<prompt> Ataxia telangiectasia is characterised by all of the following exceptChronic sinopulmonary diseaseDecreased level of αfetoproteinChromosomal breakageIgA deficiency  <response>: Persistence of very high levels of oncofetal proteins, including alpha-fetoproteins and carcinoembryonic antigens is of diagnostic value - HarrisonAtaxia telangiectasia Ataxia Telangiectasia AT is an autosomal recessive disorder.It is due to mutation of AT gene located on chromosome 11.There is defective DNA repair that results in multiple chromosomal breaks.Clinical manifestationsPresent in the first decade of life.Feature are : -Oculocutaneous telengiectasiaNeurological Ataxia, dysarthria, extensor plantar response, myoclonic jerks, are flexia, distal sensory deficit.Immunodeficiency Thymic hypoplasia with cellular and humoral IgA and IgG2 immunodeficiency.Recurrent pulmonary infectionsEndocrine disorders Type I DMPremature ageingMalignancies Lymphoma, Hodgkins disease, acute T cell leukemia, breast cancer.α-feto protein and carcino-embryonic antigen are increased 