Is KIF24 a genetic risk factor for Frontotemporal Lobar Degeneration?

RaphaelHernandezDena G.Van Keuren-JensenKendallShulmanJoshua M.IwakiHirotakaLeonardHampton L.NallsMike A.RobakLaurieBrasJoseGuerreiroRitaLubbeStevenFinkbeinerStevenMencacciNiccolo E.LunguCodrinSingletonAndrew B.ScholzSonja W.ReedXylenaAlcalayRoy N.Gan-OrZivRouleauGuy A.KrohnLynneKrohnLynnevan HiltenJacobus J.MarinusJohanAdarmes-GómezAstrid D.AguilarMiquelAlvarezIgnacioAlvarezVictoriaBarreroFrancisco JavierYarzaJesús Alberto BergarecheBernal-BernalInmaculadaBlazquezMartaBonilla-ToribioMartaBotíaJuan A.BoungiornoMaría TeresaBuiza-RuedaDoloresCarrilloFátimaCarrión-ClaroMarioCerdanDeboraClarimónJordiComptaYaroslauDiez-FairenMonicaDols-IcardoOriolDuarteJacintoDuranRaquelEscamilla-SevillaFranciscoEzquerraMarioFelizCiciFernándezManelFernández-SantiagoRubénGarciaCiaraGarcía-RuizPedroGómez-GarrePilarHerediaMaria Jose GomezGonzalez-AramburuIsabelPagolaAna GorostidiHoenickaJanetInfanteJonJesúsSilviaJimenez-EscrigAdrianoKulisevskyJaimeLabrador-EspinosaMiguel A.Lopez-SendonJose Luisde Munain ArreguiAdolfo LópezMaciasDanielTorresIrene MartínezMarínJuanMartiMaria JoseMartínez-CastrilloJuan CarlosMéndez-del-BarrioCarlotaGonzálezManuel MenéndezMataMarinaMínguezAdolfoMirPabloRezolaElisabet MondragonMuñozEstebanPagonabarragaJavierPastorPauErrazquinFrancisco PerezPeriñán-TocinoTeresaRuiz-MartínezJavierRuzClaraRodriguezAntonio SanchezSierraMaríaSuarez-SanmartinEstherTaberneroCesarTartariJuan PabloTejera-ParradoCristinaTolosaEduardValldeoriolaFrancescVargas-GonzálezLauraVelaLydiaVivesFranciscoZimprichAlexanderPihlstromLasseToftMathiasKoksSulevTabaPilleHassin-BaerSharonMajamaaKariSiitonenAriOkubadejoNjideka U.OjoOluwadamilola O.KaiyrzhanovRauanShashkinChingizZharkynbekovaNaziraAkhmetzhanovVadimAitkulovaAkbotaZholdybayevaElenaZharmukhanovZharkynKaishybayevaGulnazKarimovaAltynaySadykovaDinara, Iacoviello L, Gianfrancesco F, Acampora D, D’Esposito M, Simeone A, Ciullo M, Esposito T. Identification of sixteen novel candidate genes for late onset Parkinson's disease

BACKGROUND

Parkinson's disease (PD) is a neurodegenerative movement disorder affecting 1-5% of the general population for which neither effective cure nor early diagnostic tools are available that could tackle the pathology in the early phase. Here we report a multi-stage procedure to identify candidate genes likely involved in the etiopathogenesis of PD.

METHODS

The study includes a discovery stage based on the analysis of whole exome data from 26 dominant late onset PD families, a validation analysis performed on 1542 independent PD patients and 706 controls from different cohorts and the assessment of polygenic variants load in the Italian cohort (394 unrelated patients and 203 controls).

RESULTS

Family-based approach identified 28 disrupting variants in 26 candidate genes for PD including PARK2, PINK1, DJ-1(PARK7), LRRK2, HTRA2, FBXO7, EIF4G1, DNAJC6, DNAJC13, SNCAIP, AIMP2, CHMP1A, GIPC1, HMOX2, HSPA8, IMMT, KIF21B, KIF24, MAN2C1, RHOT2, SLC25A39, SPTBN1, TMEM175, TOMM22, TVP23A and ZSCAN21. Sixteen of them have not been associated to PD before, were expressed in mesencephalon and were involved in pathways potentially deregulated in PD. Mutation analysis in independent cohorts disclosed a significant excess of highly deleterious variants in cases (p = 0.0001), supporting their role in PD. Moreover, we demonstrated that the co-inheritance of multiple rare variants (≥ 2) in the 26 genes may predict PD occurrence in about 20% of patients, both familial and sporadic cases, with high specificity (> 93%; p = 4.4 × 10- 5). Moreover, our data highlight the fact that the genetic landmarks of late onset PD does not systematically differ between sporadic and familial forms, especially in the case of small nuclear families and underline the importance of rare variants in the genetics of sporadic PD. Furthermore, patients carrying multiple rare variants showed higher risk of manifesting dyskinesia induced by levodopa treatment.

CONCLUSIONS

Besides confirming the extreme genetic heterogeneity of PD, these data provide novel insights into the genetic of the disease and may be relevant for its prediction, diagnosis and treatment.

Frontotemporal dementia

Frontotemporal dementia (FTD) is a neurodegenerative disorder characterized by progressive changes in behavior, personality, and language with involvement of the frontal and temporal regions of the brain. About 40% of FTD cases have a positive family history, and about 10% of these cases are inherited in an autosomal-dominant pattern. These gene defects present with distinct clinical phenotypes. As the diagnosis of FTD becomes more recognizable, it will become increasingly important to keep these gene mutations in mind. In this chapter, we review the genes with known associations to FTD. We discuss protein functions, mutation frequencies, clinical phenotypes, imaging characteristics, and pathology associated with these genes.

Genetics of Frontotemporal Lobar Degeneration: From the Bench to the Clinic

Frontotemporal lobar degeneration (FTLD) is a clinically heterogeneous neurodegenerative disease with a strong genetic component. In this review, we summarize most common mutations in MAPT, GRN, and C90RF72, as well as less common mutations in VCP, CHMP2B, TARDBP, FUS gene and so on. Several guidelines have been developed to help gene testing based on genotype-phenotype correlation, the underlying histopathological subtypes, and the neuroanatomic associations. Furthermore, we also summarize molecular pathways implicated by genes and novel targets for FTLD prevention and management in recent years.

Recent advances in the molecular genetics of frontotemporal lobar degeneration

The term frontotemporal lobar degeneration (FTLD) describes a spectrum of neurodegenerative disorders associated with deposition of misfolded proteins in the frontal and temporal lobes. Up to 40% of FTLD patients reports a family history of neurodegeneration, and approximately 1/3 of familial cases shows an autosomal dominant pattern of inheritance of the phenotype. Over the past two decades, several causative and susceptibility genes for FTLD have been discovered, supporting the notion that genetic factors are important contributors to the disease processes. Genetic variants in three genes, MAPT, GRN and C9orf72, account for about half of familial FTLD cases. In addition, rare defects in the CHMP2B, VCP, TARDBP, SQSTM1, FUS, UBQLN, OPTN, TREM2, CHCHD10 and TBK1 genes have been described. Additional genes are expected to be found in near future. The purpose of this review is to describe recent advances in the molecular genetics of the FTLD spectrum and to discuss implications for genetic counseling.

Chronic PFOS exposure alters the expression of neuronal development-related human homologues in Eisenia fetida

PFOS is a toxic, persistent environmental pollutant which is widespread worldwide. PFOS contamination has entered the food chain and is interfering with normal development in man and is neurotoxic, hepatotoxic and tumorigenic. The earthworm, Eisenia fetida is one of the organisms which can help to diagnose soil health and contamination at lower levels in the food chain. Studying the chronic effects of sub-lethal PFOS exposure in such an organism is therefore appropriate. As PFOS bioaccumulates and is not easily biodegraded, it is biomagnified up the food chain. Gene expression studies will give us information to develop biomarkers for early diagnosis of soil contamination, well before this contaminant passes up the food chain. We have carried out mRNA sequencing of control and chronically PFOS exposed E. fetida and reconstructed the transcripts in silico and identified the differentially expressed genes. Our findings suggest that PFOS up/down regulates neurodegenerative-related human homologues and can cause neuronal damage in E. fetida. This information will help to understand the links between neurodegenerative disorders and environmental pollutants such as PFOS. Furthermore, these up/down regulated genes can be used as biomarkers to detect a sub-lethal presence of PFOS in soil. Neuronal calcium sensor-2, nucleoside diphosphate kinase, polyadenylate-binding protein-1 and mitochondrial Pyruvate dehydrogenase protein-X component, could be potential biomarkers for sub lethal concentrations of PFOS.

Frontotemporal lobar degeneration: current knowledge and future challenges

Frontotemporal lobar degeneration (FTLD) is one of the most frequent neurodegenerative disorders with a presenile onset. It presents with a spectrum of clinical manifestations, ranging from behavioral and executive impairment to language disorders and motor dysfunction. New diagnostic criteria identified two main cognitive syndromes: behavioral variant frontotemporal dementia (bvFTD) and primary progressive aphasia. Regarding bvFTD, new criteria include the use of biomarkers. According to them, bvFTD can be classified in "possible" (clinical features only), "probable" (inclusion of imaging biomarkers) and "definite" (in the presence of a known causal mutation or at autopsy). Familial aggregation is frequently reported in FTLD, and about 10 % of cases have an autosomal dominant transmission. Microtubule-associated protein tau gene mutations have been the first ones identified, and are generally associated with early onset (40-50 years) and with the bvFTD phenotype. More recently, progranulin gene mutations were recognized in association with the familial form of FTLD and a hexanucleotide repetition in C9ORF72 has been shown to be responsible for familial FTLD and amyotrophic lateral sclerosis. In addition, other genes are linked to rare cases of familiar FTLD. Lastly, a number of genetic risk factors for sporadic forms have also been identified.

Genetics of frontotemporal lobar degeneration

Frontotemporal lobar degeneration (FTLD), the most frequent neurodegenerative disorder with a presenile onset, presents with a spectrum of clinical manifestations, ranging from behavioral and executive impairment to language disorders and motor dysfunction. Familial aggregation is frequently reported, and about 10% of cases have an autosomal dominant transmission. Microtubule associated protein tau (MAPT) gene mutations have been the first ones identified and are associated with early onset behavioral variant frontotemporal dementia phenotype. More recently, progranulin gene (GRN) mutations were recognized in association with familial form of FTLD. In addition, other genes are linked to rare cases of familial FTLD. Lastly, a number of genetic risk factors for sporadic forms have also been identified. In this review, current knowledge about mutations at the basis of familial FTLD will be described, together with genetic risk factors influencing the susceptibility to FTLD.