Xinhua Wan

Clinical and genetic evaluation of DYT1 and DYT6 primary dystonia in China

Background:  Dystonia is defined as the presence of sustained involuntary muscle contractions, often leading to abnormal posture and movement. DYT1 is caused by a mutation in the TOR1A gene, whilst mutations in THAP1 gene have been identified as responsible for DYT6. The relative frequency and phenotype differences between DYT1 and DYT6 amongst Chinese primary dystonia patients have not been well‐characterized.

Mutation screening of GNAL gene in patients with primary dystonia from Northeast China.

BACKGROUND Mutations in GNAL have recently been identified as responsible for primary dystonia, however, GNAL mutations in Chinese patients with primary dystonia are not well characterized. PATIENTS AND METHODS Fifty-nine unrelated patients with cervical onset or cervical involved primary dystonia and 120 neurologically normal controls from Northeast China without mutations of TOR1A and THAP1 were all screened for mutation of GNAL gene. RESULTS One subject with adult-onset generalized dystonia was found have a novel nonsense GNAL mutation (c.284C>T, p.Ser95X). Another subject with adult-onset cervical dystonia was found harbor the c.932-7T>G tentative splice site mutation. Although another seventeen sequence variants were identified in both patients and controls, no disease association was found among these sequence variants. CONCLUSIONS Mutations in GNAL gene can cause adult-onset primary dystonia in Chinese patients, and the mutation frequency is 3.4% in cervical onset or cervical involved primary dystonia. This paper identifies the first case of GNAL dystonia in the Chinese population.

No mutations in CIZ1 in twelve adult‐onset primary cervical dystonia families

Service de Neurologie, Centre Expert Parkinson et Centre Maladie Rare Atrophie Multisyst ematis ee Centre Hospitalier Universitaire de Bordeaux Pessac, France Institut des Maladies Neurod eg en eratives Unit e Mixte de Recherche (UMR) 5293 University de Bordeaux Bordeaux, France Le Centre National de la Recherche Scientifique Institut des Maladies Neurod eg en eratives UMR 5293, Bordeaux, France Institut National de la Sant e et de la Recherche M eedicale (INSERM) Unit e 612, Orsay, France Institut Curie-Recherche, Orsay, France Institut Curie, Department of Tumour Biology Paris, France Institut Curie, INSERM Unit e 830, Paris, France Universit e Paris Descartes, Sorbonne Paris Cit e Paris, France References

Mutations in ANO3 and GNAL gene in thirty‐three isolated dystonia families

Dystonia is a movement disorder characterized by sustained or intermittent muscle contractions, abnormal movements, postures, or both. Recently, ANO3 and GNAL genes have been identified to be causative genes for isolated dystonia, especially with craniocervical involvement. To further determine the frequency and spectrum of ANO3/ GNAL mutations in familial dystonia, we recruited 33 pedigrees of Chinese origin with isolated dystonia (affected number n5 118, 53 focal [blepharospasm 11, torticollis 42], 7 segmental, 1 generalized, 57 dystonic tremor) and performed mutational screening of ANO3 (NM_031418) and GNAL (NM_001142339) in the 33 probands by direct Sanger sequencing (see Supplemental Data for pedigrees and characteristics). Informed consent was obtained from all participating individuals. All probands were negative for genetic testing of DYT1 (TOR1A), DYT6 (THAP1), and DYT23 (CIZ1). A heterozygous missense substitution, c.2540A>G (p.Y847C), was identified in the probands of families N and R. This substitution, resulting in a change from tyrosine to cysteine at position 847 of the protein (Fig. 1A), was not found in 100 healthy controls or reported in the publicly available databases of the public single-nucleotide polymorphism (www.ncbi.nlm. nih.gov/projects/SNP/), Exome Aggregation Consortium (Exac, http://exac.broadinstitute.org/), or National Heart, Lung, and Blood Institute exome sequencing project (NHLBI-ESP, http:// evs.gs.washington.edu/EVS/). It affected the amino acid that was highly conserved between species (Fig. 1B) and was predicted to be deleterious by MutationTaster, SIFT, and PolyPhen-2. This mutation also was found in two affected brothers (III-3 and III5) in family N, whereas unaffected individuals (III-7, III-8) were homozygous for the normal allele. We were unable to obtain DNA samples from the proband’s daughter of family R, because she did not wish to take part. The phenotypes of patients with Y847C mutation are shown in Figure 1C. Six other variants in the ANO3 gene, c.211G>T (rs143269109), c.2478C>G (p.T8265), c.2520T>G (p.R8405), c.1158A>G (p.L3865, rs2663168), c.1692A>C (p.A5645, rs11604868), and c.2682C>T (p.P8945, rs10835051), were also detected in the probands, leading to no amino acid change. The latter three variants were found in the control group as well. No variants were found in the GNAL gene. To date, two studies reported the frequency of ANO3 in isolated dystonia, varying from 0.59% (2/342) to 2.1% (4/188). Eleven missense mutations in ANO3, c.2540A>G (p.Y847C, our study), c.1480A>T (p.R494W), c.1470G>C (p.W490C), c.161C> T (p.T54I), c.2053A>G (p. S685G), c.2586G>T (p.K862N), c.2190C>T, c.2497A>G (p.I833V), c.2917G> C (p.G973R), c.704A >G (p.Y235C), c.767A >G (p.N256S), and c.2678C >T (p.P893L), have been identified, with the latter three found in healthy controls. No nonsense mutation or frameshift mutation was reported. Functional assay of c.2540A>G is needed to confirm its role in the pathogenesis of dystonia in the following work because computational tools such as MutationTaster, SIFT, and PolyPhen-2 do not yield 100% accuracy. In summary, we identified one missense mutation in the ANO3 gene, c.2540A>G (p.Y847C), in 2 of 33 isolated dystonia pedigrees. More studies will be needed to confirm the role of ANO3 gene in familial isolated dystonia.

Combined occurrence of a novel TOR1A and a THAP1 mutation in primary dystonia

The ΔGAG deletion of the TOR1A gene (DYT1) is responsible for DYT1 dystonia. However, no other TOR1A mutation has been reported in the Chinese population.

Brain-derived neurotrophic factor Val66Met polymorphism is not associated with primary dystonia in a Chinese population

BACKGROUND Brain-derived neurotrophic factor (BDNF) is a modulator of synaptic and neural plasticity. Considering the association between dystonia and abnormal sensorimotor cortex plasticity, BDNF may be a candidate gene that confers susceptibility to dystonia. However, the association between Val66Met polymorphism of BDNF gene and primary dystonia is controversial. METHODS A case-control study was performed to evaluate the association between Val66Met polymorphism in the BDNF gene and primary dystonia in a cohort of 252 Chinese patients and in 214 age- and gender-matched healthy control subjects. RESULTS No association was identified between Val66Met polymorphism and primary dystonia or cervical dystonia (P=0.309 and P=0.803 respectively). In a subsequent subgroup analysis, there was also no difference in the distribution for age of onset. CONCLUSION Our findings do not support that BDNF Val66Met polymorphism contributes to the risk of primary dystonia.

Novel gene mutations and clinical features in patients with pantothenate kinase-associated neurodegeneration.

Fig. 1. (a) Patients with compound heterozygous PANK2 gene mutations and their family members. The blackened squares denote the number of patients. (b) ‘Eye of the tiger sign’ of patients PKAN-02, 03 and 04 in T2-magnetic resonance imaging (MRI) image. We identified six Chinese patients with sporadic PKAN, all of whom revealed the typical ‘eye of the tiger’ sign upon brain magnetic resonance imaging (MRI). PANK2 mutational analyses were conducted in all patients and their available family members. Informed consents were obtained and blood samples were collected. The genotypes and clinical

Subthalamic Nuclei Stimulation in Patients With Pantothenate Kinase-Associated Neurodegeneration (PKAN)

Pantothenate kinase‐associated neurodegeneration (PKAN) is a rare autosomal recessive genetic disease that leads to extrapyramidal symptoms, such as dystonia, ataxia, dysarthria, and involuntary movements. Treatment of PKAN with deep brain stimulation (DBS) has been reported, but mainly focuses on targeting the globus pallidus internus (GPi). Subthalamic nuclei (STN) may also be a potential target for treatment of PKAN.

Prevalence of pre-diagnostic symptoms did not differ between LRRK2-related, GBA-related and idiopathic patients with Parkinson's disease

INTRODUCTION Glucocerebrosidase (GBA) mutations and leucine-rich repeat kinase 2 (LRRK2) variants are the most common genetic risk factors for late-onset Parkinsons disease (PD). In this study, we aimed to investigate the differences in pre-diagnostic symptoms of PD associated with the variants. METHODS The participants were recruited from 24 centers across China and genotyped for LRRK2 G2385R and R1628P variants and GBA L444P mutation. Participants were surveyed with structural questionnaires for history of environmental exposure and living habits and interviewed to collect the time at onset of each symptoms before diagnosis. We compared the cumulative prevalence and manifestation pattern of symptoms between groups using multiple logistic regression, adjusting age and gender. RESULTS Total 1799 PD patients were recruited, including 226 patients with LRRK2 G2385R or R1628P variant, 44 with GBA L444P mutation, three with both LRRK2 and GBA mutation, and 1526 idiopathic patients. The cumulative prevalence of non-motor and typical motor symptoms did not differ between groups before diagnosis (P > 0.05). The manifestation sequences of non-motor symptoms were indistinguishable between the LRRK2-carriers, GBA-carriers, and idiopathic PD subjects, and followed the sequence of constipation, hyposmia, sleep disorders, anxiety and depression, sexual dysfunction, urinary incontinency, dizziness and cognition. Slightly higher prevalence of hypomimia and micrographia were detected in the GBA-carriers. CONCLUSIONS The prevalence of pre-diagnostic symptoms is almost indistinguishable between the LRRK2-carriers, GBA-carriers, and idiopathic PD before diagnosis; the sequence of the manifestation of non-motor symptoms largely conforms to the Braak stage for both genetic-related and idiopathic late-onset PD.

Novel SERAC1 mutations in a Chinese patient presenting with parkinsonism and dystonia

A 22-year-old man was admitted to our hospital complaining of bradykinesia of the limbs, abnormal posture of neck and feet, and slurred speech. The patient was the only child born to healthy nonconsanguineous Chinese parents. Family history was unremarkable. Delivery history of the patient was normal following an unremarkable pregnancy. His parents noted the patient experienced neonatal jaundice several days after birth and symptoms resolved with phototherapy treatment. Childhood development was normal until 12 years of age followed by progressive slurred speech, clumsiness, and bradykinesia of limbs. Strephenopodia was observed when walking. At 19 years old, the patient developed spasmodic torticollis with sensory tricks. Hearing loss, visual defect, and epilepsy were not complained. Cognitive evaluation using MMSE (Mini-Mental State Examination) had a score of 27/30. Physical examination was conducted by two specialists in movement disorders (Dr. XH Wan and Dr. L Wang) and revealed dysarthria and abnormal head posture with left side rotation. The muscle tone of all limbs were increased. A festinating gait was also noticed. Limb strength and bilateral deep tendon reflexes were normal with negative pathological reflex. Laboratory tests including complete blood count, erythrocyte sedimentation rate, copper, ceruloplasmin, thyroid hormone levels, folic acid, and vitamin B12 were within the normal range. Serum ammonia, cholesterol, and lactic acid were also within normal range. Liver function analysis showed increased total bilirubin of 29.4 μmol/L (normal range 5.1– 22.2 μmol/L) and direct bilirubin of 10.9 μmol/L (normal range 0–6.8 μmol/L) with normal aminotransferases and coagulation profile. Ophthalmological examinations and hearing screening were unremarkable. Magnetic resonance imaging (MRI) of the brain showed no obvious abnormalities. Urine organic acid analysis showed elevated excretion of 3methylglutaconic and 3-methylglutaric acids. Because of the patient’s remarkable dystonia and parkinsonism, targeted gene capture-based next-generation sequencing, including 148 genes associated with dystonia and parkinsonism, was then performed and two novel heterozygous variants were identified in SERAC1 gene (c.1498G>A, p.Gly500Arg and c.1645_1646insATC, p.548_549insHis). Segregation analysis revealed that the variants were inherited from his father and mother respectively (Fig. 1). Symptomatic medical interventions, including benserazide-levodopa, baclofen, and benzhexol, were of little effect. Botulinum toxin A injection was administered and abnormal neck posture was partially improved.