Supplemental Material for: A case report of Pearson Syndrome: Addressing the Complexities Beyond Anemia

This fatal condition requires a high degree of clinical suspicion due to its phenotypic heterogeneity.</p><p dir="ltr">Case presentation: We present the case of an8-month-old infant with sideroblastic anemia and thrombocytopenia, initially showing a negative whole-exome sequencing (WES) result from peripheral blood.

Bone marrow reexamination revealed additional findings, including vacuolization of erythroid and myeloid precursors. With clinical suspicion of Pearson syndrome, analysis of the mitochondrial genome in WES data identified a novel 4.9Kb mitochondrial DNA deletion (m.8482_13477del4996) covering the COX3, ND3, ND4, ND5, ATP6, and ATP8 genes, with subsequent multisystem involvement confirming the diagnosis. </p><p dir="ltr">Conclusion: This case underscores the importance of integrating laboratory findings with genetic testing, as focused analysis of the mitochondrial genome in cases of sideroblastic anemia in bone marrow can give a definitive diagnosis of Pearson syndrome.</p>