Background: Marfan syndrome is a potentially fatal inherited autosomal dominant condition impacting the cardiovascular and the skeletal system with an estimated 25% cases caused by sporadic genetic variations. Given the genetic inheritance pattern, an autopsy of probands with Marfan syndrome-associated mortality is critical to establish the phenotypic expression and clinical implications of the particular genetic variant, especially for first-degree relatives. We present the findings of a Marfan syndrome proband decedent presenting with sudden onset abdominal pain and unexplained retroperitoneal abdominal hemorrhage. Methods: An autopsy was performed to inform the blood relatives of the phenotypic expression and penetrance of the potentially heritable condition. A clinical laboratory improvement amendment (CLIA)-certified clinical grade genetic sequencing was performed to identify pathogenic variants in genes associated with aortopathy. Results: The autopsy showed intra-abdominal and retroperitoneal hemorrhage due to infarction of the right kidney caused by dissection of the right renal artery. Genetic testing identified a heterozygous pathogenic Conclusions: We report a case of a previously undiagnosed Marfan syndrome death due to a