User:Sujinlim86/sandbox

I want to update the cause section of spasmodic dysphonia. The exact cause of SD is still unknown, but recent studies have identified some possible pathogenic factors including epidemiological risk factors, genetic factors and neurologic factors. As the current article already explains neurologic factors, I will focus on the rest two (risk factors and genetic factors).

Cause
Although the exact cause of spasmodic dysphonia (i.e., laryngeal dystonia) is still unknown, epidemiological, genetic and neurological pathogenic factors have been proposed in recent research.

Epidemiological risk factors identified in several large cohort studies include : It has not been established whether these factors directly impact the development of spasmodic dysphonia (SD), however these factors could be used to identify possible and/or at-risk patients.
 * Being female
 * Being middle aged
 * Having a family history of neurological diseases (e.g., tremor, dystonia, meningitis and other neurological diseases)
 * Stressful events
 * Upper respiratory tract infections
 * Sinus and throat illnesses
 * Heavy voice use
 * Cervical dystonia
 * Childhood measles or mumps
 * Pregnancy and parturition

Researchers have also explored the possibility of a genetic component to SD. Three genes have been identified that may be related to the development of focal or segmental dystonia: TUBB4A, THAP1 and TOR1A genes. However, a recent study that examined the mutation of these three genes in 86 SD patients found that only 2.3% of the patients had novel/rare variants in THAP1 but none in TUBB4A and TOR1A. Evidence of a genetic contribution for dystonia involving the larynx is still weak and more research is needed in order to establish a causal relationship between SD and specific genes.