ATAXIA TELANGIECTASIA 

Genetic map:

• Gene involved – ATM gene on chromosome 11 which encodes Atm protein kinase, a member of phosphatidyl   inositol 3-kinase family
• only phacomatotic hereditary condition transmitted in the autosomal recessive mode, where combined immunodeficiency is associated with cerebellar ataxia, telangiectasia, ovarian dysgenesis & chromosomal abnormalities. 

Clinical and Histologic features:

• Presents in the first decade of life with progressive telangiectatic lesions and ataxia & chorio-athetoid movements associated with deficits in cerebellar function and nystagmus
• Truncal and limb ataxia, dysarthria, extensor plantar responses, myoclonic jerks, areflexia, distal sensory deficits
• Thymic hypoplasia, premature aging, Type 1 DM
•  ↑ incidence of recurrent pulmonary infections, lymphomas, Hodgkin’s disease, acute T cell leukemia, breast cancer
•  Most striking neuropathologic changes: loss of Purkinje, granule and basket cells in the cerebellar cortex and neurons in the deep cerebellar nuclei

Complication:

 Death occurs due to sinopulmonary infection early in life , or malignancy in 2nd  or 3rd decade.

Immunological features :

• May affect T&B cells
• IgA, IgE and IgG2 deficiency.
• T cell function is variably depressed.
• CMI is also defective resulting in impairment of delayed hypersensitivity & graft rejection.  

Treatment : Transfer factor therapy & fetal thymus transplants.

 Exam Question

ATAXIA TELANGIECTASIA

• Gene involved – ATM gene on chromosome 11 which encodes Atm protein kinase, a member of hosphatidyl   inositol 3-kinase family
• only phacomatotic hereditary condition transmitted in the autosomal recessive mode, where combined immunodeficiency is associated with cerebellar ataxia, telangiectasia, ovarian dysgenesis & chromosomal abnormalities. 
• Presents in the first decade of life with progressive telangiectatic lesions and ataxia & chorio-athetoid movements associated with deficits in cerebellar function and nystagmus