Digenic inheritance of STUB1 variants and TBP polyglutamine expansions explains the incomplete penetrance of SCA17 and SCA48.

PURPOSE: This study aimed to unravel the genetic factors underlying missing heritability in spinocerebellar ataxia type 17 (SCA17) caused by polyglutamine-encoding CAG/CAA repeat expansions in the TBP gene. Alleles with >49 CAG/CAA repeats are fully penetrant. Most patients, however, carry intermediate TBP41-49 alleles that show incomplete penetrance. METHODS: Using next-generation sequencing approaches, we investigated 40 SCA17/TBP41-54 index patients, their affected (n = 55) and unaffected (n = 51) relatives, and a cohort of patients with ataxia (n = 292). RESULTS: All except 1 (30/31) of the index cases with TBP41-46 alleles carried a heterozygous pathogenic variant in the STUB1 gene associated with spinocerebellar ataxias SCAR16 (autosomal recessive) and SCA48 (autosomal dominant). No STUB1 variant was found in patients carrying TBP47-54 alleles. TBP41-46 expansions and STUB1 variants cosegregate in all affected family members, whereas the presence of either TBP41-46 expansions or STUB1 variants individually was never associated with the disease. CONCLUSION: Our data reveal an unexpected genetic interaction between STUB1 and TBP in the pathogenesis of SCA17 and raise questions on the existence of SCA48 as a monogenic disease with crucial implications for diagnosis and counseling. They provide a convincing explanation for the incomplete penetrance of intermediate TBP alleles and demonstrate a dual inheritance pattern for SCA17, which is a monogenic dominant disorder for TBP≥47 alleles and a digenic TBP/STUB1 disease (SCA17-DI) for intermediate expansions.

Missing the pathological expansion in Huntington disease: de novo c.51C>G variant on the expanded allele causing intrafamilial allele dropout.

Huntington disease (HD) is an autosomal dominant disease characterized by motor, behavioral, and cognitive symptoms, caused by the pathological expansion of more than 35 CAG/CAA repeats in the HTT gene. We describe the phenotype of a patient compatible with HD. Several family members were reported as affected, and a paternal cousin and his daughter carried 39 and 42 CAG/CAA. HD genetic testing in proband showed homozygosity for a 14 CAG/CAA allele. Considering the phenotype and family history, HTT gene sequence was performed, revealing heterozygosity for the c.51C>G variant that changes the last nucleotide before the CAG tract, causing misannealing of forward primer (HD344) and dropout of the expanded allele. Polymerase chain reaction (PCR) analysis performed with an alternative forward primer demonstrated a 41 CAG/CAA allele. The c.51C>G variant was not detected in the affected cousin, thus suggesting a de novo occurrence. The lack of biological samples from the proband father and grandmother prevented further investigations to establish in which family member the variant occurred. These data indicate that patients presenting HD phenotype, and homozygous for a normal HTT CAG/CAA allele should be thoroughly evaluated for the presence of a genetic variant, even de novo, within the repeat region that may hamper genetic diagnosis.

Frequency and distribution of polyQ disease intermediate-length repeat alleles in healthy Italian population.

BACKGROUND: Huntington disease (HD) and spinocerebellar ataxia type 1-2-17 (SCA1-2-17) are adult-onset autosomal dominant diseases, caused by triplet repeat expansions in the HTT, ATXN1, ATXN2, and TBP genes. Alleles with a repeat number just below the pathological threshold are associated with reduced penetrance and meiotic instability and are defined as intermediate alleles (IAs). OBJECTIVES: We aimed to determine the frequencies of IAs in healthy Italian subjects and to compare the proportion of the IAs with the prevalence of the respective diseases. METHODS: We analyzed the triplet repeat size in HTT, ATXN1, ATXN2, and TBP genes in the DNA samples from 729 consecutive adult healthy Italian subjects. RESULTS: IAs associated with reduced penetrance were found in ATXN2 gene (1 subject, 0.1%) and TBP gene (0.82%). IAs at risk for meiotic instability were found in HTT (5.3%) and ATXN2 genes (2.7%). In ATXN1, we found a low percentage of IAs (0.4%). Alleles lacking the common CAT interruption within the CAG sequence were also rare (0.3%). CONCLUSIONS: The high frequencies of IAs in HTT and ATXN2 genes suggest a correlation with the prevalence of the diseases in our population and support the hypothesis that IAs could represent a reservoir of new pathological expansions. On the opposite, ATXN1-IA were very rare in respect to the prevalence of SCA1 in our country, and TBP- IA were more frequent than expected, suggesting that other mechanisms could influence the occurrence of novel pathological expansions.

Multiple system atrophy and CAG repeat length: A genetic screening of polyglutamine disease genes in Italian patients.

Multiple system atrophy (MSA) is an adult onset, progressive, neurodegenerative disorder of unknown etiology characterized by autonomic dysfunction, parkinsonism (MSA-P) and cerebellar ataxia (MSA-C). The phenotypic spectrum may present overlapping features with other neurodegenerative diseases, particularly the autosomal dominant inherited polyglutamine disorders. To investigate the possible contribution of CAG expansions in the MSA phenotype, we analyzed the triplet repeat length in the autosomal dominant causative genes for spinocerebellar ataxia (SCA) type 1, 2, 3, 6, 7, 17, dentatorubral-pallidoluysian atrophy (DRPLA) and Huntington disease (HD) in a cohort of 246 Italian MSA patients. As comparison, 223 controls were also analyzed. The alleles were classified on the basis of CAG repeat length as "normal", "intermediate" or "expanded" according to literature. The MSA patients (101 men/145 women) had a mean age at onset of 58 years and a mean age at genetic testing of 63 years. MSA-C patients had significantly younger age at onset and at examination in comparison to MSA-P (p < 0.0001). We identified a SCA1 intermediate allele in a MSA-C subject (36 CAG), a SCA2 intermediate allele in a MSA-P patient (31 CAG), and a pathologically expanded SCA2 allele (36 CAG) in a patient initially misdiagnosed as MSA-C. No intermediate or expanded SCA alleles were detected in controls. The distribution of CAG repeat length was similar among groups except for SCA1 gene that showed a higher percentage of longer normal alleles in MSA-C as compared to MSA-P and controls (p < 0.0001). This study supports the utility of polyQ genetic testing in the differential diagnosis of MSA, and may suggest a possible role of SCA1 repeat length as risk factor for MSA-C. SCA1 and SCA2 genetic screening is recommended in MSA Italian patients.

Cortical thickness, stance control, and arithmetic skill: An exploratory study in premanifest Huntington disease.

BACKGROUND: Huntington disease (HD) is an inherited neurodegenerative disorder most commonly manifesting in adulthood. Identification of biomarkers tracking neurodegeneration before the onset of motor symptoms is important for future interventional studies. Our study aimed to contribute in the phenotypic characterization of the premanifest HD phase. METHODS: 28 premanifest subjects (preHD), 25 age-matched controls, and 12 manifest HD patients were enrolled for the study. The participants underwent a multimodal protocol including cognitive evaluations, arithmetic ability test, posturography, composite cerebellar functional test (CCFS), and brain 3T-MRI. PreHD were divided at the group median for predicted years to expected onset into "far-from-onset" (>15 years, PreHD-far), and "close-to-onset" (≤15 years, preHD-close). Basal ganglia volumes and cortical thickness were computed using FreeSurfer. RESULTS: PreHD-close showed significantly lower scores than controls in Symbol Digit Modalities Test (p = 0.017), Arithmetic subtraction task (p = 0.04), and MMSE (p < 0.006). At posturography, preHD-close showed increased sway velocity (<0.04) and distance (p < 0.02) compared to controls. PreHD-close had reduced striatum and globus pallidus volumes and left occipital cortical thinning compared to controls. Compared to PreHD far-from-onset, PreHD-close showed bilateral cortical thinning in occipital and parahippocampal regions, inversely correlating with burden score and prognostic index for HD. CCFS only differed between controls and manifest HD. PreHD far-from-onset did not show significant differences in comparison with controls. CONCLUSIONS: We confirmed that quantitative brain MRI represents a valid biomarker of neurodegeneration in preHD. Posturography and Arithmentic tests seem promising tools for detecting early changes in premanifest HD, but need to be further confirmed in large cohorts.

Characterization of chronic hepatitis B cases among foreign-born persons in six population-based surveillance sites, United States 2001-2010.

National surveys indicate prevalence of chronic hepatitis B among foreign-born persons in the USA is 5.6 times higher than US-born. Centers for Disease Control and Prevention funded chronic hepatitis B surveillance in Emerging Infections Program sites. A case was any chronic hepatitis B case reported to participating sites from 2001 to 2010. Sites collected standardized demographic data on all cases. We tested differences between foreign- and US-born cases by age, sex, and pregnancy using Chi square tests. We examined trends by birth country during 2005-2010. Of 36,008 cases, 21,355 (59.3%) reported birth in a country outside the USA, 2,323 (6.5%) were US-born. Compared with US-born, foreign-born persons were 9.2 times more frequent among chronic hepatitis B cases. Foreign-born were more frequently female, younger, ever pregnant, and born in China. Percentages of cases among foreign-born persons were constant during 2005-2010. Our findings support information from US surveillance for Hepatitis B screening and vaccination efforts.

Case-control study of hepatitis B and hepatitis C in older adults: Do healthcare exposures contribute to burden of new infections?

UNLABELLED: Reports of hepatitis B virus (HBV) and hepatitis C virus (HCV) transmission associated with unsafe medical practices have been increasing in the United States. However, the contribution of healthcare exposures to the burden of new infections is poorly understood outside of recognized outbreaks. We conducted a case-control study at three health departments that perform enhanced viral hepatitis surveillance in New York and Oregon. Reported cases of symptomatic acute hepatitis B and hepatitis C occurring in persons≥55 years of age from 2006 to 2008 were enrolled. Controls were identified using telephone directories and matched to individual cases by age group (55-59, 60-69, and ≥70 years) and residential postal code. Data collection covered exposures within 6 months before symptom onset (cases) or date of interview (controls). Forty-eight (37 hepatitis B and 11 hepatitis C) case and 159 control patients were enrolled. Case patients were more likely than controls to report one or more behavioral risk exposures, including sexual or household contact with an HBV or HCV patient, >1 sex partner, illicit drug use, or incarceration (21% of cases versus 4% of controls exposed; matched odds ratio [mOR]=7.1; 95% confidence interval [CI]: 2.1, 24.1). Case patients were more likely than controls to report hemodialysis (8% of cases; mOR=13.0; 95% CI: 1.5, 115), injections in a healthcare setting (58%; mOR=2.7; 95% CI: 1.3, 5.3), and surgery (33%; mOR=2.3; 95% CI: 1.1, 4.7). In a multivariate model, behavioral risks (adjusted OR [aOR]=5.4; 95% CI: 1.5, 19.0; 17% attributable risk), injections (aOR=2.7; 95% CI: 1.3, 5.8; 37% attributable risk), and hemodialysis (aOR=11.5; 95% CI: 1.2, 107; 8% attributable risk) were associated with case status. CONCLUSION: Healthcare exposures may represent an important source of new HBV and HCV infections among older adults.

Paediatric cardiac CT examinations: impact of the iterative reconstruction method ASIR on image quality--preliminary findings.

BACKGROUND: Radiation dose exposure is of particular concern in children due to the possible harmful effects of ionizing radiation. The adaptive statistical iterative reconstruction (ASIR) method is a promising new technique that reduces image noise and produces better overall image quality compared with routine-dose contrast-enhanced methods. OBJECTIVE: To assess the benefits of ASIR on the diagnostic image quality in paediatric cardiac CT examinations. MATERIALS AND METHODS: Four paediatric radiologists based at two major hospitals evaluated ten low-dose paediatric cardiac examinations (80 kVp, CTDI(vol) 4.8-7.9 mGy, DLP 37.1-178.9 mGy·cm). The average age of the cohort studied was 2.6 years (range 1 day to 7 years). Acquisitions were performed on a 64-MDCT scanner. All images were reconstructed at various ASIR percentages (0-100%). For each examination, radiologists scored 19 anatomical structures using the relative visual grading analysis method. To estimate the potential for dose reduction, acquisitions were also performed on a Catphan phantom and a paediatric phantom. RESULTS: The best image quality for all clinical images was obtained with 20% and 40% ASIR (p < 0.001) whereas with ASIR above 50%, image quality significantly decreased (p < 0.001). With 100% ASIR, a strong noise-free appearance of the structures reduced image conspicuity. A potential for dose reduction of about 36% is predicted for a 2- to 3-year-old child when using 40% ASIR rather than the standard filtered back-projection method. CONCLUSION: Reconstruction including 20% to 40% ASIR slightly improved the conspicuity of various paediatric cardiac structures in newborns and children with respect to conventional reconstruction (filtered back-projection) alone.

Pacemakers and magnetic resonance imaging: Current status and survey in Switzerland.

Electromagnetic fields arising from magnetic resonance imaging (MRI) can cause various clinically relevant functional disturbances in patients with cardiac pacemakers. Consequently, an implanted pacemaker is generally considered a contraindication for an MRI scan. With approximately 60 million MRI scans performed worldwide per year, MRI may be indicated for an estimated majority of pacemaker patients during the lifetime of their pacemakers. The availability of MR conditional pacemakers with CE labelling is of particular advantage since they allow the safe use of pacemakers in MRI. In this article the current state of knowledge on pacemakers and MR imaging is discussed. We present the results of a survey conducted among Swiss radiologists to assess current practice in patients with pacemakers.

Ultimate test bench for pediatric biventricular assist device based on artificial muscles.

Ventricular assist devices (VADs) are used in treatment for terminal heart failure or as a bridge to transplantation. We created biVAD using the artificial muscles (AMs) that supports both ventricles at the same time. We developed the test bench (TB) as the in vitro evaluating system to enable the measurement of performance. The biVAD exerts different pressure between left and right ventricle like the heart physiologically does. The heart model based on child's heart was constructed in silicone. This model was fitted with the biVAD. Two pipettes containing water with an ultrasonic sensor placed on top of each and attached to ventricles reproduced the preload and the after load of each ventricle by the real-time measurement of the fluid height variation proportionally to the exerted pressure. The LabVIEW software extrapolated the displaced volume and the pressure generated by each side of our biVAD. The development of a standardized protocol permitted the validation of the TB for in vitro evaluation, measurement of the performances of the AM biVAD herein, and reproducibility of data.

Multi-phase post-mortem CT angiography: development of a standardized protocol.

The objective of this work was to develop an easily applicable technique and a standardized protocol for high-quality post-mortem angiography. This protocol should (1) increase the radiological interpretation by decreasing artifacts due to the perfusion and by reaching a complete filling of the vascular system and (2) ease and standardize the execution of the examination. To this aim, 45 human corpses were investigated by post-mortem computed tomography (CT) angiography using different perfusion protocols, a modified heart-lung machine and a new contrast agent mixture, specifically developed for post-mortem investigations. The quality of the CT angiographies was evaluated radiologically by observing the filling of the vascular system and assessing the interpretability of the resulting images and by comparing radiological diagnoses to conventional autopsy conclusions. Post-mortem angiography yielded satisfactory results provided that the volumes of the injected contrast agent mixture were high enough to completely fill the vascular system. In order to avoid artifacts due to the post-mortem perfusion, a minimum of three angiographic phases and one native scan had to be performed. These findings were taken into account to develop a protocol for quality post-mortem CT angiography that minimizes the risk of radiological misinterpretation. The proposed protocol is easy applicable in a standardized way and yields high-quality radiologically interpretable visualization of the vascular system in post-mortem investigations.

The evolving epidemiology of hepatitis a in the United States: incidence and molecular epidemiology from population-based surveillance, 2005-2007.

BACKGROUND: The incidence of hepatitis A virus (HAV) disease is the lowest ever in the United States. We describe recent incidence and characteristics of cases of HAV disease from 6 US sites conducting hepatitis surveillance in the Emerging Infections Program. METHODS: Health departments conducted enhanced, population-based surveillance for HAV from 2005 through 2007. Demographic and risk factor data were collected on suspected cases (persons with a positive IgM anti-HAV result) using a standard form. Remnant serum specimens from a convenience sample of cases were tested by polymerase chain reaction, followed by sequencing the 315-nucleotide segment of the VP1-P2B junction. RESULTS: There were 1156 HAV cases reported during 2005 through 2007. The combined population under surveillance was 29.8 million in 2007. The overall annual incidence rate was 1.3 per 100 000 population (range by site, 0.7-2.3). Of reported cases, 53.4% were male, 42.4% were white, 44.7% were aged 15 to 39 years, and 91.4% resided in urban areas. Reported risk factors were international travel (45.8%), contact with a case (14.8%), employee or child in a daycare center (7.6%), exposure during a food or waterborne common-source outbreak (7.2%), illicit drug use (4.3%), and men who had sex with men (3.9%). Genotypes among the 271 case specimens were IA (87.8%), IB (11.4%), and IIIA (0.7%). Of the 271 polymerase chain reaction-positive specimens, 131 (48.3%) were from cases reporting travel or exposure to a traveler; 58 of the 131 cases reported travel to Mexico, and 53 of the 58 were within the US-IA(1) cluster. CONCLUSIONS: International travel was the predominant risk factor for HAV transmission. Health care providers should encourage vaccination of at-risk travelers.

Successful transapical aortic valve implantation in a congenital bicuspid aortic valve.

Transcatheter stent-valve implantation in stenosed congenital bicuspid aortic valves is under debate. Heavily calcified elliptic bicuspid valves represent a contraindication to catheter-based valve therapies because of a risk of stent-valve displacement, distortion, or malfunctioning after the implantation. In this case report we illustrate our experience with a patient suffering from stenosed congenital bicuspid aortic valve who successfully underwent a transapical 26-mm Edwards Sapien stent-valve (Edwards Lifesciences Inc, Irvine, CA) implantation. Postoperative distortion, malfunctioning, and paravalvular leaks were not detected.

Transapical aortic valve implantation without angiography: proof of concept.

BACKGROUND: Cardiac computed tomographic scans, coronary angiograms, and aortographies are routinely performed in transcatheter heart valve therapies. Consequently, all patients are exposed to multiple contrast injections with a following risk of nephrotoxicity and postoperative renal failure. The transapical aortic valve implantation without angiography can prevent contrast-related complications. METHODS: Between November 2008 and November 2009, 30 consecutive high-risk patients (16 female, 53.3%) underwent transapical aortic valve implantation without angiography. The landmarks identification, the stent-valve positioning, and the postoperative control were routinely performed under transesophageal echocardiogram and fluoroscopic visualization without contrast injections. RESULTS: Mean age was 80.1 +/- 8.7 years. Mean valve gradient, aortic orifice area, and ejection fraction were 60.3 +/- 20.9 mm Hg, 0.7 +/- 0.16 cm(2), and 0.526 +/- 0.128, respectively. Risk factors were pulmonary hypertension (60%), peripheral vascular disease (70%), chronic pulmonary disease (50%), previous cardiac surgery (13.3%), and chronic renal insufficiency (40%) (mean blood creatinine and urea levels: 96.8 +/- 54 microg/dL and 8.45 +/- 5.15 mmol/L). Average European System for Cardiac Operative Risk Evaluation was 32.2 +/- 13.3%. Valve deployment in the ideal landing zone was 96.7% successful and valve embolization occurred once. Thirty-day mortality was 10% (3 patients). Causes of death were the following: intraoperative ventricular rupture (conversion to sternotomy), right ventricular failure, and bilateral pneumonia. Stroke occurred in one patient at postoperative day 9. Renal failure (postoperative mean blood creatinine and urea levels: 91.1 +/- 66.8 microg/dL and 7.27 +/- 3.45 mmol/L), myocardial infarction, and atrioventricular block were not detected. CONCLUSIONS: Transapical aortic valve implantation without angiography requires a short learning curve and can be performed routinely by experienced teams. Our report confirms that this procedure is feasible and safe, and provides good results with low incidence of postoperative renal disorders.

Unexpected left ventricular free-wall rupture following an aortic catheter-valve implantation.

Our experience with the Sapien trans-apical aortic valve (Edwards Lifesciences Inc., Irvine, CA, USA) has been straightforward without per-procedural mortality except in 1/16 consecutive cases who developed non-apical haemorrhage early after valve implantation. We describe the case of an 84-year-old female carrying a very high operative risk (logistic EuroScore of 44%), who underwent a trans-apical stent-valve implantation for severe and symptomatic aortic valve stenosis (23 mm). Due to massive blood loss, an emergency sternotomy and cannulation for cardiopulmonary bypass resuscitation were necessary to treat (without success) an unusual and unexpected subaortic left ventricular free-wall rupture that occurred few minutes after the stent-valve positioning and implantation. To the best of our knowledge, this is the first described case of a left ventricular free-wall rupture occurring after an otherwise non-complicated standard catheter-based aortic valve replacement.

Variability of ascending aorta diameter measurements as assessed with electrocardiography-gated multidetector computerized tomography and computer assisted diagnosis software.

Recently, morphometric measurements of the ascending aorta have been done with ECG-gated multidector computerized tomography (MDCT) to help the development of future novel transcatheter therapies (TCT); nevertheless, the variability of such measurements remains unknown. Thirty patients referred for ECG-gated CT thoracic angiography were evaluated. Continuous reformations of the ascending aorta, perpendicular to the centerline, were obtained automatically with a commercially available computer aided diagnosis (CAD). Then measurements of the maximal diameter were done with the CAD and manually by two observers (separately). Measurements were repeated one month later. The Bland-Altman method, Spearman coefficients, and a Wilcoxon signed-rank test were used to evaluate the variability, the correlation, and the differences between observers. The interobserver variability for maximal diameter between the two observers was up to 1.2 mm with limits of agreement [-1.5, +0.9] mm; whereas the intraobserver limits were [-1.2, +1.0] mm for the first observer and [-0.8, +0.8] mm for the second observer. The intraobserver CAD variability was 0.8 mm. The correlation was good between observers and the CAD (0.980-0.986); however, significant differences do exist (P<0.001). The maximum variability observed was 1.2 mm and should be considered in reports of measurements of the ascending aorta. The CAD is as reproducible as an experienced reader.

Aortic remodelling in Fabry disease.

AIMS: To evaluate thoracic aortic dilation in patients with Fabry disease (FD). METHODS AND RESULTS: A cohort of 106 patients with FD (52 males; 54 females) from three European centres were studied. The diameter of the thoracic aorta was assessed at three levels (sinus of Valsalva, ascending aorta, and descending aorta) using echocardiograms and cardiovascular magnetic resonance imaging. Aortic dilation at the sinus of Valsalva was found in 32.7% of males and 5.6% of females; aneurysms were present in 9.6% of males and 1.9% of females. No aortic dilation was observed in the descending aorta. There was no correlation between aortic diameter at the sinus of Valsalva and cardiovascular risk factors. CONCLUSION: Fabry disease should be considered as a cardiovascular disease that affects the heart and arterial vasculature, including the thoracic aorta. Thus, patients with FD should be closely monitored for the presence, and possible progression and complications of aortic dilation. CLINICAL TRIAL REGISTRATION: Protocol 101/01. Ethics committee, Faculty of Medicine, Lausanne.