A child with hypogonadism, mental retardation, and retinitis pigmentosa has which syndrome?

The features described in the question—hypogonadism, mental retardation, and retinitis pigmentosa—are all characteristic manifestations of Bardet-Biedl syndrome. This condition is a genetic disorder that is part of the group of ciliopathies, which result from defects in cilia function. The syndrome typically presents with a combination of symptoms including obesity, polydactyly, renal anomalies, and varying degrees of intellectual disability, alongside retinitis pigmentosa, which is a progressive eye disease that leads to vision loss.

The presence of hypogonadism in Bardet-Biedl syndrome is particularly relevant, as individuals with this condition may exhibit primary gonadal insufficiency due to the effects of the syndrome on the endocrine system. Additionally, mental retardation is a noted aspect of the cognitive profile for many affected individuals.

In contrast, Smith-Lemli-Opitz syndrome is primarily characterized by developmental delays and varying physical malformations but does not typically include retinitis pigmentosa or the other specific features mentioned in this context. Friedreich's ataxia is primarily a degenerative disorder affecting the spinal cord and peripheral nerves, and while it can have cognitive impacts, it is not associated with the specific combination of symptoms listed. Marfan syndrome is