Segawa disease is a rare dystonia due to autosomal dominant guanosine triphosphate cyclohydrolase I (adGTPCH) deficiency, affecting dopamine and serotonin biosynthesis. Recently, the clinical phenotype was expanded to include psychiatric manifestations, such as depression, anxiety, obsessive-compulsive disorder, and sleep disturbances. Although cognitive and neuropsychiatric symptoms may be attributable to dopamine deficiency in the prefrontal cortex and frontostriatal circuitry, intelligence is considered normal in Segawa disease. Our aim was to investigate neuropsychiatric symptoms and intelligence quotients (IQ) in a series of individuals with adGTPCH deficiency. The assessment included a structured clinical interview following the DSM-IV-TR's guidelines, Beck's Depression Inventory, the State-Trait Anxiety Inventory, the Maudsley Obsessive-Compulsive Questionnaire, the Barratt Impulsiveness Scale-11 (BIS-11), the Oviedo Sleep Questionnaire, the Pittsburgh Sleep Quality Index, and the Wechsler Adult Intelligence Scale-Third Edition. Equivalent tests were applied to pediatric patients as appropriate for their age group. Fourteen patients with adGTPCH deficiency were evaluated (seven adult and seven pediatric patients). Depression, anxiety, and obsessive-compulsive symptoms were not more common than expected in the general population. However, the seven adults showed impulsivity in the BIS-11; nine individuals had an IQ in the range of borderline intellectual functioning to mild mental retardation, and sleep disturbances were found in four individuals. We found no differences between these results and the motor impairment. In conclusion, our findings would suggest that cognitive impairment, and impulsivity in adults, may be associated with Segawa disease.

Autosomal dominant guanosine triphosphate cyclohydrolase I deficiency is an inborn error of neurotransmitter metabolism, with a prevalence of 0.5 per million, caused by mutations/deletions in the GCH1 gene. The finding of the mutation Q89X in the GCH1 gene in 23 patients from two pedigrees in an area inhabited by a population of 800,000 prompted us to consider that our cohort may have descended from a single founder. Twelve Q89X mutation-positive cases belonging to two families and 100 unrelated control subjects from the same geographical region were studied. Six microsatellite markers located near GCH1 were analyzed to validate a possible mutation-related founder haplotype. Haplotype analysis revealed two different haplotypes for six microsatellite markers that segregated with the Q89X mutation. A common haplotype in 10 out of 12 mutation carriers studied was identified. Two subjects carried a second haplotype, most probably because of a recombination event. However, at least 186 different haplotypes were established in the control subjects. In contrast with the frequencies of 83.3% and 16.7%, respectively, found for both mutation-segregating haplotypes, the frequency of none of the control haplotypes exceeded 1.5%. Dystonia was the most frequent symptom in our series, and parkinsonism was present in five patients. The large number of Q89X mutation carriers in our community is because of a founder effect. The same mutation in GCH1 causes a wide phenotypic spectrum of clinical variability occurring in this population of affected patients.

This study reveals the existence of oxidative stress (reactive oxygen species (ROS)) in non-nervous organs and tissues in multiple sclerosis (MS) by means of a model of experimental autoimmune encephalomyelitis (EAE) in rats. This model reproduces a similar situation to MS, as well as its relationship with intestinal microbiota starting from the changes in bacterial lipopolysaccharide levels (LPS) in the outer wall of the gram-negative bacteria. Finally, the administration of extra-virgin olive oil (EVOO), hydroxytirosol (HT), and oleic acid (OA) exert beneficial effects. Twenty-five Dark Agouti two-month-old male rats, weighing around 190 g, were distributed into the following groups: Control, EAE (experimental autoimmune encephalomyelitis group), EAE + EVOO, EAE + HT, and EAE + OA. The glutathione redox system with the EAE was measured in heart, kidney, liver, and small and large intestines. The LPS and the correlation with oxidative stress in the small and large intestines were also investigated. The results showed that (1) the oxidative damage in the EAE model affects non-nervous organs and tissues; (2) The LPS is related to inflammatory phenomena and oxidative stress in the intestinal tissue and in other organs; (3) The administration of EVOO, HT, and OA reduces the LPS levels at the same time as minimizing the oxidative damage; (4) EVOO, HT, and OA improve the disease’s clinical score; and (5) on balance, EVOO offers a better neuroprotective effect.

We did not find any evidence supporting the association of NALCN with cervical dystonia, indicating that this gene is not implicated in the pathogenesis of this disorder in our cervical dystonia population.

We did not find any evidence supporting the association of the BDNF Val66Met polymorphism with primary dystonia.