Ataxia Telangiectasia Presenting as Cervical Dystonia

Area of Science:

• Genetics and Molecular Biology
• Neuroscience
• Oncology

Background:

• The Ataxia Telangiectasia Mutant (ATM) protein functions as a crucial sensor and signal transducer for DNA damage, initiating cellular responses like cell cycle arrest and apoptosis.
• Classic Ataxia-Telangiectasia (A-T) is typically linked to homozygous mutations in the ATM gene, leading to a complete loss of its kinase activity.
• Variant A-T cases may present with residual ATM kinase activity, indicating a spectrum of disease severity associated with ATM gene mutations.

Observation:

• A six-year-old male patient presented with abnormal neck movements as the primary symptom.
• ATM gene analysis revealed a rare homozygous nonsense mutation (p.Arg23Ter) in exon 2, causing premature protein truncation.
• This specific mutation resulted in a complete loss of ATM kinase function.

Findings:

• The study identified a novel homozygous nonsense mutation in the ATM gene in a pediatric patient with an unusual presentation of classic A-T.
• The identified mutation led to a premature stop codon and a severely truncated ATM protein, consistent with loss of function.
• The patient's clinical presentation, despite the severe mutation, highlights the complexity of genotype-phenotype correlations in A-T.

Implications:

• This case underscores the importance of considering genetic testing, including pedigree analysis, for pediatric patients presenting with movement disorders, even with atypical symptoms.
• In resource-limited settings, leveraging web-based mutation prediction tools can aid in assessing the pathogenicity of novel ATM variants when kinase assays are unavailable.
• Long-term follow-up is essential for patients diagnosed with A-T to manage potential long-term health complications and monitor disease progression.