A nurse is assessing a 10-year-old child suspected of having Marfan syndrome. Which assessment finding would be most characteristic of this genetic connective tissue disorder?

Marfan syndrome is characterized by a tall, thin build with disproportionately long arms and fingers (arachnodactyly), which is the most distinctive skeletal feature. Other options describe findings not typical of Marfan syndrome.

Understanding Marfan Syndrome Skeletal Manifestations

Marfan syndrome (MFS) is an autosomal dominant connective tissue disorder caused by pathogenic variants in the FBN1 gene, which encodes fibrillin-1, a critical structural protein [2,3]. The multisystem nature of this condition means that a nurse's assessment must integrate findings across the cardiovascular, ocular, and skeletal systems. In the context of a pediatric assessment, the skeletal features are often the most immediately observable clues.

The most characteristic skeletal presentation is a tall, thin body habitus with disproportionately long extremities, a condition described as dolichostenomelia. This disproportionate growth is a direct result of the defective fibrillin-1 protein's impact on the regulation of transforming growth factor-beta (TGF-β) and the structural integrity of the extracellular matrix in bone and periosteum ^[2]. The excessive linear growth described in the case of the 13.5-year-old boy is a classic example of this manifestation ^[1]. This finding is coupled with arachnodactyly, which refers to abnormally long and slender fingers and toes.

The other options presented are not consistent with the typical Marfan syndrome phenotype. A short stature with a broad chest and shortened limbs is characteristic of skeletal dysplasias like achondroplasia, not the excessive long bone growth seen in MFS. While Marfan syndrome can affect bone quality and is associated with a higher risk of osteoporosis and fragility fractures, it does not typically present with primary muscle weakness and delayed motor development ^[2]. Joint involvement in MFS characteristically involves joint hypermobility and laxity, leading to an increased, rather than decreased, range of motion, making joint stiffness an atypical finding. A comprehensive assessment would also prompt the nurse to anticipate cardiovascular monitoring, as severe aortic root dilatation is a life-threatening complication that can manifest even in pediatric patients [1,4].