Multisystem ALK-Positive Histiocytosis With DCTN1::ALK Fusion in an Adult, Responsive to Alectinib: Case Report and Literature Review.

Anaplastic lymphoma kinase (ALK)-positive histiocytosis has emerged as a clinically relevant diagnosis featuring a wide span of clinical presentations, which are unified by the presence of ALK-positive histiocytes on histopathology and molecular drivers involving the ALK kinase gene. This report presents an adult case of multisystem ALK-positive histiocytosis with xanthogranuloma-like features on histopathology that was responsive to ALK inhibition, and includes a review of ALK-positive histiocytoses with cutaneous involvement reported in the literature. A 56-year-old male developed a widespread eruption of red-brown papules on the face, trunk, and upper extremities. Histopathological evaluation revealed a well-circumscribed, nodular dermal infiltrate of epithelioid histiocytes with Touton giant cells, rare bizarre multinucleated cells, and focal emperipolesis. The lesional cells were positive for CD68 and ALK1 immunohistochemical stains, and negative for CD1a. Next-generation sequencing identified a DCTN1::ALK fusion. On imaging, he was found to have bone, lung, soft tissue, and salivary gland involvement. ALK inhibition was initiated with alectinib, resulting in rapid improvement of cutaneous lesions and eventual complete resolution of abnormal imaging findings, which was sustained at 24 months of follow-up. This case adds to the spectrum of ALK-positive histiocytoses and further demonstrates the positive response with targeted therapy.

Wild-Type DCTN1 Suppresses the Aggregation of DCTN1 Mutants Associated with Perry Disease.

Perry disease, a rare autosomal dominant neurodegenerative disorder, is characterized by parkinsonism, depression or apathy, unexpected weight loss, and central hypoventilation. Genetic analyses have revealed a strong association between point mutations in the dynactin I gene (DCTN1) coding p150glued and Perry disease. Although previous reports have suggested a critical role of p150glued aggregation in Perry disease pathology, whether and how p150glued mutations affect protein aggregation is not fully understood. In this study, we comprehensively investigated the intracellular distribution of the p150glued mutants in HEK293T cells. We further assessed the effect of co-overexpression of the wild-type p150glued protein with mutants on the formation of mutant aggregates. Notably, overexpression of p150glued mutants identified in healthy controls, which is also associated with amyotrophic lateral sclerosis, showed a thread-like cytoplasmic distribution, similar to the wild-type p150glued. In contrast, p150glued mutants in Perry disease and motor neuron disease caused aggregation. In addition, the co-overexpression of the wild-type protein with p150glued mutants in Perry disease suppressed aggregate formation. In contrast, the p150glued aggregation of motor neuron disease mutants was less affected by the wild-type p150glued. Further investigation of the mechanism of aggregate formation, contents of the aggregates, and biological mechanisms of Perry disease could help develop novel therapeutics.

Clinical and neurophysiological characterization of p.Gly59Ser mutation in DCTN1: a study in a Thai family and a brief review.

INTRODUCTION: Mutations in the Dynactin 1 (DCTN1) gene lead to various neurodegenerative disorders. The p.Gly59Ser mutation, the first pathogenic mutation identified in DCTN1, was initially reported in a family with distal hereditary motor neuropathy and early vocal cord paralysis. Since its discovery in 2003, this mutation has been documented in only three families worldwide, to the best of our knowledge. METHODS: This study examines six patients from a Thai family carrying the p.Gly59Ser mutation in DCTN1 and includes a literature review. RESULTS: Five of the patients were female. The mean age of onset was 32.6 ± 1.9 years. Thai patients showed early involvement of intrinsic hand, facial, and bulbar muscles, with vocal cord impairment manifesting later in the disease course. Tongue fasciculations, not previously reported with this mutation, were observed in most Thai patients. Bilateral split-hands were consistently noted. Arytenoidectomy and cordotomy have proven beneficial in relieving upper airway obstruction and preventing life-threatening upper airway complications from vocal cord paralysis. CONCLUSIONS: The p.Gly59Ser mutation in DCTN1 presents with autosomal-dominant, adult-onset, lower motor neuronopathy/neuropathy. Compared to earlier reports, Thai patients exhibited more widespread involvement, including facial, bulbar, tongue, vocal cord, and limb muscles. In addition to vocal cord paralysis, the split-hand phenomenon emerges as another clinical hallmark of this condition.

Dynactin 1 negatively regulates HIV-1 infection by sequestering the host cofactor CLIP170.

Many viruses directly engage and require the dynein-dynactin motor-adaptor complex in order to transport along microtubules (MTs) to the nucleus and initiate infection. HIV type 1 (HIV-1) exploits dynein, the dynein adaptor BICD2, and core dynactin subunits but unlike several other viruses, does not require dynactin-1 (DCTN1). The underlying reason for HIV-1's variant dynein engagement strategy and independence from DCTN1 remains unknown. Here, we reveal that DCTN1 actually inhibits early HIV-1 infection by interfering with the ability of viral cores to interact with critical host cofactors. Specifically, DCTN1 competes for binding to HIV-1 particles with cytoplasmic linker protein 170 (CLIP170), one of several MT plus-end tracking proteins (+TIPs) that regulate the stability of viral cores after entry into the cell. Outside of its function as a dynactin subunit, DCTN1 also functions as a +TIP that we find sequesters CLIP170 from incoming particles. Deletion of the Zinc knuckle (Zn) domain in CLIP170 that mediates its interactions with several proteins, including DCTN1, increased CLIP170 binding to virus particles but failed to promote infection, further suggesting that DCTN1 blocks a critical proviral function of CLIP170 mediated by its Zn domain. Our findings suggest that the unique manner in which HIV-1 binds and exploits +TIPs to regulate particle stability leaves them vulnerable to the negative effects of DCTN1 on +TIP availability and function, which may in turn have driven HIV-1 to evolve away from DCTN1 in favor of BICD2-based engagement of dynein during early infection.

Clinical, pathological and genetic characteristics of Perry disease-new cases and literature review.

BACKGROUND AND PURPOSE: Perry disease (or Perry syndrome) is an autosomal dominant neurodegenerative disorder characterized by parkinsonism, neuropsychiatric symptoms, central hypoventilation, weight loss and distinct TDP-43 pathology. It is caused by mutations of the DCTN1 gene encoding an essential component of axonal transport. The objectives were to provide the current state of knowledge on clinical, pathological and genetic aspects of Perry disease, as well as practical suggestions for the management of the disease. METHODS: Data on new patients from New Zealand, Poland and Colombia were collected, including autopsy report. Also all of the published papers since the original work by Perry in 1975 were gathered and analyzed. RESULTS: Parkinsonism was symmetrical, progressed rapidly and was poorly responsive to L-Dopa; nonetheless, a trial with high doses of L-Dopa is warranted. Depression was severe, associated with suicidal ideations, and benefited from antidepressants and L-Dopa. Respiratory symptoms were the leading cause of death, and artificial ventilation or a diaphragm pacemaker prolonged survival. Weight loss occurred in most patients and was of multifactorial etiology. Autonomic dysfunction was frequent but underdiagnosed. There was a clinical overlap with other neurodegenerative disorders. An autopsy showed distinctive pallidonigral degeneration with TDP-43 pathology. Genetic testing provided evidence of a common founder for two families. There was striking phenotypic variability in DCTN1-related disorders. It is hypothesized that oligogenic or polygenic inheritance is at play. CONCLUSIONS: Perry disease and other DCTN1-related diseases are increasingly diagnosed worldwide. Relatively effective symptomatic treatments are available. Further studies are needed to pave the way toward curative/gene therapy.

A novel Q93H missense mutation in DCTN1 caused distal hereditary motor neuropathy type 7B and Perry syndrome from a Chinese family.

The Dynactin 1 (DCTN1) encodes the p150 subunit of dynactin, which engages retrograde axonal transport. Missense mutations in DCTN1 have been linked to a series of neurodegenerative diseases, including distal hereditary motor neuropathies (dHMN) and Perry syndrome. A few pathogenic DCTN1 mutations related with Perry syndrome have been described within, or adjacent to, the highly conserved N-terminal cytoskeleton-associated protein, glycine-rich (CAP-Gly) domain. But to our best knowledge, only the pathogenic G59S mutation in DCTN1 has been reported in dHMN7B families. Herein, we provided a novel heterozygous mutation in DCTN1 which caused both dHMN7B and Perry syndrome from a Chinese family. Whole exome sequencing (WES) was performed to identify the disease-associated genes. Single nucleotide variants (SNVs) and small insertions/deletions (INDELs) were further predicted with Mutation Taster, Polymorphism Phenotyping v2 (PolyPhen-2), and Sorting Intolerant From Tolerant (SIFT) and compared to the Single Nucleotide Polymorphism Database(dbSNP), Exome Aggregation Consortium (ExAC), and the 1000 Genomes Project. Furthermore, a novel missense mutation c.279G>C (Q93H) in DCTN1 was identified as the candidate loci. The mutation was confirmed with Sanger sequencing in the family members and cosegregated with various phenotypes. In silico analysis and molecular structural modeling, the mutation not only caused the loss of a hydrogen bond within the p150 protein but also affected the formation of hydrogen bonds between p150 and EB. Therefore, the new Q93H mutation in DCTN1 caused both familial dHMN7B and Perry syndrome. Our findings could expand the clinical and pathogenic spectrum and strengthen the clinical diagnostic role of the DCTN1 gene.

DCTN1 Binds to TDP-43 and Regulates TDP-43 Aggregation.

A common pathological hallmark of several neurodegenerative diseases, including amyotrophic lateral sclerosis, is cytoplasmic mislocalization and aggregation of nuclear RNA-binding protein TDP-43. Perry disease, which displays inherited atypical parkinsonism, is a type of TDP-43 proteinopathy. The causative gene DCTN1 encodes the largest subunit of the dynactin complex. Dynactin associates with the microtubule-based motor cytoplasmic dynein and is required for dynein-mediated long-distance retrograde transport. Perry disease-linked missense mutations (e.g., p.G71A) reside within the CAP-Gly domain and impair the microtubule-binding abilities of DCTN1. However, molecular mechanisms by which such DCTN1 mutations cause TDP-43 proteinopathy remain unclear. We found that DCTN1 bound to TDP-43. Biochemical analysis using a panel of truncated mutants revealed that the DCTN1 CAP-Gly-basic supradomain, dynactin domain, and C-terminal region interacted with TDP-43, preferentially through its C-terminal region. Remarkably, the p.G71A mutation affected the TDP-43-interacting ability of DCTN1. Overexpression of DCTN1G71A, the dynactin-domain fragment, or C-terminal fragment, but not the CAP-Gly-basic fragment, induced cytoplasmic mislocalization and aggregation of TDP-43, suggesting functional modularity among TDP-43-interacting domains of DCTN1. We thus identified DCTN1 as a new player in TDP-43 cytoplasmic-nuclear transport, and showed that dysregulation of DCTN1-TDP-43 interactions triggers mislocalization and aggregation of TDP-43, thus providing insights into the pathological mechanisms of Perry disease and other TDP-43 proteinopathies.

HPS6 interacts with dynactin p150Glued to mediate retrograde trafficking and maturation of lysosomes.

Hermansky-Pudlak syndrome 6 protein (HPS6) has originally been identified as a subunit of the BLOC-2 protein complex that is involved in the biogenesis of lysosome-related organelles. Here, we demonstrate that HPS6 directly interacts with the dynactin p150(Glued) subunit of the dynein-dynactin motor complex and acts as cargo adaptor for the retrograde motor to mediate the transport of lysosomes from the cell periphery to the perinuclear region. Small interfering RNA (siRNA)-mediated knockdown of HPS6 in HeLa cells not only partially blocks centripetal movement of lysosomes but also causes delay in lysosome-mediated protein degradation. Moreover, lysosomal acidification and degradative capacity, as well as fusion between late endosomes and/or multivesicular bodies and lysosomes are also impaired when HPS6 is depleted, suggesting that perinuclear positioning mediated by the dynein-dynactin motor complex is required for lysosome maturation and activity. Our results have uncovered a so-far-unknown specific role for HPS6 in the spatial distribution of the lysosomal compartment.

First family with Perry syndrome from Mexico.

Perry syndrome (PS) is a rare autosomal dominant disease characterized by parkinsonism, central hypoventilation, weight loss and depression and is caused by pathogenic mutations in the dynactin subunit 1 (DCTN1) gene (encoding p150glued protein). To date, only two cases have been reported in Latin America, specifically in Colombia and Argentina. The present study, to the best of our knowledge, reports the first recorded Mexican family with PS. The clinical features of the proband and a family history of early parkinsonism led to the suspicion of PS. The pathogenic variant NM_004082:c.212G>A, causing a (p.Gly71Glu) mutation in the p150glued protein, was identified in exon 2 of the DCTN1 gene by exome sequencing, confirming the diagnosis of PS. (p.Gly71Glu) has been previously identified in at least 4 cases of PS from different ethnic backgrounds. Genetic counseling was provided to the available family members. To clarify the impact of the (p.Gly71Glu) variant on the structure and function of the cytoskeleton-associated protein Gly rich (CAP-Gly) domain of p150glued, Glu71 mutated CAP-Gly domains were modeled and compared with the wild-type. It was hypothesized that the larger and more charged side chain of Glu may induce conformational and electrostatic changes, imposing a conformational restriction on the peptide backbone that would affect interaction with the p150glued protein partners, causing dysfunction in the dynactin protein complex.

Dysregulation of stress granule dynamics by DCTN1 deficiency exacerbates TDP-43 pathology in Drosophila models of ALS/FTD.

The abnormal aggregation of TDP-43 into cytoplasmic inclusions in affected neurons is a major pathological hallmark of amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD). Although TDP-43 is aberrantly accumulated in the neurons of most patients with sporadic ALS/FTD and other TDP-43 proteinopathies, how TDP-43 forms cytoplasmic aggregates remains unknown. In this study, we show that a deficiency in DCTN1, a subunit of the microtubule-associated motor protein complex dynactin, perturbs the dynamics of stress granules and drives the formation of TDP-43 cytoplasmic aggregation in cultured cells, leading to the exacerbation of TDP-43 pathology and neurodegeneration in vivo. We demonstrated using a Drosophila model of ALS/FTD that genetic knockdown of DCTN1 accelerates the formation of ubiquitin-positive cytoplasmic inclusions of TDP-43. Knockdown of components of other microtubule-associated motor protein complexes, including dynein and kinesin, also increased the formation of TDP-43 inclusions, indicating that intracellular transport along microtubules plays a key role in TDP-43 pathology. Notably, DCTN1 knockdown delayed the disassembly of stress granules in stressed cells, leading to an increase in the formation of pathological cytoplasmic inclusions of TDP-43. Our results indicate that a deficiency in DCTN1, as well as disruption of intracellular transport along microtubules, is a modifier that drives the formation of TDP-43 pathology through the dysregulation of stress granule dynamics.

Whole-exome sequencing in a cohort of Chinese patients with isolated cervical dystonia.

Background: Dystonia is a kind of movement disorder but its pathophysiological mechanisms are still largely unknown. Recent evidence reveals that genetical defects may play important roles in the pathogenesis of dystonia. Objectives and Methods: -To explore possible causative genes in Chinese dystonia patients, DNA samples from 42 sporadic patients with isolated cervical dystonia were subjected to whole-exome sequencing. Rare deleterious variants associated with dystonia phenotype were screened out and then classified according to the American College of Medical Genetics and Genomics (ACMG) criteria. Phenolyzer was used for analyzing the most probable candidates correlated with dystonia phenotype, and SWISS-MODEL server was for predicting the 3D structures of variant proteins. Results: Among 42 patients (17 male and 25 female) recruited, a total of 36 potentially deleterious variants of dystonia-associated genes were found in 30 patients (30/42, 71.4 %). Four disease-causing variants including a pathogenic variant in PLA2G6 (c.797G > C) and three likely pathogenic variants in DCTN1 (c.73C > T), SPR (c.1A > C) and TH (c.56C > G) were found in four patients separately. Other 32 variants were classified as uncertain significance in 26 patients. Phenolyzer prioritized genes TH, PLA2G6 and DCTN1 as the most probable candidates correlated with dystonia phenotype. Although 3D prediction of DCTN1 and PLA2G6 variant proteins detected no obvious structural alterations, the mutation in DCTN1 (c.73C > T:p.Arg25Trp) was closely adjacent to its key functional domain. Conclusion: Our whole-exome sequencing results identified a novel variant in DCTN1 in sporadic Chinese patients with isolated cervical dystonia, which however, needs our further study on its exact role in dystonia pathogenesis.

Perry Disease: Expanding the Genetic Basis.

Background: Perry disease (or Perry syndrome [PS]) is a hereditary neurodegenerative disorder inevitably leading to death within few years from onset. All previous cases with pathological confirmation were caused by mutations within the cytoskeleton-associated protein glycine-rich (CAP-Gly) domain of the DCTN1 gene. Objectives: This paper presents the first clinicopathological report of PS due to a novel DCTN1 mutation outside the CAP-Gly domain. Methods: Clinical and pathological features of the new variant carrier are compared with another recently deceased PS case with a well-known pathogenic DCTN1 mutation and other reported cases. Results and Conclusions: We report a novel DCTN1 mutation outside the CAP-Gly domain that we demonstrated to be pathogenic based on clinical and autopsy findings.

Reduced levels of ALS gene DCTN1 induce motor defects in Drosophila.

Amyotrophic lateral sclerosis (ALS) is a rapidly progressive neuromuscular disease that has a strong genetic component. Deleterious variants in the DCTN1 gene are known to be a cause of ALS in diverse populations. DCTN1 encodes the p150 subunit of the molecular motor dynactin which is a key player in the bidirectional transport of cargos within cells. Whether DCTN1 mutations lead to the disease through either a gain or loss of function mechanism remains unresolved. Moreover, the contribution of non-neuronal cell types, especially muscle tissue, to ALS phenotypes in DCTN1 carriers is unknown. Here we show that gene silencing of Dctn1, the Drosophila main orthologue of DCTN1, either in neurons or muscles is sufficient to cause climbing and flight defects in adult flies. We also identify Dred, a protein with high homology to Drosophila Dctn1 and human DCTN1, that on loss of function also leads to motoric impairments. A global reduction of Dctn1 induced a significant reduction in the mobility of larvae and neuromuscular junction (NMJ) deficits prior to death at the pupal stage. RNA-seq and transcriptome profiling revealed splicing alterations in genes required for synapse organisation and function, which may explain the observed motor dysfunction and synaptic defects downstream of Dctn1 ablation. Our findings support the possibility that loss of DCTN1 function can lead to ALS and underscore an important requirement for DCTN1 in muscle in addition to neurons.

Diagnosis across a cohort of "atypical" atypical and complex parkinsonism.

INTRODUCTION: The diagnostic approach for adulthood parkinsonism can be challenging when atypical features hamper its classification in one of the two main parkinsonian groups: Parkinson's disease or atypical parkinsonian syndromes (APS). Atypical features are usually associated with non-sporadic neurodegenerative causes. METHODS: Retrospective analysis of patients with a working clinical diagnosis of "atypical" APS and complex parkinsonism. "Atypical" APS were classified according to the diagnostic research criteria and the "4-step diagnostic approach" (Stamelou et al. 2013). When not indicated, the final aetiological diagnosis was prospectively assessed. Brain MRI of progressive supranuclear palsy (PSP) look-alikes was reviewed by a neuroradiologist. RESULTS: Among 18 patients enrolled, ten were assigned to the "atypical" APS and eight to the complex parkinsonism group. In the "atypical" APS group, nine patients had PSP and one had corticobasal degeneration. In the PSP group the median magnetic resonance parkinsonism index was 17.1. A final aetiological diagnosis was established for 11 patients, four from the complex parkinsonism (L-2-hidroxiglutaric aciduria and DiGeorge syndrome) and seven from the "atypical" APS (Perry syndrome, postencephalitic PSP, vascular PSP, and MTP-AT6 mitochondrial disease) group. CONCLUSIONS: In this study, the identification of atypical APS features, as proposed in the "4-step diagnostic approach", successfully guided the investigation of alternative diagnoses. Distinctive non-neurodegenerative etiologies causing "atypical" atypical and complex parkinsonism were uncovered, including acquired (post-encephalitis and vascular) and genetic (MTP-AT6 mitochondrial disease mimicking PSP, described for the first time) ones. In the future, accurate clinical identification and distinction between neurodegenerative and non-neurodegenerative parkinsonism etiologies will allow for refining clinical trials.

L-Dopa response, choreic dyskinesia, and dystonia in Perry syndrome.

INTRODUCTION: A marked response to L-Dopa and L-Dopa-induced dyskinesia (LID) make the diagnosis of Parkinson's disease (PD) highly likely. This paper evaluates response to L-Dopa in Perry syndrome (PS), parkinsonism with distinct molecular and neuropathologic characteristics. METHODS: Six patients with PS with a mean follow-up of 5 years (0.5-12) were assessed by movement disorder specialists and video recorded in states off and on. Additionally, DATSCAN-SPECT was performed in 3 subjects. RESULTS: Four patients displayed a marked and sustained response to L-Dopa and LID. Additionally, we observed a distinct pattern of off-state predominant craniocervical dystonia responsive to L-Dopa in 4 patients, truncal dystonia in one, and dystonic head tremor in another. DATSCAN-SPECT was abnormal in 3 patients. CONCLUSIONS: Patients with PS may present PD-like parkinsonism with a marked and sustained response to L-Dopa and LID. The characteristic pattern of craniocervical dystonia may be a helpful clue to the diagnosis of PS.

An identical DCTN1 mutation in two Chinese siblings manifest as dHMN and ALS respectively: a case report.

Mutations in the DCTN1 gene have been found in patients with various neurodegenerative diseases, and the spectrum is still expanding. Here, we report a mutation in DCTN1 (c.175G > C, p.G59R) identified in two patients, who manifested dHMN and ALS, respectively, in an affected family. The clinical manifestations and eightyear follow-up suggested that this mutation is pathogenic. The phenomena observed in this family with the same DCTN1 mutation illustrate the clinical heterogeneity of DCTN1 gene mutations and expand our understanding of their genotype-phenotype relationships. Further research and functional experiments, especially mutation at amino acid position 59 of DCTN1, are required.

Spindle cell/sclerosing rhabdomyosarcoma with DCTN1::ALK fusion: broadening the molecular spectrum with potential therapeutic implications.

Spindle cell/sclerosing rbabdomyosarcoma (RMS) is a recently characterized variant of RMS with several distinct molecular subtypes. We describe an example occurring in the tongue of a 10-year-old boy with a novel DCTN1::ALK fusion. The tumor exhibited infiltrative growth and was comprised of fascicles and focally whorls of spindle cells with eosinophilic cytoplasm, in a collagenous or myxoid stroma. Moderate cytologic atypia, mitotic activity (2/10 HPFs), and perineural invasion were identified. The tumor cells expressed actin, desmin, MyoD1, myogenin, and ALK. An in-frame fusion between DCTN1 exon 26 and ALK exon 20 was detected by RNA sequencing, which was confirmed by split reads and supported by FISH studies. The tumor showed an indolent behavior with local recurrence 3 years after excision. This study broadens the molecular spectrum of spindle cell/sclerosing RMS and this molecular aberration may represent a potential therapeutic target for unresectable or disseminated disease.

Perry Syndrome with a Novel Mutation and a Rare Presentation: First Report from India.

Objective: To characterize the first patient of Perry syndrome reported from India. Methods: A 62-year-old gentleman presented with acute encephalopathy, hypercapnia, central hypoventilation, and seizures. He required ventilatory support for persistent respiratory failure even after the resolution of the encephalopathy. History revealed symptoms of orthostatic hypotension, episodes of shallow breathing, unsteadiness of gait, anxiety and depression, and significant weight loss for the previous two years. His mother and elder brother had succumbed to a similar illness. Investigations for neuromuscular diseases, including myasthenia and Pompes disease, were negative. Genetic tests for muscular dystrophies and myopathies, investigations for infectious, autoimmune, and para-neoplastic diseases were negative. Neuroimaging and electrophysiological studies were unremarkable. During his hospital stay, he developed rigidity and bradykinesia. Results: In view of the prominent respiratory failure, Parkinsonism, unexplained weight loss, and family history, he was tested for Perry syndrome. A heterozygous missense variation in Exon 2 of the DCTN1 gene that results in the substitution of Proline for Alanine at codon 45 (pA45P) was detected. This variant was not detected in his clinically unaffected brother. The clinical presentation and genetic test indicate Perry syndrome, a rare autosomal dominant fatal disease, which has never been reported from India. The patient improved with Levodopa and neurorehabilitation but eventually succumbed to his illness three years later. Conclusion: Perry syndrome, though rare, should be considered in the differential diagnosis of patients with a family history of Parkinsonism and central hypoventilation.

Effectiveness of alectinib and osimertinib in a brain metastasized lung adenocarcinoma patient with concurrent EGFR mutations and DCTN1-ALK fusion.

The echinoderm microtubule associated protein-like 4 gene (EML4) encodes the predominant anaplastic lymphoma kinase (ALK) fusion partner in non-small-cell lung cancer (NSCLC); however, the dynactin subunit 1 (DCTN1)-ALK rearrangement is extremely rare. The co-occurrence of primary epidermal growth factor receptor (EGFR) T790M mutation with EGFR exon 19 deletion (del) in patients with NSCLC is uncommon. Here we report a female lung adenocarcinoma patient with brain metastases and possible coexistence of primary EGFR T790M mutation/EGFR exon 19 del/DCTN1-ALK translocation. The patient received multiline treatment including chemotherapy, antivascular, and targeted therapies. To overcome developed resistance to chemotherapy or targeted therapy to prolong overall survival, the patient's circulating tumor DNA (ctDNA) was dynamically monitored. The patient responded to successive osimertinib and alectinib treatment, and alectinib achieved a nearly complete response for lung and brain lesions after she acquired osimertinib resistance. Furthermore, we summarize 22 published cases of patients with lung adenocarcinoma with concurrent EGFR mutation and ALK rearrangement, including details of clinical characteristics, natural history, and pertinent therapy of this uncommon tumor subtype. This literature review shows that EGFR inhibition was an indispensable aspect of the treatment of patients with EGFR/ALK co-alterations in the pre-alectinib era and that ALK inhibition with crizotinib did not show more eye-catching therapeutic results. Considering the effectiveness achieved by alectinib, this case study provides a new perspective for the treatment of lung cancer brain metastasis patients with concurrent EGFR/ALK mutations.

Behavioral profile in a Dctn1G71A knock-in mouse model of Perry disease.

Perry disease (Perry syndrome) is a rare, rapidly progressive, autosomal dominant neurodegenerative disease characterized by parkinsonism, depression/apathy, weight loss, and respiratory symptoms including central hypoventilation. It is caused by missense mutations (e.g. p.G71A) in the DCTN1 gene. We previously generated transgenic mice that expressed human DCTN1G71A mutant protein under the control of Thy1 promoter. These mice exhibited apathy-like behavior and parkinsonism. However, it is possible that this phenotype was due to a gene-dosage imbalance or transgene insertion position. To circumvent these potential caveats, we have generated a knock-in mouse model carrying a p.G71A mutation in Dctn1. Heterozygous Dctn1G71A and wild-type littermates were subjected to a battery of behavioral analyses. Furthermore, immunohistochemistry for tyrosine hydroxylase (TH) was performed on brain sections of these mice, and TH signal intensity in substantia nigral neurons was quantified. Dctn1G71A mice were immobile for longer than wild-type mice of the same age and sex in the tail-suspension test, revealing depressive characteristics. In addition, the beam-walking test and pole test detected motor deficits in Dctn1G71A female mice. Finally, immunostaining revealed a decrease in TH immunoreactivity in neurons of the substantia nigra in the Dctn1G71A mice. Collectively, heterozygous Dctn1G71A mice showed depression-like behavior, motor deficits, and a functional reduction in substantia nigral neurons, as judged by TH immunostaining, thereby exhibiting multiple features of Perry disease. Hence, this mouse model will be useful in elucidating pathological mechanisms of Perry disease and for developing novel therapeutic strategies against it.