Sequential central retinal artery occlusion in two brothers: a fight to prevent blindness.

Importance: Central retinal artery occlusion (CRAO) is typically associated with older patients with cardiovascular risk factors. However, its occurrence in younger patients without these risk factors suggests the need to explore rare genetic conditions. Identifying genetic disorders like adenosine deaminase 2 deficiency (DADA2), a vasculitic disease, can be critical in such cases to prevent further complications.

Objective: To report the challenging diagnosis of two cases of CRAO in brothers under the age of 40, leading to the diagnosis of DADA2, a rare genetic vasculitic disorder.

Results: A 34-year-old man and his 32-year-old brother, both without significant medical histories, presented with CRAO eight years apart. Extensive diagnostic evaluations, including blood tests, imaging, and autoimmunity panels, failed to identify common causes. Progressive neurological symptoms in the older brother and the similar presentation in his sibling led to further investigation, including genetic testing. A homozygous mutation c.752C > T p.(Pro251Leu) in the CECR1 gene confirmed the diagnosis of DADA2 in both brothers.

Conclusion: These cases underscore the importance of considering genetic disorders like DADA2 in young patients presenting with unexplained vascular occlusions. DADA2, characterized by vasculitis, immune dysregulation, and hematologic disorders, can manifest variably, complicating early diagnosis. Effective treatment with TNF inhibitors can prevent further vision loss and mitigate systemic complications. To our knowledge, these are the first reported cases of DADA2 with CRAO as the initial manifestation without prior clinical findings.