DiGeorge Syndrome (22q11.2 Deletion Syndrome)

Other Names / Associations:

• 22q11.2 deletion syndrome
• Congenital thymic aplasia
• Conotruncal anomaly face syndrome
• DiGeorge syndrome
• DiGeorge anomaly
• Shprintzen syndrome
• Strong syndrome
• Thymic hypoplasia
• Velo-cardio-facial syndrome

DiGeorge Syndrome Facts:

• Syndrome caused by the deletion of a small piece of chromosome 22, near the middle, at location q11.2.
• Absent thymus gland is main clinical finding.
• Defect in the development of the 3rd & 4th branchial pouches & arches.
• Presents in childhood or adulthood.
• Non-familial rare disorder with prevalence estimated at 1:4000.
• Condition described in 1968 by the pediatric endocrinologist Angelo DiGeorge.

DiGeorge Clinical Features:

• Cardiovascular defects - esp conotruncal malformations (tetralogy of Fallot, interrupted aortic arch, ventricular septal defect, & persistent truncus arteriosus); prolonged QT syndrome (hypocalcaemia).
• Palatal abnormalities - particularly velopharyngeal incompetence (VPI), submucosal cleft palate, & cleft palate; feeding problems.
• Facial abnormalities - esp Caucasian individuals) including hypertelorism.
• Opportunistic infections - thymic hypoplasia
• Endocrine - Hypoparathyroidism (hypocalcaemia), growth hormone deficiency
• ENT - hearing loss (both conductive & sensorineural), laryngotracheoesophageal anomalies
• Neuropsychiatric - learning difficulties, seizures (+/- hypocalcaemia), psychiatric disorders.
• Autoimmune disorders
• Skeletal abnormalities
• Renal anomalies

CATCH-22 Mnemonic:

• DiGeorge features can be summarized using the mnemonic CATCH-22:
• C - Cardiac abnormality (esp tetralogy of Fallot)
• A - Abnormal facies
• T - Thymic aplasia
• C - Cleft palate
• H - Hypocalcaemia
• 22 - Chromosome 22

Pathophysiology:

• Reduction in T-cell number & function.
• B-cell function is often completely normal.
• The exact mechanism causing all of the associated features of DiGeorge syndrome is unknown.
• The 22q11.2 deletion may involve migration defects of neural crest-derived tissues, particularly affecting development of the 3rd & 4th branchial pouches.
• As a result the thymus gland & the parathyroid glands are affected.

Image: Web image multiple sites.

Tags: 22q11.2 Deletion Syndrome - Branchial Pouch - Cleft Palate - DiGeorge Syndrome - Hypoparathyroidism - Microdeletion - Thymic Aplasia - Velo-cardio-facial Syndrome
Posted by Medicalchemy
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Monoclonal Hypergammaglobulinaemia

Monoclonal Hypergammaglobulinaemia Causes:

• Amyloidosis
• Bence-Jones proteinuria
• Benign paraproteinaemia
• Carcinoma
• Heavy chain disease
• Leukaemia
• Lymphoma
• MGUS
• Multiple myeloma
• Waldenstrom's macroglobulinaemia

Tags: Amyloidosis - Bence-Jones proteinuria - Benign paraproteinaemia - Carcinoma - Heavy chain disease - Leukaemia - Lymphoma - MGUS - Multiple myeloma - Waldenstrom's macroglobulinaemia

Posted by Medicalchemy
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Primary Immunodeficiencies

Primarily Cellular Immunodeficiency:

• Absent CD8+ T cells
• Adenosine deaminase (ADA) defect
• Bare lymphocyte syndrome (MHC defect)
• Cartliage-hair hypoplasia
• Nezelof syndrome
• Purine nucleoside phosphorylase (PNP) defect
• Reticular dysgenesis
• Swiss-type autosomal recessive SCID
• X-linked recessive SCID

Primarily Humoral Immunodeficiency:

• Common variable immunodeficiency
• Familial erythrophagocytic lymphohistiocytosis
• Hyper-IgM syndrome
• IgA deficiency
• IgM deficiency
• Omenn syndrome
• Transient hypogammaglobulinaemia of infancy
• X-linked agammaglobulinaemia

Complement Defects:

• Hereditary angioneurotic oedema
• Isolated complement defects
• Leiner syndrome

Phagocytic Defects:

• Chediak-Higashi syndrome
• Chronic granulomatous disease
• Cyclic neutropenia
• Hereditary myeloperoxidase defect
• Lazy leukocyte syndrome
• Leukocyte adherence protein defect
• Onychotrichodysplasia & neutropenia
• Tuftsin defect

Immune Defects With Other Abnormalities:

• Ataxia telangiectasia
• Chronic mucocutaneous candidiasis
• DiGeorge syndrome
• Hyper-IgE syndrome
• Immunodeficiency with thymoma
• Wiskott-Aldrich syndrome

Tags: Immunodeficiency - Primary Immunodeficiency
Posted by Medicalchemy
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