The increasing transparence of the human genome has profound implications for how we understand health and illness and perceive our biological and social relatedness to others. Presymptomatic testing for adult onset conditions, in particular, creates the novel situation in which some individuals know in advance of impending illness while others learn that they have escaped such a fate. How families at risk for one adult onset condition — Huntington Disease (HD) — communicate about such information is the topic of this dissertation. HD is often described as a 'genetic time bomb'. It is an autosomal dominant neuropsychiatric disorder characterized by mid-life onset, involuntary movements, cognitive impairment, and depression. There is no effective prevention or cure but with the advent of predictive testing in 1987 it became possible for at risk individuals to learn if they had inherited the mutation associated with HL\ Empirical studies on predictive testing for HD focus primarily on the individual psychological impacts of the test; few studies consider how families understand and attempt to manage genetic information in their everyday lives. This dissertation begins to address these lacunae by examining the stories that test candidates and their families tell about hereditary risk and predictive testing. These stories derive from a prospectively designed study which includes 102 in-depth, at-home interviews conducted in the pre and post-results period with 16 test candidates and 33 family members. Focusing on three narrative 'moments', the dissertation explores how study participants storied their experiences of: 1) learning about the family history of HD, 2) deciding to request the predictive test and, 3) making sense of an informative result. Drawing upon a social constructionist approach, the analysis emphasizes the processual nature of predictive testing as well as the significance of interpersonal communication in producing and reproducing the social realities in which genetic information acquires a particular salience. Given the recent proliferation of genetic tests as well as the absence of an adequate popular discourse on embodied risk, the research underscores lay actors' abilities to reframe existing clinical schema in order to interpret and manage hereditary risk in an intersubjectively meaningful way.

The increasing transparence of the human genome has profound implications for how we understand health and illness and perceive our biological and social relatedness to others. Presymptomatic testing for adult onset conditions, in particular, creates the novel situation in which some individuals know in advance of impending illness while others learn that they have escaped such a fate. How families at risk for one adult onset condition — Huntington Disease (HD) — communicate about such information is the topic of this dissertation. HD is often described as a 'genetic time bomb'. It is an autosomal dominant neuropsychiatric disorder characterized by mid-life onset, involuntary movements, cognitive impairment, and depression. There is no effective prevention or cure but with the advent of predictive testing in 1987 it became possible for at risk individuals to learn if they had inherited the mutation associated with HL\ Empirical studies on predictive testing for HD focus primarily on the individual psychological impacts of the test; few studies consider how families understand and attempt to manage genetic information in their everyday lives. This dissertation begins to address these lacunae by examining the stories that test candidates and their families tell about hereditary risk and predictive testing. These stories derive from a prospectively designed study which includes 102 in-depth, at-home interviews conducted in the pre and post-results period with 16 test candidates and 33 family members. Focusing on three narrative 'moments', the dissertation explores how study participants storied their experiences of: 1) learning about the family history of HD, 2) deciding to request the predictive test and, 3) making sense of an informative result. Drawing upon a social constructionist approach, the analysis emphasizes the processual nature of predictive testing as well as the significance of interpersonal communication in producing and reproducing the social realities in which genetic information acquires a particular salience. Given the recent proliferation of genetic tests as well as the absence of an adequate popular discourse on embodied risk, the research underscores lay actors' abilities to reframe existing clinical schema in order to interpret and manage hereditary risk in an intersubjectively meaningful way. / Arts, Faculty of / Anthropology, Department of / Graduate

Chorea Huntington (HD) ist eine neurodegenerative Erkrankung, die durch Ablagerungen von N-terminal Polyglutamin-reichen Huntingtin (Htt) -Fragmenten in den betroffenen Neuronen charakterisiert ist. Das mutierte Htt (mHtt) Protein wird ubiquitär exprimiert. Das zellspezifische Absterben von „medium-sized spiny neurons“ (MSN) wird jedoch im Striatum von HD Patienten verursacht (Albin, 1995). Es wird angenommen, dass Striatum-spezifische Proteine, die mit Htt interagieren, eine wichtige Rolle in der Pathogenese von HD spielen (Ross, 1995). Protein-Protein-Interaktionsstudien haben gezeigt, dass einige der Htt-Interaktionspartner mit unlöslichen Htt-Ablagerungen in den Gehirnen von HD-Patienten kolokalisieren und die Bildung von Protein-Aggregaten beeinflussen (Goehler, 2004). Kürzlich wurde durch die Integration von Genexpressions- und Interaktionsdaten ein Striatum-spezifisches Protein-Interaktionsnetzwerk erstellt (Chaurasia, unveröffentlichte Daten). Eines der identifizierten Proteine ist CRMP1 (collapsin response mediator protein 1), das spezifisch in Neuronen exprimiert wird und möglicherweise eine wichtige Rolle bei der Pathogenese von HD spielt. Experimentelle Untersuchungen mithilfe eines Filter-Retardationsassays zeigten, dass CRMP1 die Anordnung von Htt zu fibrillären, SDS-unlöslichen Aggregaten verringert. Durch Rasterkraftmikroskopie wurde der direkte Effekt von CRMP1 auf den Aggregationsprozess von Htt bestätigt. Ko-Immunopräzipitationsstudien zeigten, dass CRMP1 und Htt in Säugerzellen unter physiologischen Bedingungen miteinander interagieren. Es wurde nachgewiesen, dass CRMP1 die Polyglutamin-abhängige Aggregation und Toxizität von Htt in Zell- und Drosophila-Modellen von HD moduliert. Außerdem konnte CRMP1 in neuronalen Ablagerungen in R6/2 Mäusegehirnen und dessen selektive Spaltung durch Calpaine gezeigt werden. Diese Ergebnisse deuten darauf hin, dass die Lokalisation und Funktion von CRMP1 bei der Krankheitsentstehung verändert werden. / Huntington’s disease (HD) is a neurodegenerative disorder characterized by the accumulation of N-terminal polyglutamine (polyQ)-containing huntingtin (Htt) fragments in affected neurons. The mutant Htt (mHtt) protein is ubiquitously expressed but causes specific dysfunction and death of striatal medium-sized spiny neurons (MSNs) (Albin, 1995). It is assumed that striatum specific proteins interacting with Htt might play an important role in HD pathogenesis (Ross, 1995). Previous protein-protein interaction (PPI) studies demonstrated that many Htt-interacting proteins colocalize with insoluble Htt inclusions in HD brains and modulate the mHtt phenotype (Goehler 2004). A striatum-specific, dysregulated PPI network has been created recently by integrating PPI networks with information from gene expression profiling data (Chaurasia, unpublished data). One of the identified dysregulated proteins potentially involved in HD pathogenesis was the neuron-specific collapsin response-mediator protein 1 (CRMP1). Here, I show that CRMP1 reduces the self-assembly of SDS-insoluble mHtt protein aggregates in vitro, indicating a direct role of CRMP1 on the mHtt aggregation process. Coimmunoprecipitation studies showed that CRMP1 and Htt associate in mammalian cells under physiological conditions. In addition, CRMP1 localizes to abnormal neuronal inclusions and efficiently modulates polyQ-mediated Htt aggregation and toxicity in cell and Drosophila models of HD. This suggests that dysfunction of the protein is crucial for disease pathogenesis. Finally, I observed that CRMP1 localizes to neuronal inclusions and is selectively cleaved by calpains in R6/2 mouse brains, indicating that its distribution and function are altered in pathogenesis. In conclusion, this study presents new findings on the function of CRMP1 and its role in the pathogenesis of HD. The protein interacts with Htt and modulates its aggregation and toxicity, in this way influencing the molecular course of the disease.

Die Erkrankung Huntington s Chorea ist eine autosomal dominant vererbte Erkrankung, die gewöhnlich im mittleren Lebensabschnitt beginnt und unausweichlich zum Tode führt. In unserem Bestreben, Proteine zu identifizieren, welche an Prozessen "Upstream" oder "Downstream" des krankheitsverursachenden Proteins Huntingtin beteiligt sind, wurde das Proteom eines sehr gut etablierten Mausmodells mit Hilfe der Großgel 2D-Elektrophorese untersucht. Es konnte zum ersten Mal auf Proteinebene nachweisen werden, dass die Expression von zwei Serinproteasehemmern, alpha1-Antitrypsin und Contraspin und darüber hinaus eines Chaperons, alphaB-Kristallin, im Verlauf der Erkrankung abnimmt. Reduzierte Expression von alpha1-Antitrypsin und Contraspin konnte in Gehirn, Leber, Herz und Testes nahe dem Endstadium der Erkrankung nachgewiesen werden. Hier ist es wichtig festzustellen, dass die Expressionsabnahme von alpha1-Antitrypsin im Gehirn der Abnahme in der Leber im Herzen und in den Testes vorangeht. Eine verminderte Expression des Chaperons alphaB-Kristallin wurde nur im Gehirn gefunden. Für ein weiteres Protein, das Major Urinary Protein, wurde eine verminderte Expression in der Leber und im Urin von betroffenen Mäusen festgestellt. Damit konnte demonstriert werden, dass die Erkrankung auf Proteinebene auch ein Protein, das im Gehirn von transgenen Mäusen nicht vorkommt, beeinflusst. Bei Untersuchungen am Menschen wurde in drei Gehirnregionen von Postmortem-Gehirnen von Huntington s Chorea Patienten eine veränderte Expression von alpha1-Antitrypsin festgestellt. Wenn gewährleistet werden kann, dass die Konzentration von alpha1-Antitrypsin und alphaB-Kristallin während Huntington s Chorea im Gewebe nicht absinkt, könnte dies vielleicht neuronalen Zelltod verhindern und somit bei der Verzögerung des Krankheitsverlaufs nutzbringend eingesetzt werden. / Huntington disease is an autosomal dominantly inherited disease that usually starts in midlife and inevitably leads to death. In an effort to identify proteins involved in processes upstream or downstream of the disease causing huntingtin, the proteome of a well-established mouse model was studied by large-gel 2D electrophoresis. It could be demonstrated for the first time at the protein level that two serin protease inhibitors, alpha1-antitrypsin and contraspin and the chaperone alphaB-crystallin decrease in expression over the course of disease. Importantly, the alpha1-antitrypsin decrease in the brain precedes that in liver, heart and testes in mice. Reduced expression of alpha1-antitrypsin and contraspin could be detected in the brain, liver heart and testes close to terminal disease. Decreased expression of the chaperone alphaB-crystallin was found exclusively in the brain. Reduced expression of the liver specific major urinary proteins not found in the brain, was seen in affected mice, demonstrating that the disease exerts its influence on a protein not present in the brain of transgenic mice at the protein level. When investigating three human brain regions obtained post-mortem from Huntington s disease patients, alpha1-antitrypsin expression was also altered. Maintaining alpha1-antitrypsin and alphaB-crystallin availability during the course of Huntington s disease might prevent neuronal cell death and therefore could be useful in delaying the disease progression.