SNP Shot: Genomic Insights

Essential tremor is a movement disorder characterized by involuntary, rhythmic shaking (tremor), most commonly affecting the hands. Unlike tremors caused by conditions like Parkinson's disease or head injuries, essential tremor typically occurs independently, without other neurological signs. While generally isolated, some experts believe that essential tremor may present with additional symptoms, such as minor balance issues.

The tremors associated with essential tremor usually appear during movement and can manifest during everyday activities like eating, drinking, or writing. They can also occur when muscles work against gravity, such as when holding the hands outstretched. Typically, the tremor is not noticeable when the body is at rest.

Besides the hands and arms, essential tremor can also affect muscles in the trunk, face, head, and neck. The legs and feet are less frequently involved. Head tremors can present as a "yes-yes" or "no-no" motion while sitting or standing. In some individuals, the voice may also be affected, resulting in vocal tremor.

Essential tremor does not reduce life expectancy. However, it can significantly impact fine motor skills needed for tasks like using utensils, writing, shaving, or applying makeup. In severe cases, these and other daily activities can be substantially impaired. Factors like emotional stress, anxiety, fatigue, hunger, caffeine, smoking, or extreme temperatures can exacerbate the symptoms of essential tremor.

Essential tremor can begin at any age but is most prevalent in older adults. Research suggests that individuals with essential tremor might have an increased risk of developing other neurological conditions, including Parkinson's disease, or sensory impairments like hearing loss, particularly if the tremor develops after age 65.

Inheritance:

Essential tremor can be hereditary, passing down through families, but the pattern of inheritance varies. In most families, essential tremor seems to follow an autosomal dominant inheritance pattern. This means only one copy of a mutated gene in each cell is sufficient to cause the condition. However, the specific genes responsible for essential tremor have not yet been identified. In other families, the inheritance pattern is unclear. Essential tremor can also occur in individuals with no family history of the disorder. Some families may have individuals with essential tremor alongside others with different movement disorders, such as dystonia (involuntary muscle tensing). The possible genetic link between essential tremor and other movement disorders is an ongoing area of scientific investigation.