Short Telomere Syndrome in a Patient With Unexplained Respiratory Failure and Pneumocystis jirovecii Pneumonia

Short telomere syndromes (STS) are a group of inherited disorders characterized by accelerated telomere shortening, leading to impaired tissue regeneration and multisystem involvement. Although pulmonary fibrosis and bone marrow failure are well-recognized manifestations, atypical presentations can delay diagnosis. We report a case of a patient presenting with unexplained respiratory failure complicated by Pneumocystis jirovecii pneumonia (PJP), ultimately found to have an underlying short telomere syndrome. The patient exhibited progressive dyspnea, hypoxemia, and diffuse interstitial changes on imaging, without a prior history of immunodeficiency. Microbiological evaluation confirmed PJP, raising suspicion of an occult immune dysfunction. Further investigation revealed cytopenias and markedly shortened telomere length, supporting the diagnosis of STS. The clinical course highlighted the interplay between telomere biology, immune impairment, and susceptibility to opportunistic infections. This case underscores the importance of considering telomere disorders in patients with unexplained respiratory failure, especially when accompanied by atypical infections or hematologic abnormalities. Early recognition is essential for guiding management, genetic counseling, and prognostic assessment.