These results provide further evidence of an association between DRD5 and cervical dystonia, supporting the involvement of the dopamine pathway in the pathogenesis of CD.
Our patient and three other reported carriers of non-c.907_909delGAG-mutations within the first three exons of TOR1A showed similar phenotypes of adult-onset focal or segmental cervical dystonia.
We studied seven subjects with ID: all had cervical dystonia as their main symptom (one patient also had spasmodic dysphonia and two patients had concurrent generalized dystonia, both DYT1-negative).
Analysis of 83 published series including 5,057 patients indicated significant differences in the mean age at onset of five phenotypes of PTD (mean age at onset; 95% CI): DYT1 dystonia (11.3 years; 10.3 to 12.2), writer's cramp (38.4; 36.9 to 39.9), CD (40.8; 40.3 to 41.3), spasmodic dysphonia (43.0; 42.2 to 43.9), and blepharospasm-oromandibular dystonia (55.7; 55.1 to 56.4).
Recent genetic studies suggest that the Val66Met polymorphism of the BDNF gene is a genetic modifier in cranial-cervical dystonia in Caucasians.However, the finding is not consistent.
We explored the influence of the Val66Met SNP of the BDNF gene on the risk of cranial and cervical dystonia in a cohort of 156 Italian patients and 170 age- and gender-matched healthy control subjects drawn from the same population.
Adult-onset idiopathic focal dystonia affecting specific parts of the body, such as the eye (blepharospasm), neck (cervical dystonia), and hand (writer's cramp), is mostly associated with the DYT7 locus, which was originally mapped to chromosome 18p by genomewide linkage analysis in a large family showing autosomal dominant inheritance.
Mutations in GNAL have been associated with adult-onset cranio-cervical dystonia, but a limited number of cases have been reported so far and the clinical spectrum associated with this gene still needs to be fully characterized.
In addition, splicing variants of CIZ1 mRNA is associated with a variety of cancers and Alzheimer's disease, and mutations of the CIZ1 gene lead to cervical dystonia.
One novel likely pathogenic substitution (c.1061T>C; p.Val354Ala) in GNAL was detected in a sporadic cervical dystonia patient (mutation frequency: 0.4%).