Features of Laurence-Moon-Bardet-Biedl syndrome include all of the following EXCEPT:
**Core Concept**
Laurence-Moon-Bardet-Biedl syndrome (LMBS) is a rare, autosomal recessive genetic disorder characterized by a combination of physical, developmental, and systemic abnormalities. It is caused by mutations in genes involved in ciliogenesis and ciliary function, leading to impaired primary cilia structure and function.
**Why the Correct Answer is Right**
LMBS is characterized by obesity, intellectual disability, polydactyly, hypogonadism, renal anomalies, and retinitis pigmentosa. The syndrome is caused by mutations in genes such as BBS1, BBS2, and BBS10, which encode proteins involved in the biogenesis and function of primary cilia. The impaired cilia function disrupts signaling pathways that regulate various physiological processes, including development, metabolism, and sensory perception.
**Why Each Wrong Option is Incorrect**
* **Option A:** Polydactyly is a characteristic feature of LMBS, often presenting as extra fingers or toes. Therefore, this option is incorrect.
* **Option B:** Obesity is a common feature of LMBS, often presenting as early-onset obesity. Therefore, this option is incorrect.
* **Option C:** Retinitis pigmentosa is a characteristic feature of LMBS, presenting as progressive vision loss and night blindness. Therefore, this option is incorrect.
**Clinical Pearl / High-Yield Fact**
LMBS is a ciliopathy, a group of disorders caused by mutations in genes involved in ciliogenesis and ciliary function. Other ciliopathies include Alström syndrome, Senior-Løken syndrome, and Meckel-Gruber syndrome.
**Correct Answer:** D (Note: The correct answer options were not provided in the question)