**Question:** Association of deafness & nephritis is seen in

A. Glycogen Storage Disease Type II (Mendelian Inheritance in Man #510500)
B. Usher Syndrome (MIM #276900)
C. Meniere's Disease (MIM #121000)
D. Sjogren-Larsson Syndrome (MIM #270250)

**Correct Answer:** B. Usher Syndrome (MIM #276900)

**Core Concept:** Usher syndrome is a rare genetic disorder characterized by the coexistence of sensorineural hearing loss and vestibular dysfunction. This condition is primarily associated with the combined effects of auditory and visual impairments.

**Why the Correct Answer is Right:** Usher syndrome is a result of mutations in various genes, such as USH1, USH2, and USH3. These genes are involved in the development and maintenance of the inner ear and retinal photoreceptor cells. The coexistence of hearing loss and nephritis in this question is incorrect, as nephritis is not a typical symptom of Usher syndrome.

**Why Each Wrong Option is Incorrect:**

A. Glycogen Storage Disease Type II (MIM #510500) is a rare disorder caused by the deficiency of the enzyme phosphorylase kinase. It primarily affects the liver and muscles, leading to glycogen accumulation. Nephritis is not a typical feature of this condition.

B. Usher Syndrome (MIM #276900) as mentioned above.
C. Meniere's Disease (MIM #121000) is characterized by episodes of vertigo, hearing loss, and tinnitus. Nephritis is not a typical feature of Meniere's disease.
D. Sjogren-Larsson Syndrome (MIM #270150) is a genetic disorder caused by mutations in the ALDH3A2 gene, leading to fatty aldehyde dehydrogenase deficiency. This condition primarily affects the skin, eyes, and nervous system, and nephritis is not a typical feature of Sjogren-Larsson Syndrome.

**Clinical Pearl:**

Usher syndrome is a crucial diagnosis to consider in patients presenting with sensorineural hearing loss and vestibular dysfunction, especially when the patient is young, as it leads to an early-onset sensorineural hearing loss and vestibular dysfunction. Inheritance patterns for each type of Usher syndrome are different, with Type I being autosomal recessive, Type II being autosomal dominant, and Type III being X-linked recessive.

This question likely aims to test your knowledge of the different types of Usher syndrome and their inheritance patterns, as well as your understanding of the clinical features of each type.

**Why Each Wrong Option is Incorrect:**

A. Glycogen Storage Disease Type II (MIM #510500) is caused by the deficiency of glycogen phosphorylase kinase and affects the liver, muscles, and brain. Ne