C62-13 Two Cases of Genetic Defects Causing Diffuse Alveolar Hemorrhage

Abstract Objective Diffuse alveolar hemorrhage (DAH) has a complex etiology, with immune disorders being the most common cause, followed by inflammatory and infectious diseases. Genetic disorders are rare causes of DAH. This study reports two cases of DAH secondary to Rubinstein-Taybi syndrome (RS-TS) and Noonan syndrome (NS). The aim was to summarize the key clinical features of these two patients, particularly those related to DAH. Method This retrospective analysis reviewed clinical data of two pediatric patients with RS-TS and NS forms of DAH admitted to the Department of Pediatrics, First Affiliated Hospital of Guangxi Medical University. All clinical data were obtained from the electronic medical records system, including clinical manifestations, physical examinations, family history, and chest CT scan results. Results Among the two pediatric cases we collected, one child was diagnosed with RS-TS secondary to DAH after whole-exome sequencing revealed a CREBBP gene mutation and abundant hemosiderin-laden macrophages (HLMs) in alveolar lavage fluid (BALF). The other child showed a PTPN11 gene heterozygous mutation through whole-exome sequencing, with HLMs detected in both BALF and gastric fluid, ultimately confirming Noonan syndrome (NS) secondary to DAH. Both patients received combined corticosteroid and hydroxychloroquine therapy, with subsequent follow-up demonstrating good disease control. Conclusions 1. This study is the first to report cases of Noonan syndrome and Rubinstein-Taybi syndrome with secondary DAH, expanding the etiological spectrum of DAH in genetic metabolic disorders; 2. In addition to primary disease management, corticosteroids combined with immunosuppressants and/or hydroxychloroquine are key therapeutic agents for DAH associated with genetic metabolic diseases. This abstract is funded by: None