Ataxia-telangiectasia (A-T) is a rare hereditary disorder that affects multiple organ systems.


Genetic defect: translocations in 14q11-12, 14q32, 7q35, and 7p14, resulting in a A-T mutated protein (ATM)


Inheritance: autosomal recessive


Clinical findings:

(1) progressive cerebellar ataxia, usually with an onset of 1-3 year of age

(2) ocular apraxia (inability to follow an object across the visual fields), usually with an onset after 3 years of age

(3) progressive dysarthria (slurred speech)

(4) oculocutaneous telangiectasias, usually appearing later during childhood

(4a) conjunctival

(4b) over ears

(4c) over the bridge of the nose

(4d) in the antecubital fossa and/or the popliteal fossa

(4e) occasionally generalized

(5) radiation hypersensitivity

(6) primary humoral and cellular immunodeficiency

(6a) frequent respiratory and sinonasal bacterial infections

(6b) IgA is frequently absent with other immunoglobulins variable in amount

(6c) total T cells and T helper cells are decreased, while T suppressor cells may be normal or increased

(6d) anergy to skin allergy testing

(7) predisposition to cancers (breast cancer, lymphoma, leukemia, other cancers)

(8) family history in siblings

(9) variable endocrine abnormalities

(9a) absent or hypoplastic ovaries in females

(9b) reduced fertility in males

(9c) diabetes mellitus

(10) variable hypertrichosis

(11) premature aging

(12) decreased lifespan


Imaging studies:

(1) MRI shows a small, dystrophic cerebellum


Laboratory findings:

(1) Serum alpha-fetoprotein (AFP) is almost always elevated.

(2) Absent or greatly reduced A-TM (A-T mutated) protein.


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