Polygenic risk in familial breast cancer: Changing the dynamics of communicating genetic risk.

Hereditary breast cancer is associated with known genetic changes: either variants that affect function in a few rare genes or an ever-increasing number of common genomic risk variants, which combine to produce a cumulative effect, known as a polygenic risk (PR) score. While the clinical validity and utility of PR scores are still being determined, the communication of PR is a new challenge for genetic health professionals. This study investigated how PR scores are discussed in the familial cancer clinic compared with a previous study assessing the communication of monogenic risk (MR) for breast cancer. Sixty-five PR consultations between genetic health professionals and women at familial risk of breast cancer were audiotaped, transcribed, and coded using a methodology adapted from the MR study. Analysis of consultations shows that while there were similarities in communicating MR and PR, the complexity and novelty of the polygenic information influenced the style of counseling used by genetic health professionals toward a teaching model of genetic counseling, rather than a patient-centered approach. In particular, compared to MR consultations, in PR consultations significantly fewer counselees (a) were asked about their reasons for attending genetic counseling; or (b) had their information preferences, decision-making style, medical knowledge, understanding, or concerns checked. In conclusion, it is anticipated that PR scores will become part of standard clinical practice. Thus, it will be important for all genetic health professionals to be appropriately educated so that they can tailor their communication to meet patient needs.

HD CAG-correlated gene expression changes support a simple dominant gain of function.

Huntington's disease is initiated by the expression of a CAG repeat-encoded polyglutamine region in full-length huntingtin, with dominant effects that vary continuously with CAG size. The mechanism could involve a simple gain of function or a more complex gain of function coupled to a loss of function (e.g. dominant negative-graded loss of function). To distinguish these alternatives, we compared genome-wide gene expression changes correlated with CAG size across an allelic series of heterozygous CAG knock-in mouse embryonic stem (ES) cell lines (Hdh(Q20/7), Hdh(Q50/7), Hdh(Q91/7), Hdh(Q111/7)), to genes differentially expressed between Hdh(ex4/5/ex4/5) huntingtin null and wild-type (Hdh(Q7/7)) parental ES cells. The set of 73 genes whose expression varied continuously with CAG length had minimal overlap with the 754-member huntingtin-null gene set but the two were not completely unconnected. Rather, the 172 CAG length-correlated pathways and 238 huntingtin-null significant pathways clustered into 13 shared categories at the network level. A closer examination of the energy metabolism and the lipid/sterol/lipoprotein metabolism categories revealed that CAG length-correlated genes and huntingtin-null-altered genes either were different members of the same pathways or were in unique, but interconnected pathways. Thus, varying the polyglutamine size in full-length huntingtin produced gene expression changes that were distinct from, but related to, the effects of lack of huntingtin. These findings support a simple gain-of-function mechanism acting through a property of the full-length huntingtin protein and point to CAG-correlative approaches to discover its effects. Moreover, for therapeutic strategies based on huntingtin suppression, our data highlight processes that may be more sensitive to the disease trigger than to decreased huntingtin levels.

Huntingtin facilitates polycomb repressive complex 2.

Huntington's disease (HD) is caused by expansion of the polymorphic polyglutamine segment in the huntingtin protein. Full-length huntingtin is thought to be a predominant HEAT repeat alpha-solenoid, implying a role as a facilitator of macromolecular complexes. Here we have investigated huntingtin's domain structure and potential intersection with epigenetic silencer polycomb repressive complex 2 (PRC2), suggested by shared embryonic deficiency phenotypes. Analysis of a set of full-length recombinant huntingtins, with different polyglutamine regions, demonstrated dramatic conformational flexibility, with an accessible hinge separating two large alpha-helical domains. Moreover, embryos lacking huntingtin exhibited impaired PRC2 regulation of Hox gene expression, trophoblast giant cell differentiation, paternal X chromosome inactivation and histone H3K27 tri-methylation, while full-length endogenous nuclear huntingtin in wild-type embryoid bodies (EBs) was associated with PRC2 subunits and was detected with trimethylated histone H3K27 at Hoxb9. Supporting a direct stimulatory role, full-length recombinant huntingtin significantly increased the histone H3K27 tri-methylase activity of reconstituted PRC2 in vitro, and structure-function analysis demonstrated that the polyglutamine region augmented full-length huntingtin PRC2 stimulation, both in Hdh(Q111) EBs and in vitro, with reconstituted PRC2. Knowledge of full-length huntingtin's alpha-helical organization and role as a facilitator of the multi-subunit PRC2 complex provides a novel starting point for studying PRC2 regulation, implicates this chromatin repressive complex in a neurodegenerative disorder and sets the stage for further study of huntingtin's molecular function and the impact of its modulatory polyglutamine region.

Communicating polygenic risk scores in the familial breast cancer clinic.

OBJECTIVE: To describe the communication of polygenic risk scores (PRS) in the familial breast cancer setting. METHODS: Consultations between genetic healthcare providers (GHP) and female patients who received their PRS for breast cancer risk were recorded (n = 65). GHPs included genetic counselors (n = 8) and medical practitioners (n = 5) (i.e. clinical geneticists and oncologists). A content analysis was conducted and logistic regression was used to assess differences in communication behaviors between genetic counselors (n = 8) and medical practitioners (n = 5). RESULTS: Of the 65 patients, 31 (47.7 %) had a personal history of breast cancer, 18 of whom received an increased PRS (relative risk >1.2). 25/34 unaffected patients received an increased PRS. Consultations were primarily clinician-driven and focused on biomedical information. There was little difference between the biomedical information provided by genetic counselors and medical practitioners. However, genetic counselors were significantly more likely to utilize strategies to build patient rapport and counseling techniques. CONCLUSIONS: Our findings provide one of the earliest reports on how breast cancer PRSs are communicated to women. PRACTICE IMPLICATIONS: Key messages for communicating PRSs were identified, namely: discussing differences between polygenic and monogenic testing, the multifactorial nature of breast cancer risk, polygenic inheritance and current limitation of PRSs.

Alzheimer's amyloid-ß and tau protein accumulation is associated with decreased expression of the LDL receptor-associated protein in human brain tissue.

INTRODUCTION: One of the major neuropathological features of Alzheimer's disease (AD) is the accumulation of amyloid-ß (Aß) protein in the brain. Evidence suggests that the low-density lipoprotein receptor-associated protein (RAP) binds strongly to Aß and enhances its cellular uptake and that decreased RAP expression correlates with increased Aß production in animal models of AD. METHODS: The current study examined whether RAP levels change in AD human brain tissue and whether they are related to the amount of AD pathology. RAP and NeuN levels were determined by Western blot, while low-density lipoprotein receptor-related protein 1 (LRP1), tau and Aß levels were determined by ELISA in the temporal cortex of 17 AD and 16 control cases. RESULTS: An increase in total Aß and insoluble and soluble tau protein was observed in AD brain tissue. In contrast, RAP levels were significantly decreased in AD brain tissue compared to controls. Correlation analysis revealed that levels of RAP correlated with both total Aß and soluble and insoluble tau levels. Neither LRP1 nor NeuN levels were significantly altered in AD brain tissue homogenates and did not correlate with Aß or tau protein levels. CONCLUSION: Reduction in RAP may contribute to the accumulation and aggregation of Aß in the AD brain.

Phosphorylation of soluble tau differs in Pick's disease and Alzheimer's disease brains.

Frontotemporal lobar degeneration (FTLD) is a common cause of presenile dementia characterised by behavioural and language disturbances. Pick's disease (PiD) is a subtype of FTLD, which presents with intraneuronal inclusions consisting of hyperphosphorylated tau protein aggregates. Although Alzheimer's disease (AD) is also characterised by tau lesions, these are both histologically and biochemically distinct from the tau aggregates found in PiD. What determines the distinct characteristics of these tau lesions is unknown. As phosphorylated, soluble tau has been suggested to be the precursor of tau aggregates, we compared both the level and phosphorylation profile of tau in tissue extracts of AD and PiD brains to determine whether the differences in the tau lesions are reflected by differences in soluble tau. Levels of soluble tau were decreased in AD but not PiD. In addition, soluble tau was phosphorylated to a greater extent in AD than in PiD and displayed a different phosphorylation profile in the two disorders. Consistently, tau kinases were activated to different degrees in AD compared with PiD. Such differences in solubility and phosphorylation may contribute, at least in part, to the formation of distinct tau deposits, but may also have implications for the clinical differences between AD and PiD.

No association of spastic paraparesis genes in PSEN1 Alzheimer's disease with spastic paraparesis.

Familial Alzheimer's disease due to presenilin 1 (PSEN1) mutations shows considerable phenotypic variability with differences in neuropathology and neurological symptoms. Spastic paraparesis is a common neurological phenotype associated with Alzheimer's disease arising from PSEN1 mutations. To investigate whether known genes that cause spastic paraparesis could act as Alzheimer's disease-modifier genes, we sequenced nine spastic paraparesis genes in three Alzheimer's disease families with PSEN1 exon 9 deletions. We did not observe any correlation of polymorphisms or mutations in the nine spastic paraparesis genes with the variable phenotype seen in families with Alzheimer's disease and spastic paraparesis. These results suggest a need for a continuing search for genes that cause the phenotypic variation in Alzheimer's disease and spastic paraparesis.

Intravesical rAd-IFNα/Syn3 for Patients With High-Grade, Bacillus Calmette-Guerin-Refractory or Relapsed Non-Muscle-Invasive Bladder Cancer: A Phase II Randomized Study.

Purpose Many patients with high-risk non-muscle-invasive bladder cancer (NMIBC) are either refractory to bacillus Calmette-Guerin (BCG) treatment or may experience disease relapse. We assessed the efficacy and safety of recombinant adenovirus interferon alfa with Syn3 (rAd-IFNα/Syn3), a replication-deficient recombinant adenovirus gene transfer vector, for patients with high-grade (HG) BCG-refractory or relapsed NMIBC. Methods In this open-label, multicenter (n = 13), parallel-arm, phase II study ( ClinicalTrials.gov identifier: NCT01687244), 43 patients with HG BCG-refractory or relapsed NMIBC received intravesical rAd-IFNα/Syn3 (randomly assigned 1:1 to 1 × 1011 viral particles (vp)/mL or 3 × 1011 vp/mL). Patients who responded at months 3, 6, and 9 were retreated at months 4, 7, and 10. The primary end point was 12-month HG recurrence-free survival (RFS). All patients who received at least one dose were included in efficacy and safety analyses. Results Forty patients received rAd-IFNα/Syn3 (1 × 1011 vp/mL, n = 21; 3 × 1011 vp/mL, n = 19) between November 5, 2012, and April 8, 2015. Fourteen patients (35.0%; 90% CI, 22.6% to 49.2%) remained free of HG recurrence 12 months after initial treatment. Comparable 12-month HG RFS was noted for both doses. Of these 14 patients, two experienced recurrence at 21 and 28 months, respectively, after treatment initiation, and one died as a result of an upper tract tumor at 17 months without a recurrence. rAd-IFNα/Syn3 was well tolerated; no grade four or five adverse events (AEs) occurred, and no patient discontinued treatment because of an adverse event. The most frequently reported drug-related AEs were micturition urgency (n = 16; 40%), dysuria (n = 16; 40%), fatigue (n = 13; 32.5%), pollakiuria (n = 11; 28%), and hematuria and nocturia (n = 10 each; 25%). Conclusion rAd-IFNα/Syn3 was well tolerated. It demonstrated promising efficacy for patients with HG NMIBC after BCG therapy who were unable or unwilling to undergo radical cystectomy.

Differences in regional brain atrophy in genetic forms of Alzheimer's disease.

Multiple degenerative hallmarks characterize Alzheimer's disease: insoluble protein deposition, neuronal loss and cortical atrophy. Atrophy begins in the medial temporal lobe and becomes global by end stage. In a small proportion of cases, these tissue changes are caused by mutations in three known genes. These cases are affected earlier in life and have more abundant protein deposition, which may indicate greater tissue atrophy and degeneration. This issue remains unresolved. Grey matter atrophy in different cortical regions was determined in genetic cases of Alzheimer's disease (N = 13) and compared to sporadic cases (N = 13) and non-diseased controls (N = 23). Genetic mutations were found to influence the degree and regional pattern of atrophy. The majority of cases had greater medial temporal atrophy than sporadic disease, suggesting that abnormalities affecting Abeta metabolism selectively increase hippocampal degeneration. Cases with mutations in presenilin-1 demonstrated additional increased frontotemporal atrophy. This effect may be due to the influence of presenilin-1 on tau phosphorylation and metabolism. These differences may explain the earlier onset ages in these different forms of Alzheimer's disease.

What is the dominant Abeta species in human brain tissue? A review.

Interest in the beta amyloid (Abeta) peptides continues to grow due to their known accumulation in the brains of patients with Alzheimer's disease and recent tantalising evidence that reducing such accumulations can reverse disease-associated functional deficits. Abeta peptides are naturally produced in every cell by proteolytic cleavage of the amyloid precursor protein with two main alloforms (40 or 42 amino acids) both of which are disease associated. The identification that genetic mutations causing Alzheimer's disease impact on Abeta production and clearance have allowed for the manipulation of these pathways in cellular and animal models. These studies show that the amount and type of Abeta in the brain has significant consequences on neural function. However, there have been significant difficulties in the conversion of these findings into successful treatments in humans. In this review we concentrate on data from human studies to determine any comparative differences in Abeta production and clearance that may assist with better treatment design and delivery. Abeta40 is the dominant peptide species in human cerebrospinal fluid accounting for approximately 90% of total Abeta under normal conditions. However, similar studies using disease free human brain tissue do not correlate with these findings. In these studies, concentrations of Abeta40 are low with Abeta42 often identified as the dominant species. The data suggest preferential brain tissue utilisation and/or clearance of Abeta40 compared with Abeta42, findings which may have been predicted by their physiochemical differences. In Alzheimer's disease this equilibrium is disrupted significantly increasing Abeta peptide levels in brain tissue. The disease-specific increase in Abeta40 brain tissue levels in Alzheimer's disease appears to be an important though overlooked pathological change compared with the well-documented Abeta42 change observed both in the aged and in Alzheimer's disease. These findings are discussed in association with Abeta peptide function and a model of toxicity developed.

Pick bodies in a family with presenilin-1 Alzheimer's disease.

Presenilin-1 (PS-1) mutations can cause Pick's disease without evidence of Alzheimer's disease (AD). We describe a family with a PS-1 M146L mutation and both Pick bodies and AD. Sarkosyl-insoluble hyperphosphorylated tau showed three bands consistent with AD, although dephosphorylation showed primarily three-repeat isoforms. M146L mutant PS-1 may predispose to both Pick's disease and AD by affecting multiple intracellular pathways involving tau phosphorylation and amyloid metabolism.

Positional effects of presenilin-1 mutations on tau phosphorylation in cortical plaques.

Mutations in presenilin-1 (PS-1) account for the majority of familial Alzheimer's disease (AD). While increasing Abeta42 is one mechanism whereby PS-1 mutations are thought to exert their pathogenic effect, little is known about the role of tau in PS-1 AD. This study compares staining (AT8 and tau-2), morphology and quantity of tau-immunoreactive cortical plaques in six PS-1 and five sporadic AD cases. The densities of tau-positive plaques differentiated PS-1 from sporadic AD cases. All PS-1 cases demonstrated a greater than 6-fold increase in tau-2-positive plaques. In PS-1 cases with mutations in exons 5 and 6, there was an increase in classical AD plaques containing hyperphosphorylated tau (AT8- and tau 2-positive). However, cases with exon 8 and 9 mutations had numerous cotton wool plaques containing nonhyperphosphorylated tau (tau-2-positive, AT8-negative). These findings suggest that PS-1 mutations increase tau deposition while mutation-specific cellular responses determine phosphorylation events and may influence cell death mechanisms.