Harlequin skin change is seen due to mutation of which gene?
**Core Concept**
Harlequin skin change is a rare condition characterized by a sudden onset of a unique skin pattern, typically in a newborn. This phenomenon is associated with a genetic mutation affecting ion channels in the skin, leading to abnormal electrical activity.
**Why the Correct Answer is Right**
The correct answer is related to the genetic mutation of the _SCN9A_ gene, which encodes for the NaV1.7 sodium channel. This channel plays a crucial role in the transmission of nerve impulses in the skin. Mutations in the _SCN9A_ gene can lead to altered sodium channel function, resulting in abnormal electrical activity and the characteristic skin pattern seen in Harlequin ichthyosis.
**Why Each Wrong Option is Incorrect**
* **Option A:** While mutations in other genes can cause skin disorders, the specific condition of Harlequin skin change is primarily associated with the _SCN9A_ gene.
* **Option B:** This option is incorrect as it refers to a different genetic mutation, which is not linked to Harlequin skin change.
* **Option C:** This option is also incorrect as it refers to a different gene, which is not associated with the condition.
**Clinical Pearl / High-Yield Fact**
Harlequin ichthyosis is often associated with other systemic complications, including ectodermal dysplasias, and should be managed in a multidisciplinary setting to address these additional concerns.
**Correct Answer:** C. SCN9A