Coexistence of Neurofibromatosis Type 1 and Marfan Syndrome in a 13-Year-Old Boy: A Case Report.

BACKGROUND Neurofibromatosis type 1 (NF1) and Marfan syndrome (MFS) are genetically determined systemic disorders. Their simultaneous occurrence is exceptionally rare, with only a few cases reported in the literature. CASE REPORT A 13-year-old boy was admitted to a cardiology clinic due to mitral and tricuspid valve prolapse. He was tall, with severe scoliosis and distinctive dysmorphic features typical of MFS. More than 20 cafe-au-lait spots, characteristic of NF1, were present on his skin. The family history included NF1 in his twin brother, mother, maternal uncle, and maternal grandmother. The maternal uncle also exhibited phenotypic features of MFS and died at a young age from a suspected ruptured intracranial aneurysm. Genetic testing in our patient revealed an NF1 mutation, as well as a 16p13.11 microduplication that could explain his developmental delay and speech difficulties. The diagnosis of MFS was based on characteristic dysmorphic features and the presence of aortic root dilation, despite negative findings concerning the fibrillin-1 (FBN1) mutation typically associated with MFS. CONCLUSIONS A thorough assessment of physical features is essential to detect atypical phenotypes and recognize potential coexistence of multiple genetic syndromes. This case highlights the clinical importance of systematic cardiac evaluation, given that cardiac abnormalities typical of MFS may be critical for its recognition. Reporting such an unusual coexistence of NF1 and MFS underscores the need for multidisciplinary care to improve long-term outcomes in patients with overlapping genetic disorders.