**Core Concept**
Juvenile myoclonic epilepsy (JME) is a subtype of generalized epilepsy characterized by myoclonic seizures, generalized tonic-clonic seizures, and sometimes absence seizures. The disorder is associated with mutations in genes involved in the regulation of neuronal excitability and synaptic transmission.

**Why the Correct Answer is Right**
The gene involved in JME is **SCN1A**, which encodes the alpha subunit of the voltage-gated sodium channel NaV1.1. Mutations in SCN1A disrupt the normal functioning of the sodium channel, leading to hyperexcitability of neurons and an increased propensity for seizures. SCN1A mutations are responsible for a significant proportion of JME cases, as well as other forms of generalized epilepsy.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because it is not the correct gene associated with JME. While other genes like GABRA1 and GABRD are involved in epilepsy, they are not specifically linked to JME.

**Option B:** This option is incorrect because it is not the correct gene associated with JME. Although GRIN2A mutations are associated with a form of generalized epilepsy, they are not specifically linked to JME.

**Option C:** This option is incorrect because it is not the correct gene associated with JME. While KCNQ2 mutations are associated with benign familial neonatal seizures, they are not specifically linked to JME.

**Clinical Pearl / High-Yield Fact**
Mutations in SCN1A are not only associated with JME but also with Dravet syndrome, a severe form of epilepsy characterized by febrile seizures, developmental delay, and other neurological abnormalities.

**Correct Answer: SCN1A**