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1.
Genet Sel Evol ; 51(1): 62, 2019 Nov 08.
Artigo em Inglês | MEDLINE | ID: mdl-31703548

RESUMO

BACKGROUND: White spotting of the coat is a characteristic trait of various domestic species including cattle and other mammals. It is a hallmark of Holstein-Friesian cattle, and several previous studies have detected genetic loci with major effects for white spotting in animals with Holstein-Friesian ancestry. Here, our aim was to better understand the underlying genetic and molecular mechanisms of white spotting, by conducting the largest mapping study for this trait in cattle, to date. RESULTS: Using imputed whole-genome sequence data, we conducted a genome-wide association analysis in 2973 mixed-breed cows and bulls. Highly significant quantitative trait loci (QTL) were found on chromosomes 6 and 22, highlighting the well-established coat color genes KIT and MITF as likely responsible for these effects. These results are in broad agreement with previous studies, although we also report a third significant QTL on chromosome 2 that appears to be novel. This signal maps immediately adjacent to the PAX3 gene, which encodes a known transcription factor that controls MITF expression and is the causal locus for white spotting in horses. More detailed examination of these loci revealed a candidate causal mutation in PAX3 (p.Thr424Met), and another candidate mutation (rs209784468) within a conserved element in intron 2 of MITF transcripts expressed in the skin. These analyses also revealed a mechanistic ambiguity at the chromosome 6 locus, where highly dispersed association signals suggested multiple or multiallelic QTL involving KIT and/or other genes in this region. CONCLUSIONS: Our findings extend those of previous studies that reported KIT as a likely causal gene for white spotting, and report novel associations between candidate causal mutations in both the MITF and PAX3 genes. The sizes of the effects of these QTL are substantial, and could be used to select animals with darker, or conversely whiter, coats depending on the desired characteristics.

2.
Sci Rep ; 9(1): 16934, 2019 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-31729446

RESUMO

The popularisation and decreased cost of genome resequencing has resulted in an increased use in molecular diagnostics. While there are a number of established and high quality bioinfomatic tools for identifying small genetic variants including single nucleotide variants and indels, currently there is no established standard for the detection of copy number variants (CNVs) from sequence data. The requirement for CNV detection from high throughput sequencing has resulted in the development of a large number of software packages. These tools typically utilise the sequence data characteristics: read depth, split reads, read pairs, and assembly-based techniques. However, the additional source of information from read balance (defined as relative proportion of reads of each allele at each position) has been underutilised in the existing applications. Here we present Read Balance Validator (RBV), a bioinformatic tool that uses read balance for prioritisation and validation of putative CNVs. The software simultaneously interrogates nominated regions for the presence of deletions or multiplications, and can differentiate larger CNVs from diploid regions. Additionally, the utility of RBV to test for inheritance of CNVs is demonstrated in this report. RBV is a CNV validation and prioritisation bioinformatic tool for both genome and exome sequencing available as a python package from https://github.com/whitneywhitford/RBV.

3.
Elife ; 82019 08 15.
Artigo em Inglês | MEDLINE | ID: mdl-31414984

RESUMO

Innovations in metazoan development arise from evolutionary modification of gene regulatory networks (GRNs). We report widespread cryptic variation in the requirement for two key regulatory inputs, SKN-1/Nrf2 and MOM-2/Wnt, into the C. elegans endoderm GRN. While some natural isolates show a nearly absolute requirement for these two regulators, in others, most embryos differentiate endoderm in their absence. GWAS and analysis of recombinant inbred lines reveal multiple genetic regions underlying this broad phenotypic variation. We observe a reciprocal trend, in which genomic variants, or knockdown of endoderm regulatory genes, that result in a high SKN-1 requirement often show low MOM-2/Wnt requirement and vice-versa, suggesting that cryptic variation in the endoderm GRN may be tuned by opposing requirements for these two key regulatory inputs. These findings reveal that while the downstream components in the endoderm GRN are common across metazoan phylogeny, initiating regulatory inputs are remarkably plastic even within a single species.


Assuntos
Proteínas de Caenorhabditis elegans/biossíntese , Caenorhabditis elegans/crescimento & desenvolvimento , Regulação da Expressão Gênica no Desenvolvimento , Redes Reguladoras de Genes , Progranulinas/biossíntese , Animais , Proteínas de Caenorhabditis elegans/genética , Proteínas de Caenorhabditis elegans/metabolismo , Proteínas de Ligação a DNA/metabolismo , Variação Genética , Peptídeos e Proteínas de Sinalização Intracelular/metabolismo , Fatores de Transcrição/metabolismo , Proteínas Wnt/metabolismo
4.
Metabolites ; 9(6)2019 Jun 11.
Artigo em Inglês | MEDLINE | ID: mdl-31212603

RESUMO

Huntington's disease (HD) is a neurodegenerative disorder caused by an expanded CAG repeat in exon 1 of the HTT gene. HD usually manifests in mid-life with loss of GABAergic projection neurons from the striatum accompanied by progressive atrophy of the putamen followed by other brain regions, but linkages between the genetics and neurodegeneration are not understood. We measured metabolic perturbations in HD-human brain in a case-control study, identifying pervasive lowering of vitamin B5, the obligatory precursor of coenzyme A (CoA) that is essential for normal intermediary metabolism. Cerebral pantothenate deficiency is a newly-identified metabolic defect in human HD that could potentially: (i) impair neuronal CoA biosynthesis; (ii) stimulate polyol-pathway activity; (iii) impair glycolysis and tricarboxylic acid cycle activity; and (iv) modify brain-urea metabolism. Pantothenate deficiency could lead to neurodegeneration/dementia in HD that might be preventable by treatment with vitamin B5.

5.
J Biomed Inform ; 94: 103174, 2019 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-30965134

RESUMO

BACKGROUND: Whole genome sequencing (WGS) has increased in popularity and decreased in cost over the past decade, rendering this approach as a viable and sensitive method for variant detection. In addition to its utility for single nucleotide variant detection, WGS data has the potential to detect Copy Number Variants (CNV) to fine resolution. Many CNV detection software packages have been developed exploiting four main types of data: read pair, split read, read depth, and assembly based methods. The aim of this study was to evaluate the efficiency of each of these main approaches in detecting germline deletions. METHODS: WGS data and high confidence deletion calls for the individual NA12878 from the Genome in a Bottle consortium were the benchmark dataset. The performance of BreakDancer, CNVnator, Delly, FermiKit, and Pindel was assessed by comparing the accuracy and sensitivity of each software package in detecting deletions exceeding 1 kb. RESULTS: There was considerable variability in the outputs of the different WGS CNV detection programs. The best performance was seen from BreakDancer and Delly, with 92.6% and 96.7% sensitivity, respectively and 34.5% and 68.5% false discovery rate (FDR), respectively. In comparison, Pindel, CNVnator, and FermiKit were less effective with sensitivities of 69.1%, 66.0%, and 15.8%, respectively and FDR of 91.3%, 69.0%, and 31.7%, respectively. Concordance across software packages was poor, with only 27 of the total 612 benchmark deletions identified by all five methodologies. CONCLUSIONS: The WGS based CNV detection tools evaluated show disparate performance in identifying deletions ≥1 kb, particularly those utilising different input data characteristics. Software that exploits read pair based data had the highest sensitivity, namely BreakDancer and Delly. BreakDancer also had the second lowest false discovery rate. Therefore, in this analysis read pair methods (BreakDancer in particular) were the best performing approaches for the identification of deletions ≥1 kb, balancing accuracy and sensitivity. There is potential for improvement in the detection algorithms, particularly for reducing FDR. This analysis has validated the utility of WGS based CNV detection software to reliably identify deletions, and these findings will be of use when choosing appropriate software for deletion detection, in both research and diagnostic medicine.

6.
Genet Sel Evol ; 51(1): 3, 2019 Jan 24.
Artigo em Inglês | MEDLINE | ID: mdl-30678637

RESUMO

BACKGROUND: Over many years, artificial selection has substantially improved milk production by cows. However, the genes that underlie milk production quantitative trait loci (QTL) remain relatively poorly characterised. Here, we investigate a previously reported QTL located at the CSF2RB locus on chromosome 5, for several milk production phenotypes, to better understand its underlying genetic and molecular causes. RESULTS: Using a population of 29,350 taurine dairy cows, we conducted association analyses for milk yield and composition traits, and identified highly significant QTL for milk yield, milk fat concentration, and milk protein concentration. Strikingly, protein concentration and milk yield appear to show co-located yet genetically distinct QTL. To attempt to understand the molecular mechanisms that might be mediating these effects, gene expression data were used to investigate eQTL for 11 genes in the broader interval. This analysis highlighted genetic impacts on CSF2RB and NCF4 expression that share similar association signatures to those observed for lactation QTL, strongly implicating one or both of these genes as responsible for these effects. Using the same gene expression dataset representing 357 lactating cows, we also identified 38 novel RNA editing sites in the 3' UTR of CSF2RB transcripts. The extent to which two of these sites were edited also appears to be genetically co-regulated with lactation QTL, highlighting a further layer of regulatory complexity that involves the CSF2RB gene. CONCLUSIONS: This locus presents a diversity of molecular and lactation QTL, likely representing multiple overlapping effects that, at a minimum, highlight the CSF2RB gene as having a causal role in these processes.


Assuntos
Bovinos/genética , Subunidade beta Comum dos Receptores de Citocinas/genética , Lactação/genética , Fenótipo , Locos de Características Quantitativas , Regiões 3' não Traduzidas , Animais , Subunidade beta Comum dos Receptores de Citocinas/metabolismo , Feminino , Masculino , Leite/metabolismo , Fosfoproteínas/genética
7.
J Chem Neuroanat ; 97: 43-56, 2019 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-30664938

RESUMO

The substantia nigra is an integral component of the basal ganglia circuitry for limbic and motor functions. Dysfunction and degeneration of the basal ganglia are fundamental aspects of neurodegenerative diseases such as Parkinson's disease and Huntington's disease. With the increasing use of sheep to model neurological diseases, it is crucial to understand the anatomy and neurochemistry of these key basal ganglia nuclei in the normal sheep brain and how they compare to the human brain. Therefore, studies of the gross anatomy, cellular morphology, and neurochemical expression patterns within the sheep substantia nigra were performed. We show that the sheep substantia nigra reflects all important aspects of the anatomy and neurochemistry of the human substantia nigra, with only minor inter-species differences evident. Many neurochemicals that are central to the functioning of the SN, and wider basal ganglia circuitry, are present throughout the sheep SN. In a wider context, the results of this study provide evidence that the sheep substantia nigra accurately reflects the anatomy of the human substantia nigra, which validates the use of sheep models of basal ganglia neurological disorders.

8.
RNA ; 25(3): 319-335, 2019 03.
Artigo em Inglês | MEDLINE | ID: mdl-30530731

RESUMO

Post-transcriptional RNA editing may regulate transcript expression and diversity in cells, with potential impacts on various aspects of physiology and environmental adaptation. A small number of recent genome-wide studies in Drosophila, mouse, and human have shown that RNA editing can be genetically modulated, highlighting loci that quantitatively impact editing of transcripts. The potential gene expression and physiological consequences of these RNA-editing quantitative trait loci (edQTL), however, are almost entirely unknown. Here, we present analyses of RNA editing in a large domestic mammal (Bos taurus), where we use whole-genome and high-depth RNA sequencing to discover, characterize, and conduct genetic mapping studies of novel transcript edits. Using a discovery population of nine deeply sequenced cows, we identify 2413 edit sites in the mammary transcriptome, the majority of which are adenosine to inosine edits (98.6%). Most sites are predicted to reside in double-stranded secondary structures (85.1%), and quantification of the rates of editing in an additional 355 cows reveals editing is negatively correlated with gene expression in the majority of cases. Genetic analyses of RNA editing and gene expression highlight 152 cis-regulated edQTL, of which 15 appear to cosegregate with expression QTL effects. Trait association analyses in a separate population of 9989 lactating cows also shows 12 of the cis-edQTL coincide with at least one cosegregating lactation QTL. Together, these results enhance our understanding of RNA-editing dynamics in mammals, and suggest mechanistic links by which loci may impact phenotype through RNA editing mediated processes.


Assuntos
Regulação da Expressão Gênica , Mamíferos/genética , Edição de RNA , Animais , Sequência de Bases , Mapeamento Cromossômico , Biologia Computacional/métodos , Sequência Consenso , Estudo de Associação Genômica Ampla , Sequenciamento de Nucleotídeos em Larga Escala , Humanos , Locos de Características Quantitativas , Característica Quantitativa Herdável
9.
Mol Genet Genomic Med ; 7(1): e00476, 2019 01.
Artigo em Inglês | MEDLINE | ID: mdl-30345660

RESUMO

BACKGROUND: Isolated cardiac arrhythmia due to a variant in CACNA1C is of recent knowledge. Most reports have been of singleton cases or of quite small families, and estimates of penetrance and expressivity have been difficult to obtain. We here describe a large pedigree, from which such estimates have been calculated. METHODS: We studied a five-generation family, in which a CACNA1C variant c.2573G>A p.Arg858His co-segregates with syncope and cardiac arrest, documenting electrocardiographic data and cardiac symptomatology. The reported patients/families from the literature with CACNA1C gene variants were reviewed, and genotype-phenotype correlations are drawn. RESULTS: The range of phenotype in the studied family is wide, from no apparent effect, through an asymptomatic QT interval prolongation on electrocardiography, to episodes of presyncope and syncope, ventricular fibrillation, and sudden death. QT prolongation showed inconsistent correlation with functional cardiology. Based upon analysis of 28 heterozygous family members, estimates of penetrance and expressivity are derived. CONCLUSIONS: These estimates of penetrance and expressivity, for this specific variant, may be useful in clinical practice. Review of the literature indicates that individual CACNA1C variants have their own particular genotype-phenotype correlations. We suggest that, at least in respect of the particular variant reported here, "arrhythmogenic channelopathy" may be a more fitting nomenclature than long QT syndrome.


Assuntos
Arritmias Cardíacas/genética , Canais de Cálcio Tipo L/genética , Canalopatias/genética , Mutação de Sentido Incorreto , Penetrância , Adulto , Idoso , Arritmias Cardíacas/patologia , Canalopatias/patologia , Criança , Eletrocardiografia , Feminino , Genótipo , Heterozigoto , Humanos , Lactente , Masculino , Pessoa de Meia-Idade , Linhagem , Fenótipo
10.
Dis Model Mech ; 11(11)2018 11 09.
Artigo em Inglês | MEDLINE | ID: mdl-30266839

RESUMO

Brain dopamine-serotonin vesicular transport disease is a rare disease caused by autosomal recessive mutations in the SLC18A2 gene, which encodes the VMAT2 protein. VMAT2 is a membrane protein responsible for vesicular transport of monoamines, and its disruption negatively affects neurotransmission. This results in a severe neurodevelopmental disorder affecting motor skills and development, and causes muscular hypotonia. The condition was initially described in a consanguineous Saudi Arabian family with affected siblings homozygous for a P387L mutation. We subsequently found a second mutation in a New Zealand family (homozygous P237H), which was later also identified in an Iraqi family. Pramipexole has been shown to have some therapeutic benefit. Transgenic Caenorhabditis elegans were developed to model the P237H and P387L mutations. Investigations into dopamine- and serotonin-related C. elegans phenotypes, including pharyngeal pumping and grazing, showed that both mutations cause significant impairment of these processes when compared with a non-transgenic N2 strain and a transgenic containing the wild-type human SLC18A2 gene. Preliminary experiments investigating the therapeutic effects of serotonin and pramipexole demonstrated that serotonin could successfully restore the pharyngeal pumping phenotype. These analyses provide further support for the role of these mutations in this disease.


Assuntos
Encéfalo/metabolismo , Caenorhabditis elegans/metabolismo , Dopamina/metabolismo , Modelos Biológicos , Serotonina/metabolismo , Vesículas Transportadoras/patologia , Animais , Animais Geneticamente Modificados , Sequência de Bases , Transporte Biológico , Humanos , Faringe/patologia , Fenótipo , Vesículas Transportadoras/metabolismo
11.
N Z Med J ; 131(1480): 81-89, 2018 08 17.
Artigo em Inglês | MEDLINE | ID: mdl-30116069

RESUMO

Precision medicine seeks to draw on data from both individuals and populations across disparate domains to influence and support diagnosis, management and prevention in healthcare at the level of the individual patient and their family/whanau. Central to this initiative is incorporating the effects of the inherent variation that lies within genomes and can influence health outcomes. Identifying and interpreting such variation requires an accurate, valid and representative dataset to firstly define what variants are present and then assess the potential relevance for the health of a person, their family/whanau and the wider community to which they belong. Globally the variation embedded within genomes differs enormously and has been shaped by the size, constitution, historical origins and evolutionary history of their source populations. Maori, and more broadly Pacific peoples, differ substantially in terms of genomic variation compared to the more closely studied European and Asian populations. In the absence of accurate genomic information from Maori and Pacific populations, the precise interpretation of genomic data and the success and benefits of genomic medicine will be disproportionately less for those Maori and Pacific peoples. In this viewpoint article we, as a group of healthcare professionals, researchers and scientists, present a case for assembling genomic resources that catalogue the characteristics of the genomes of New Zealanders, with an emphasis on peoples of Maori and Polynesian ancestry, as a healthcare imperative. In proposing the creation of these resources, we note that their governance and management must be led by iwi and Maori and Pacific representatives. Assembling a genomic resource must be informed by cultural concepts and values most especially understanding that, at a physical and spiritual level, whakapapa is embodied within the DNA of a person. Therefore DNA and genomic data that connects to whakapapa (genealogy) is considered a taonga (something precious and significant), and its storage, utilisation and interpretation is a culturally significant activity. Furthermore, such resources are not proposed to primarily enable comparisons between those with Maori and broader Pacific ancestries and other Aotearoa peoples but to place an understanding of the genetic contributors to their health outcomes in a valid context. Ongoing oversight and governance of such taonga by Maori and Pacific representatives will maximise hauora (health) while also minimising the risk of misuse of this information.


Assuntos
Genômica , Disparidades em Assistência à Saúde/etnologia , Medicina de Precisão , Genética Médica , Humanos , Nova Zelândia/etnologia , Grupo com Ancestrais Oceânicos/genética
12.
J Dairy Res ; 85(2): 185-192, 2018 May.
Artigo em Inglês | MEDLINE | ID: mdl-29785904

RESUMO

Inflammation of the mammary gland following bacterial infection, commonly known as mastitis, affects all mammalian species. Although the aetiology and epidemiology of mastitis in the dairy cow are well described, the genetic factors mediating resistance to mammary gland infection are not well known, due in part to the difficulty in obtaining robust phenotypic information from sufficiently large numbers of individuals. To address this problem, an experimental mammary gland infection experiment was undertaken, using a Friesian-Jersey cross breed F2 herd. A total of 604 animals received an intramammary infusion of Streptococcus uberis in one gland, and the clinical response over 13 milkings was used for linkage mapping and genome-wide association analysis. A quantitative trait locus (QTL) was detected on bovine chromosome 11 for clinical mastitis status using micro-satellite and Affymetrix 10 K SNP markers, and then exome and genome sequence data used from the six F1 sires of the experimental animals to examine this region in more detail. A total of 485 sequence variants were typed in the QTL interval, and association mapping using these and an additional 37 986 genome-wide markers from the Illumina SNP50 bovine SNP panel revealed association with markers encompassing the interleukin-1 gene cluster locus. This study highlights a region on bovine chromosome 11, consistent with earlier studies, as conferring resistance to experimentally induced mammary gland infection, and newly prioritises the IL1 gene cluster for further analysis in genetic resistance to mastitis.


Assuntos
Mastite Bovina/genética , Mastite Bovina/imunologia , Infecções Estreptocócicas/veterinária , Animais , Bovinos , Mapeamento Cromossômico/veterinária , Modelos Animais de Doenças , Feminino , Predisposição Genética para Doença , Variação Genética , Estudo de Associação Genômica Ampla/veterinária , Genótipo , Hibridização Genética , Mastite Bovina/microbiologia , Polimorfismo de Nucleotídeo Único , Locos de Características Quantitativas/genética
14.
JIMD Rep ; 42: 31-36, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-29159460

RESUMO

Autosomal recessive ataxias are characterised by a fundamental loss in coordination of gait with associated atrophy of the cerebellum. There is significant clinical and genetic heterogeneity amongst inherited ataxias; however, an early molecular diagnosis is essential with low-risk treatments available for some of these conditions. We describe two female siblings who presented early in life with unsteady gait and cerebellar atrophy. Whole exome sequencing revealed compound heterozygous inheritance of two pathogenic mutations (p.Leu277Pro, c.1506+1G>A) in the coenzyme Q8A gene (COQ8A), a gene central to biosynthesis of coenzyme Q (CoQ). The paternally derived p.Leu277Pro mutation is predicted to disrupt a conserved motif in the substrate-binding pocket of the protein, resulting in inhibition of CoQ10 production. The maternal c.1506+1G>A mutation destroys a canonical splice donor site in exon 12 affecting transcript processing and subsequent protein translation. Mutations in this gene can result in primary coenzyme Q10 deficiency type 4, which is characterized by childhood onset of cerebellar ataxia and exercise intolerance, both of which were observed in this sib-pair. Muscle biopsies revealed unequivocally low levels of CoQ10, and the siblings were subsequently established on a therapeutic dose of CoQ10 with distinct clinical evidence of improvement after 1 year of treatment. This case emphasises the importance of an early and accurate molecular diagnosis for suspected inherited ataxias, particularly given the availability of approved treatments for some subtypes.

15.
BMC Genomics ; 18(1): 968, 2017 Dec 15.
Artigo em Inglês | MEDLINE | ID: mdl-29246110

RESUMO

BACKGROUND: Lactose provides an easily-digested energy source for neonates, and is the primary carbohydrate in milk in most species. Bovine lactose is also a key component of many human food products. However, compared to analyses of other milk components, the genetic control of lactose has been little studied. Here we present the first GWAS focussed on analysis of milk lactose traits. RESULTS: Using a discovery population of 12,000 taurine dairy cattle, we detail 27 QTL for lactose concentration and yield, and subsequently validate the effects of 26 of these loci in a distinct population of 18,000 cows. We next present data implicating causative genes and variants for these QTL. Fine mapping of these regions using imputed, whole genome sequence-resolution genotypes reveals protein-coding candidate causative variants affecting the ABCG2, DGAT1, STAT5B, KCNH4, NPFFR2 and RNF214 genes. Eleven of the remaining QTL appear to be driven by regulatory effects, suggested by the presence of co-locating, co-segregating eQTL discovered using mammary RNA sequence data from a population of 357 lactating cows. Pathway analysis of genes representing all lactose-associated loci shows significant enrichment of genes located in the endoplasmic reticulum, with functions related to ion channel activity mediated through the LRRC8C, P2RX4, KCNJ2 and ANKH genes. A number of the validated QTL are also found to be associated with additional milk volume, fat and protein phenotypes. CONCLUSIONS: Overall, these findings highlight novel candidate genes and variants involved in milk lactose regulation, whose impacts on membrane transport mechanisms reinforce the key osmo-regulatory roles of lactose in milk.


Assuntos
Lactose/metabolismo , Proteínas de Membrana Transportadoras/genética , Leite/metabolismo , Locos de Características Quantitativas , Alelos , Animais , Bovinos , Feminino , Expressão Gênica , Variação Genética , Estudo de Associação Genômica Ampla , Transporte de Íons/genética , Lactação/genética , Fenótipo , Polimorfismo de Nucleotídeo Único , Análise de Sequência de DNA , Análise de Sequência de RNA
16.
Proc Natl Acad Sci U S A ; 114(52): E11293-E11302, 2017 12 26.
Artigo em Inglês | MEDLINE | ID: mdl-29229845

RESUMO

The neurodegenerative disorder Huntington's disease (HD) is typically characterized by extensive loss of striatal neurons and the midlife onset of debilitating and progressive chorea, dementia, and psychological disturbance. HD is caused by a CAG repeat expansion in the Huntingtin (HTT) gene, translating to an elongated glutamine tract in the huntingtin protein. The pathogenic mechanism resulting in cell dysfunction and death beyond the causative mutation is not well defined. To further delineate the early molecular events in HD, we performed RNA-sequencing (RNA-seq) on striatal tissue from a cohort of 5-y-old OVT73-line sheep expressing a human CAG-expansion HTT cDNA transgene. Our HD OVT73 sheep are a prodromal model and exhibit minimal pathology and no detectable neuronal loss. We identified significantly increased levels of the urea transporter SLC14A1 in the OVT73 striatum, along with other important osmotic regulators. Further investigation revealed elevated levels of the metabolite urea in the OVT73 striatum and cerebellum, consistent with our recently published observation of increased urea in postmortem human brain from HD cases. Extending that finding, we demonstrate that postmortem human brain urea levels are elevated in a larger cohort of HD cases, including those with low-level neuropathology (Vonsattel grade 0/1). This elevation indicates increased protein catabolism, possibly as an alternate energy source given the generalized metabolic defect in HD. Increased urea and ammonia levels due to dysregulation of the urea cycle are known to cause neurologic impairment. Taken together, our findings indicate that aberrant urea metabolism could be the primary biochemical disruption initiating neuropathogenesis in HD.


Assuntos
Corpo Estriado/metabolismo , Doença de Huntington/metabolismo , Ureia/metabolismo , Adulto , Animais , Animais Geneticamente Modificados , Corpo Estriado/patologia , Modelos Animais de Doenças , Feminino , Humanos , Proteína Huntingtina/genética , Proteína Huntingtina/metabolismo , Doença de Huntington/genética , Doença de Huntington/patologia , Masculino , Ovinos , Expansão das Repetições de Trinucleotídeos/genética
17.
Adv Neurobiol ; 15: 129-161, 2017.
Artigo em Inglês | MEDLINE | ID: mdl-28674980

RESUMO

Huntington's disease (HD) is an autosomal dominant neurodegenerative disorder characterised by extensive neuronal loss in the striatum and cerebral cortex, and a triad of clinical symptoms affecting motor, cognitive/behavioural and mood functioning. The mutation causing HD is an expansion of a CAG tract in exon 1 of the HTT gene. This chapter provides a multifaceted overview of the clinical complexity of HD. We explore recent directions in molecular genetics including the identification of loci that are genetic modifiers of HD that could potentially reveal therapeutic targets beyond the HTT gene transcript and protein. The variability of clinical symptomatology in HD is considered alongside recent findings of variability in cellular and neurochemical changes in the striatum and cerebral cortex in human brain. We review evidence from structural neuroimaging methods of progressive changes of striatum, cerebral cortex and white matter in pre-symptomatic and symptomatic HD, with a particular focus on the potential identification of neuroimaging biomarkers that could be used to test promising disease-specific and modifying treatments. Finally we provide an overview of completed clinical trials in HD and future therapeutic developments.


Assuntos
Córtex Cerebral/metabolismo , Corpo Estriado/metabolismo , Genes Modificadores/genética , Proteína Huntingtina/genética , Doença de Huntington/genética , Afeto , Córtex Cerebral/diagnóstico por imagem , Cognição , Transtornos Cognitivos/fisiopatologia , Corpo Estriado/diagnóstico por imagem , Humanos , Doença de Huntington/diagnóstico por imagem , Doença de Huntington/fisiopatologia , Doença de Huntington/psicologia , Transtornos Mentais/fisiopatologia , Biologia Molecular , Terapia de Alvo Molecular , Movimento , Transtornos dos Movimentos/fisiopatologia , Neuroimagem
18.
Artigo em Inglês | MEDLINE | ID: mdl-28696212

RESUMO

Mutations in the gene SLC19A3 result in thiamine metabolism dysfunction syndrome 2, also known as biotin-thiamine-responsive basal ganglia disease (BTBGD). This neurometabolic disease typically presents in early childhood with progressive neurodegeneration, including confusion, seizures, and dysphagia, advancing to coma and death. Treatment is possible via supplement of biotin and/or thiamine, with early treatment resulting in significant lifelong improvements. Here we report two siblings who received a refined diagnosis of BTBGD following whole-genome sequencing. Both children inherited compound heterozygous mutations from unaffected parents; a missense single-nucleotide variant (p.G23V) in the first transmembrane domain of the protein, and a 4808-bp deletion in exon 1 encompassing the 5' UTR and minimal promoter region. This deletion is the smallest promoter deletion reported to date, further defining the minimal promoter region of SLC19A3 Unfortunately, one of the siblings died prior to diagnosis, but the other is showing significant improvement after commencement of therapy. This case demonstrates the power of whole-genome sequencing for the identification of structural variants and subsequent diagnosis of rare neurodevelopmental disorders.


Assuntos
Doenças dos Gânglios da Base/genética , Proteínas de Membrana Transportadoras/genética , Regiões 5' não Traduzidas/genética , Gânglios da Base/metabolismo , Doenças dos Gânglios da Base/diagnóstico , Biotina/genética , Biotina/metabolismo , Encéfalo/metabolismo , Criança , Feminino , Humanos , Imagem por Ressonância Magnética , Masculino , Proteínas de Membrana Transportadoras/metabolismo , Mutação , Regiões Promotoras Genéticas/genética , Irmãos , Tiamina/metabolismo , Adulto Jovem
19.
Neurobiol Aging ; 58: 112-119, 2017 10.
Artigo em Inglês | MEDLINE | ID: mdl-28728117

RESUMO

This study reports the identification and characterization of markers of Alzheimer's disease (AD) in aged sheep (Ovis aries) as a preliminary step toward making a genetically modified large animal model of AD. Importantly, the sequences of key proteins involved in AD pathogenesis are highly conserved between sheep and human. The processing of the amyloid-ß (Aß) protein is conserved between sheep and human, and sheep Aß1-42/Aß1-40 ratios in cerebrospinal fluid (CSF) are also very similar to human. In addition, total tau and neurofilament light levels in CSF are comparable with those found in human. The presence of neurofibrillary tangles in aged sheep brain has previously been established; here, we report for the first time that plaques, the other pathologic hallmark of AD, are also present in the aged sheep brain. In summary, the biological machinery to generate the key neuropathologic features of AD is conserved between the human and sheep, making the sheep a good candidate for future genetic manipulation to accelerate the condition for use in pathophysiological discovery and therapeutic testing.


Assuntos
Doença de Alzheimer , Peptídeos beta-Amiloides/líquido cefalorraquidiano , Animais Geneticamente Modificados , Modelos Animais de Doenças , Proteínas de Neurofilamentos/líquido cefalorraquidiano , Fragmentos de Peptídeos/líquido cefalorraquidiano , Proteínas tau/líquido cefalorraquidiano , Doença de Alzheimer/diagnóstico , Doença de Alzheimer/metabolismo , Doença de Alzheimer/patologia , Animais , Biomarcadores/líquido cefalorraquidiano , Encéfalo/metabolismo , Encéfalo/patologia , Humanos , Emaranhados Neurofibrilares , Placa Amiloide/metabolismo , Placa Amiloide/patologia , Ovinos
20.
Sci Rep ; 7: 44793, 2017 03 21.
Artigo em Inglês | MEDLINE | ID: mdl-28322319

RESUMO

A major pleiotropic quantitative trait locus (QTL) located at ~25 Mbp on bovine chromosome 14 affects a myriad of growth and developmental traits in Bos taurus and indicus breeds. These QTL have been attributed to two functional variants in the bidirectional promoter of PLAG1 and CHCHD7. Although PLAG1 is a good candidate for mediating these effects, its role remains uncertain given that these variants are also associated with expression of five additional genes at the broader locus. In the current study, we conducted expression QTL (eQTL) mapping of this region using a large, high depth mammary RNAseq dataset representing 375 lactating cows. Here we show that of the seven previously implicated genes, only PLAG1 and LYN are differentially expressed by QTL genotype, and only PLAG1 bears the same association signature of the growth and body weight QTLs. For the first time, we also report significant association of PLAG1 genotype with milk production traits, including milk fat, volume, and protein yield. Collectively, these data strongly suggest PLAG1 as the causative gene underlying this diverse range of traits, and demonstrate new effects for the locus on lactation phenotypes.


Assuntos
Peso Corporal/genética , Bovinos/genética , Proteínas de Ligação a DNA/genética , Pleiotropia Genética , Leite/química , Animais , Cromossomos de Mamíferos/genética , Indústria de Laticínios , Regulação da Expressão Gênica , Estudo de Associação Genômica Ampla , Polimorfismo de Nucleotídeo Único/genética , Locos de Características Quantitativas/genética , Característica Quantitativa Herdável , Reprodutibilidade dos Testes
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