What is a distinguishing feature of homocystinuria compared to Marfan syndrome?

Homocystinuria is a metabolic disorder caused by a deficiency of cystathionine beta-synthase, leading to an accumulation of homocysteine and related compounds in the body. One of the characteristic features of homocystinuria is the presence of intellectual disability, which can vary in severity among affected individuals. Cognitive impairment results from toxic effects related to the accumulation of homocysteine, and it distinguishes this condition from Marfan syndrome, where individuals typically possess normal cognitive function despite having other systemic manifestations such as connective tissue abnormalities.

In contrast, Marfan syndrome primarily affects the connective tissues and is characterized by features like tall stature, arachnodactyly, and cardiovascular anomalies such as aortic root dilation. However, patients with Marfan syndrome do not typically have intellectual disabilities.

Thus, the significant difference in cognitive function between these two disorders highlights why intellectual disability is a distinguishing feature of homocystinuria compared to Marfan syndrome.