Clinical profiles and outcomes of deep brain stimulation in G2019S LRRK2 Parkinson disease.

OBJECTIVE: The objective of this study was to evaluate clinical features and response to deep brain stimulation (DBS) in G2019S LRRK2-Parkinson disease (LRRK2-PD) and idiopathic PD (IPD). METHODS: The authors conducted a clinic-based cohort study of PD patients recruited from the Mount Sinai Beth Israel Genetics database of PD studies. The cohort included 87 participants with LRRK2-PD (13 who underwent DBS) and 14 DBS participants with IPD enrolled between 2009 and 2017. The baseline clinical features, including motor ratings and levodopa-equivalent daily dose (LEDD), were compared among LRRK2-PD patients with and without DBS, between LRRK2-PD with DBS and IPD with DBS, and between LRRK2-PD with subthalamic nucleus (STN) and internal segment of the globus pallidus (GPi) DBS. Longitudinal motor scores (Unified Parkinson's Disease Rating Scale-part III) and medication usage were also assessed pre- and postoperatively. RESULTS: Compared to LRRK2-PD without DBS (n = 74), the LRRK2-PD with DBS cohort (n = 13) had a significantly younger age of onset, longer disease duration, were more likely to have dyskinesia, and were less likely to experience hand tremor at disease onset. LRRK2-PD participants were also more likely to be referred for surgery because of severe dyskinesia (11/13 [85%] vs 6/14 [43%], p = 0.04) and were less likely to be referred for medically refractory tremor (0/13 [0%] vs 6/14 [43%], p = 0.02) than were IPD patients. Among LRRK2-PD patients, both STN-DBS and GPi-DBS targets were effective, although the sample size was small for both groups. There were no revisions or adverse effects reported in the GPi-DBS group, while 2 of the LRRK2-PD participants who underwent STN-DBS required revisions and a third reported depression as a stimulation-related side effect. Medication reduction favored the STN group. CONCLUSIONS: The LRRK2-PD cohort referred for DBS had a slightly different profile, including earlier age of onset and dyskinesia. Both the STN and GPi DBS targets were effective in symptom suppression. Patients with G2019S LRRK2 PD were well-suited for DBS therapy and had favorable motor outcomes regardless of the DBS target. LRRK2-DBS patients had longer disease durations and tended to have more dyskinesia. Dyskinesia commonly served as the trigger for DBS surgical candidacy. Medication-refractory tremor was not a common indication for surgery in the LRRK2 cohort.

Cancer outcomes among Parkinson's disease patients with leucine rich repeat kinase 2 mutations, idiopathic Parkinson's disease patients, and nonaffected controls.

BACKGROUND: Increased cancer risk has been reported in Parkinson's disease (PD) patients carrying the leucine rich repeat kinase 2 (LRRK2) G2019S mutation (LRRK2-PD) in comparison with idiopathic PD (IPD). It is unclear whether the elevated risk would be maintained when compared with unaffected controls. METHODS: Cancer outcomes were compared among 257 LRRK2-PD patients, 712 IPD patients, and 218 controls recruited from 7 LRRK2 consortium centers using mixed-effects logistic regression. Data were then pooled with a previous study to examine cancer risk between 401 LRRK2-PD and 1946 IPD patients. RESULTS: Although cancer prevalence was similar among LRRK2-PD patients (32.3%), IPD patients (27.5%), and controls (27.5%; P = 0.33), LRRK2-PD had increased risks of leukemia (odds ratio [OR] = 4.55; 95% confidence interval [CI], 1.46-10.61) and skin cancer (OR = 1.61; 95% CI, 1.09-2.37). In the pooled analysis, LRRK2-PD patients had also elevated risks of leukemia (OR = 9.84; 95% CI, 2.15-44.94) and colon cancer (OR = 2.34; 95% CI, 1.15-4.74) when compared with IPD patients. CONCLUSIONS: The increased risks of leukemia as well as skin and colon cancers among LRRK2-PD patients suggest that LRRK2 mutations heighten risks of certain cancers. © 2019 International Parkinson and Movement Disorder Society.

Complex and Dynamic Chromosomal Rearrangements in a Family With Seemingly Non-Mendelian Inheritance of Dopa-Responsive Dystonia.

Importance: Chromosomal rearrangements are increasingly recognized to underlie neurologic disorders and are often accompanied by additional clinical signs beyond the gene-specific phenotypic spectrum. Objective: To elucidate the causal genetic variant in a large US family with co-occurrence of dopa-responsive dystonia as well as skeletal and eye abnormalities (ie, ptosis, myopia, and retina detachment). Design, Setting, and Participants: We examined 10 members of a family, including 5 patients with dopa-responsive dystonia and skeletal and/or eye abnormalities, from a US tertiary referral center for neurological diseases using multiple conventional molecular methods, including fluorescence in situ hybridization and array comparative genomic hybridization as well as large-insert whole-genome sequencing to survey multiple classes of genomic variations. Of note, there was a seemingly implausible transmission pattern in this family due to a mutation-negative obligate mutation carrier. Main Outcomes and Measures: Genetic diagnosis in affected family members and insight into the formation of large deletions. Results: Four members were diagnosed with definite and 1 with probable dopa-responsive dystonia. All 5 affected individuals carried a large heterozygous deletion encompassing all 6 exons of GCH1. Additionally, all mutation carriers had congenital ptosis requiring surgery, 4 had myopia, 2 had retinal detachment, and 2 showed skeletal abnormalities of the hands, ie, polydactyly or syndactyly or missing a hand digit. Two individuals were reported to be free of any disease. Analyses revealed complex chromosomal rearrangements on chromosome 14q21-22 in unaffected individuals that triggered the expansion to a larger deletion segregating with affection status. The expansion occurred recurrently, explaining the seemingly non-mendelian inheritance pattern. These rearrangements included a deletion of GCH1, which likely contributes to the dopa-responsive dystonia, as well as a deletion of BMP4 as a potential cause of digital and eye abnormalities. Conclusions and Relevance: Our findings alert neurologists to the importance of clinical red flags, ie, unexpected co-occurrence of clinical features that may point to the presence of chromosomal rearrangements as the primary disease cause. The clinical management and diagnostics of such patients requires an interdisciplinary approach in modern clinical-diagnostic care.

Olfactory identification in LRRK2 G2019S mutation carriers: a relevant marker?

OBJECTIVE: Olfactory impairment is a potential marker for impending phenoconversion to Parkinson disease (PD) that may precede the development of disease by several years. Because of low specificity, it may be of greater predictive value in those with genetic mutations and its potential as a marker for developing LRRK2 PD should be evaluated. METHODS: We examined olfactory identification in 126 LRRK2 G2019S mutation carriers with PD, 125 mutation carriers not manifesting PD, 126 noncarriers with idiopathic PD, 106 noncarrier family members without PD, and 35 unrelated controls. We compared olfactory performance and performed mixture modeling to identify possible subgroups of olfactory performance in LRRK2 PD and nonmanifesting carriers. RESULTS: Adjusting for sex, age, cognitive score, site, and smoking history, LRRK2 PD had better olfactory scores compared to idiopathic PD (mean olfaction difference: -3.7, P < 0.001), and both LRRK2 PD and idiopathic PD had worse olfaction than controls (-12.8, -9.1, both P < 0.001). LRRK2 PD were less likely to be hyposmic than idiopathic PD (54.8% vs. 80.2%, P < 0.001). Nonmanifesting carriers and noncarrier family members did not differ. Mixture model analysis identified three classes in the LRRK2 PD and nonmanifesting carriers, suggesting that there are subgroups with poor olfactory identification in both LRRK2 PD and nonmanifesting carriers. INTERPRETATION: Therefore, olfactory identification deficit is less likely to be an obligate feature in LRRK2 PD than idiopathic PD, and while a relevant marker in some, a subset of carriers who eventually phenoconvert may proceed directly to PD without prior impaired olfaction.

Heterogeneity in primary dystonia: lessons from THAP1, GNAL, and TOR1A in Amish-Mennonites.

A founder mutation in the Thanatos-associated (THAP) domain containing, apoptosis associated protein 1 (THAP1) gene causing primary dystonia was originally described in the Amish-Mennonites. However, there may be both genotypic and phenotypic heterogeneity of dystonia in this population that may also inform studies in other ethnic groups. Genotyping for THAP1 and for guanine nucleotide binding protein (G protein), α-activating activity polypeptide, olfactory type (GNAL) mutations and genotype-phenotype comparisons were performed for 76 individuals of Amish-Mennonites heritage with primary dystonia. Twenty-seven individuals had mutations in THAP1-most with the founder indel mutation-but two had different THAP1 mutations, 8 had mutations in GNAL, and 1 had a de novo GAG deletion in torsin 1A (TOR1A) (dystonia 1 [DYT1]). In the primary analysis comparing THAP1 carriers versus all non-THAP1, non-GNAL, non-TOR1A individuals, age at onset was lower in THAP1 carriers (mean age ± standard deviation, 15.5 ± 9.2 years [range, 5-38 years] vs. 39.2 ± 17.7 years [range, 1-70 years]; P < 0.001), and THAP1 carriers were more likely to have onset of dystonia in an arm (44.4% vs. 15.0%; P = 0.02) and to have arm involvement (88.9% vs. 22.5%; P < 0.01), leg involvement (51.9% vs. 10.0%; P = 0.01), and jaw/tongue involvement (33.3% vs. 7.5%; P = 0.02) involvement at their final examination. Carriers were less likely to have dystonia restricted to a single site (11.11% in carriers vs. 65.9% in noncarriers; P < 0.01) and were less likely to have dystonia onset in cervical regions (25.9% of THAP1 carriers vs. 52.5% of noncarriers; P = 0.04). Primary dystonia in the Amish-Mennonites is genetically diverse and includes not only the THAP1 indel founder mutation but also different mutations in THAP1 and GNAL as well as the TOR1A GAG deletion. Phenotype, particularly age at onset combined with final distribution, may be highly specific for the genetic etiology.

LRRK2 G2019S mutations are associated with an increased cancer risk in Parkinson disease.

Leucine rich repeat kinase (LRRK2) G2019S mutations are presumed to cause PD through a toxic gain of function of the protein kinase. Small molecule kinase inhibitors have been developed for the treatment of certain cancers, and some antioncogenic agents such as sunitinib, may nonspecifically inhibit LRRK2. Few studies, however, have assessed cancer risk in LRRK2 mutation carriers. To explore this risk, we evaluated records of Ashkenazi Jewish (AJ) PD patients participating in genetic research. Charts were reviewed for 163 unrelated AJ PD patients, 31 of whom harbored the G2019S mutation. History of cancer was queried at baseline intake using a form reviewing medical conditions, and charts were reviewed for all follow-up visits. 9/31 LRRK2 G2019S mutation carriers had nonskin cancers, whereas 15/132 without mutations had nonskin cancers, representing an almost threefold increased risk in this group (HR 2.9, 95% CI 1.3-6.6). Age at first nonskin cancer was younger in the LRRK2 carriers (56.0 years) than the noncarriers (62.0 years), but was not significant. 67% of the LRRK2 carriers had their cancer before the onset of PD, whereas only 40% of noncarriers developed their first nonskin cancer before onset of PD. While further evaluation is warranted, our findings indicate an increased risk of nonskin cancers in LRRK2 G2019S mutation carriers, which may be related to toxic gain of function of mutated LRRK2.

Clinical and neurophysiological improvement of SGCE myoclonus-dystonia with GPi deep brain stimulation.

Myoclonus-dystonia (M-D) is characterized by early onset myoclonus and dystonia. It is thought to be subcortical in origin. Response to oral medications may be incomplete, such that deep brain stimulation (DBS) surgery to the globus pallidum interna (GPi) or ventral intermediate thalamic nucleus (VIM) may be considered. The optimal site is not known. The physiology and surgical response for a 63-year-old woman who underwent GPi DBS for M-D with onset at age 2 and related to a mutation in the epsilon-sarcoglycan gene (SGCE) is described. She showed excellent clinical and neurophysiological improvement of both myoclonus and dystonia, suggesting that modulation by DBS is effective even after long disease duration and only partial response to oral medications.

The phenotypic spectrum of rapid-onset dystonia-parkinsonism (RDP) and mutations in the ATP1A3 gene.

Rapid-onset dystonia-parkinsonism (RDP) (also known as DYT12) is characterized by the abrupt onset of dystonia and parkinsonism and is caused by mutations in the ATP1A3 gene. We obtained clinical data and sequenced the ATP1A3 gene in 49 subjects from 21 families referred with 'possible' RDP, and performed a genotype-phenotype analysis. Of the new families referred for study only 3 of 14 families (21%) demonstrated a mutation in the ATP1A3 gene, but no new mutations were identified beyond our earlier report of 6. Adding these to previously reported families, we found mutations in 36 individuals from 10 families including 4 de novo mutations and excluded mutations in 13 individuals from 11 families. The phenotype in mutation positive patients included abrupt onset of dystonia with features of parkinsonism, a rostrocaudal gradient, and prominent bulbar findings. Other features found in some mutation carriers included common reports of triggers, minimal or no tremor at onset, occasional mild limb dystonia before the primary onset, lack of response to dopaminergic medications, rare abrupt worsening of symptoms later in life, stabilization of symptoms within a month and minimal improvement overall. In comparing ATP1A3 mutation positive and negative patients, we found that tremor at onset of symptoms, a reversed rostrocaudal gradient, and significant limb pain exclude a diagnosis of RDP. A positive family history is not required. Genetic testing for the ATP1A3 gene is recommended when abrupt onset, rostrocaudal gradient and prominent bulbar findings are present.