 autosomal chromosomes. Autosomal recessive diseases are only expressed when 2 copies of the recessive allele are inherited. Autosomal Recessive and Autosomal Dominant Inheritance disorder characterized by the association of severe combined immunodeficiency Immunodeficiency Chédiak-Higashi Syndrome, tumor Tumor Inflammation development, and neurological abnormalities. Presents as gait ataxia Gait ataxia Impairment of the ability to coordinate the movements required for normal ambulation (walking) which may result from impairments of motor function or sensory feedback. This condition may be associated with brain diseases (including cerebellar diseases and basal ganglia diseases); spinal cord diseases; or peripheral nervous system diseases. Friedreich Ataxia, apraxia Apraxia A group of cognitive disorders characterized by the inability to perform previously learned skills that cannot be attributed to deficits of motor or sensory function. The two major subtypes of this condition are ideomotor and ideational apraxia, which refers to loss of the ability to mentally formulate the processes involved with performing an action. For example, dressing apraxia may result from an inability to mentally formulate the act of placing clothes on the body. Apraxias are generally associated with lesions of the dominant parietal lobe and supramarginal gyrus. Cranial Nerve Palsies, abnormal movements, telangiectasia Telangiectasia Permanent dilation of preexisting blood vessels creating small focal red lesions, most commonly in the skin or mucous membranes. It is characterized by the prominence of skin blood vessels, such as vascular spiders. Chronic Venous Insufficiency, recurrent pulmonary infections Recurrent pulmonary infections Selective IgA Deficiency, and a higher risk of lymphoma Lymphoma A general term for various neoplastic diseases of the lymphoid tissue. Imaging of the Mediastinum, leukemia, and gastric carcinoma