An atypical presentation of ataxia telangiectasia in a school-aged boy secondary to an intronic mutation

Background: Ataxia telangiectasia typically presents in early pre-school years with progressive cerebellar ataxia and oculocutaneous telangiectasias. Referral to Immunology is often made after diagnosis has been established, as patients are prone to both humoral and cellular immune abnormalities. Case presentation: We herein report a 10-year old boy, previously undiagnosed, who presented with recurrent pneumonias. On history, frequent falls and speech difficulty were reported, with no telangiectasias on exam. Screening with alpha-fetoprotein was abnormal, followed by ATM gene sequencing, showing a homozygous intronic mutation. Over the next 3 years the patient deteriorated neurologically, and developed appreciable telangiectasias. Conclusion: A review of the literature demonstrates that intronic/splicing mutations may result in atypical ataxia telangiectasia phenotypes and delayed presentations. We advise immunologists to have a high index of suspicion for ataxia telangiectasia when assessing a patient with immunodeficiency and neurologic regression, regardless of age, and even in the absence of telangiectasias. Statement of novelty: We present a case of phenotypically atypical (“leaky”) ataxia telangiectasia resulting from a novel homozygous splice-site mutation in the ATM gene. Given high reported prevalence of intronic and splice-site mutations in ATM, we recommend full gene sequencing in patients suspected to have ataxia telangiectasia, especially in those with late onset or unusual manifestations.