Abstract: Provided herein are antisense oligonucleotides and prophylactic and therapeutic methods featuring such oligonucleotides. These oligonucleotides and methods are useful for treating or preventing ataxia telangiectasia in a subject. Specifically, the disclosure provides antisense nucleobase oligomers each comprising (8-40) nucleobases, wherein at least 90% of said nucleobases or more than (8) consecutive nucleobases of the oligomer are complementary to a nucleic acid sequence in an Ataxia-Telangiectasia Mutated (ATM) allele comprising a mutation associated with aberrant splicing.