The goal of this observational study is to identify progressive changes of quantitative brain and lung imaging, serum and movement-related biomarkers reflecting disease progression in pre-symptomatic infants and very young children (0-5 yo) with a genetic diagnosis of A-T, that could be used in future early-life intervention trials.

1. Participants with A-T

   • Inclusion criteria

     • Genetic diagnosis of Ataxia Telangiectasia
     • Aged under two years old at the time of first recruitment
     • Parents/ guardians able to give informed consent

   • Exclusion criteria

     • Contraindication to MRI
     • Diagnosis of any other neurogenetic disease
     • On approved treatment targeting neurodegeneration in A-T at the time of first recruitment
     • Participating in the trial of novel therapy targeting neurodegeneration in A-T at the time of first recruitment

   NB - co-recruitment to other observational studies or trials is permitted. If a family chooses to enrol their child in an interventional study targeting neurodegeneration, provided that the intervention trial allows co-recruitment, we would like to retain the participant in the BOBCAT study until its conclusion. In this circumstance, the child's data would not be considered as part of the natural history dataset but would instead be used to demonstrate the feasibility of collecting longitudinal quantitative imaging and other biomarker data in people with A-T during infancy and early childhood.

2. Participants without A-T

   • Inclusion criteria

     • Child undergoing general anaesthesia at Nottingham University Hospitals NHS Trust for minor surgical procedures or diagnostic MRI.
     • Aged 0-5 years (to match the age range of participants with A-T throughout the longitudinal study).
     • Parents/ guardians able to give informed consent

   • Exclusion criteria

     • Diagnosis of any neurological or neurodevelopmental disease
     • Diagnosis of any other significant chronic childhood illness
     • On any long-term prescribed treatments

Participants with A-T will be recruited principally via the National Paediatric A-T Clinic based at Nottingham University Hospitals NHS Trust. A second route for recruitment is the A-T Society, a UK charity that provides support and advocacy for people with A-T and their families.

Participants without A-T or other conditions described in the exclusion criteria, will be infants and young children undergoing general anaesthesia at Nottingham University Hospitals NHS Trust for minor surgical procedures (e.g. circumcision, orchidopexy) or diagnostic MRI.