Clinical Scenario:
A 7-year-old boy is evaluated for recurrent chest infections since early childhood. He has required several hospital admissions for pneumonia. He now presents with progressive breathlessness and cyanosis and is found to have pulmonary hypertension.
On examination, there are fine reddish, branching vessels over the sclera near the inner and outer canthi. His parents also report that he has recently become unsteady while walking and frequently loses his balance.
Which of the following is the most likely diagnosis?
A. Cystic fibrosis
B. Ataxia-telangiectasia
C. Chronic granulomatous disease
D. Primary ciliary dyskinesia
E. Common variable immunodeficiency
Correct answer & Explanation:
Correct answer: B. Ataxia-telangiectasia
Explanation
Ataxia-telangiectasia (A-T) is an autosomal recessive disorder caused by pathogenic variants in the ATM gene, resulting in defective DNA damage response and chromosomal instability.
The classic clinical combination is:
- Progressive cerebellar ataxia — typically becoming evident in early childhood
- Oculocutaneous telangiectasia — particularly visible on the conjunctiva
- Recurrent sinopulmonary infections due to combined immunodeficiency
The reddish branching vessels over the conjunctiva in this child represent telangiectasia and are an important diagnostic clue.
Recurrent respiratory infections may lead to chronic lung disease and bronchiectasis, which can contribute to pulmonary hypertension and, in advanced disease, hypoxemia and cyanosis.
Other features that may occur include elevated alpha-fetoprotein (AFP), growth retardation, dysarthria, premature aging changes and increased risk of malignancy, particularly lymphoid malignancies.
Exam pearl:
Recurrent respiratory infections + progressive ataxia + conjunctival telangiectasia = ataxia-telangiectasia.
Reference:
Gatti R, Perlman S. Ataxia-Telangiectasia. GeneReviews®. University of Washington, Seattle. Updated 2024.
