Association of mitochondrial DNA copy number with metabolic syndrome and type 2 diabetes in 14 176 individuals.

BACKGROUND: Mitochondria play an important role in cellular metabolism, and their dysfunction is postulated to be involved in metabolic disturbances. Mitochondrial DNA is present in multiple copies per cell. The quantification of mitochondrial DNA copy number (mtDNA-CN) might be used to assess mitochondrial dysfunction. OBJECTIVES: We aimed to investigate the cross-sectional association of mtDNA-CN with type 2 diabetes and the potential mediating role of metabolic syndrome. METHODS: We examined 4812 patients from the German Chronic Kidney Disease (GCKD) study and 9364 individuals from the Cooperative Health Research in South Tyrol (CHRIS) study. MtDNA-CN was measured in whole blood using a plasmid-normalized qPCR-based assay. RESULTS: In both studies, mtDNA-CN showed a significant correlation with most metabolic syndrome parameters: mtDNA-CN decreased with increasing number of metabolic syndrome components. Furthermore, individuals with low mtDNA-CN had significantly higher odds of metabolic syndrome (OR = 1.025; 95% CI = 1.011-1.039, P = 3.19 × 10-4 , for each decrease of 10 mtDNA copies) and type 2 diabetes (OR = 1.027; 95% CI = 1.012-1.041; P = 2.84 × 10-4 ) in a model adjusted for age, sex, smoking and kidney function in the meta-analysis of both studies. Mediation analysis revealed that the association of mtDNA-CN with type 2 diabetes was mainly mediated by waist circumference in the GCKD study (66%) and by several metabolic syndrome parameters, especially body mass index and triglycerides, in the CHRIS study (41%). CONCLUSIONS: Our data show an inverse association of mtDNA-CN with higher risk of metabolic syndrome and type 2 diabetes. A major part of the total effect of mtDNA-CN on type 2 diabetes is mediated by obesity parameters.

On the use of dense SNP marker data for the identification of distant relative pairs.

There has been recent interest in the exploitation of readily available dense genome scan marker data for the identification of relatives. However, there are conflicting findings on how informative these data are in practical situations and, in particular, sets of thinned markers are often used with no concrete justification for the chosen spacing. We explore the potential usefulness of dense single nucleotide polymorphism (SNP) arrays for this application with a focus on inferring distant relative pairs. We distinguish between relationship estimation, as defined by a pedigree connecting the two individuals of interest, and estimation of general relatedness as would be provided by a kinship coefficient or a coefficient of relatedness. Since our primary interest is in the former case, we adopt a pedigree likelihood approach. We consider the effect of additional SNPs and data on an additional typed relative, together with choice of that relative, on relationship inference. We also consider the effect of linkage disequilibrium. When overall relatedness, rather than the specific relationship, would suffice, we propose an approximate approach that is easy to implement and appears to compete well with a popular moment-based estimator and a recent maximum likelihood approach based on chromosomal sharing. We conclude that denser marker data are more informative for distant relatives. However, linkage disequilibrium cannot be ignored and will be the main limiting factor for applications to real data.

A K(ATP) channel gene effect on sleep duration: from genome-wide association studies to function in Drosophila.

Humans sleep approximately a third of their lifetime. The observation that individuals with either long or short sleep duration show associations with metabolic syndrome and psychiatric disorders suggests that the length of sleep is adaptive. Although sleep duration can be influenced by photoperiod (season) and phase of entrainment (chronotype), human familial sleep disorders indicate that there is a strong genetic modulation of sleep. Therefore, we conducted high-density genome-wide association studies for sleep duration in seven European populations (N=4251). We identified an intronic variant (rs11046205; P=3.99 × 10(-8)) in the ABCC9 gene that explains ≈5% of the variation in sleep duration. An influence of season and chronotype on sleep duration was solely observed in the replication sample (N=5949). Meta-analysis of the associations found in a subgroup of the replication sample, chosen for season of entry and chronotype, together with the discovery results showed genome-wide significance. RNA interference knockdown experiments of the conserved ABCC9 homologue in Drosophila neurons renders flies sleepless during the first 3 h of the night. ABCC9 encodes an ATP-sensitive potassium channel subunit (SUR2), serving as a sensor of intracellular energy metabolism.

Association between restless legs syndrome and hypertension: a preliminary population-based study in South Tyrol, Italy.

BACKGROUND AND PURPOSE: Restless legs syndrome (RLS) is a sleep-related movement disorder characterized by an irresistible urge to move the legs accompanied by paresthesia and/or dysesthesia that begins or worsens in the evening and night and that is partially or totally relieved by movement. Many studies have investigated the association between RLS and cardiovascular risk factors, particularly hypertension, leading to conflicting results. The aim of this study was to assess the association between RLS and hypertension considering also other cardiovascular risk factors that could act as confounders. METHODS: In all, 1709 participants of an on-going adult population-based study performed in South Tyrol, northern Italy, were enrolled. RLS was assessed through face-to-face interviews according to current International Restless Legs Syndrome Study Group diagnostic criteria. The presence of hypertension was self-reported and determined by questionnaires administered by trained study nurses. RESULTS: The association between RLS and hypertension was not significant after adjustment for age, sex, diabetes mellitus, history of myocardial infarction, raised blood lipids and body mass index (odds ratio 1.24, 95% CI 0.85-1.80, P = 0.271). CONCLUSION: Despite the small sample size of this study, RLS and hypertension were not associated in our adult population after adjustment for possible confounding factors. The presence of other cardiovascular risk factors could play a role as a confounder of this association.

Striatin knock out induces a gain of function of INa and impaired Ca2+ handling in mESC-derived cardiomyocytes.

AIM: Striatin (Strn) is a scaffold protein expressed in cardiomyocytes (CMs) and alteration of its expression are described in various cardiac diseases. However, the alteration underlying its pathogenicity have been poorly investigated. METHODS: We studied the role(s) of cardiac Strn gene (STRN) by comparing the functional properties of CMs, generated from Strn-KO and isogenic WT mouse embryonic stem cell lines. RESULTS: The spontaneous beating rate of Strn-KO CMs was faster than WT cells, and this correlated with a larger fast INa conductance and no changes in If. Paced (2-8 Hz) Strn-KO CMs showed prolonged action potential (AP) duration in comparison with WT CMs and this was not associated with changes in ICaL and IKr. Motion video tracking analysis highlighted an altered contraction in Strn-KO CMs; this was associated with a global increase in intracellular Ca2+, caused by an enhanced late Na+ current density (INaL) and a reduced Na+/Ca2+ exchanger (NCX) activity and expression. Immunofluorescence analysis confirmed the higher Na+ channel expression and a more dynamic microtubule network in Strn-KO CMs than in WT. Indeed, incubation of Strn-KO CMs with the microtubule stabilizer taxol, induced a rescue (downregulation) of INa conductance toward WT levels. CONCLUSION: Loss of STRN alters CMs electrical and contractile profiles and affects cell functionality by a disarrangement of Strn-related multi-protein complexes. This leads to impaired microtubules dynamics and Na+ channels trafficking to the plasma membrane, causing a global Na+ and Ca2+ enhancement.

Restless legs syndrome: an update on genetics and future perspectives.

Restless legs syndrome (RLS) is a common, underdiagnosed neurological condition with an age-dependent prevalence of up to 14%. Familial aggregation has been widely shown since Ekbom's first description of the disorder in 1945. Five loci (12q, 14q, 9p, 2q, and 20p) have been described so far, although no positive association with any specific genes, either within these loci or additional candidates investigated, has been reported. Two recent genome-wide association studies have reported positive association with sequence variants in or around specific genes on chromosomes 6p, 2p and 15q. The molecular findings, together with the variable expressivity of the phenotype, suggest a substantial clinical and genetic heterogeneity of RLS. This article reviews the clinical characteristics, diagnosis and epidemiology with a focus on the genetics and pathogenesis of RLS.

Adapted Finnish Migraine-Specific Questionnaire for family studies (FMSQ(FS)): a validation study in two languages.

BACKGROUND AND PURPOSE: The hypothesis of a genetic component in the etiology of migraine is getting a foothold. However, to explore genetic associations, precision in clinical phenotypization is crucial. For this reason, migraine-specific questionnaires, well discriminating between primary headaches, are required when large numbers of individuals need to be assessed. METHODS: We adapted and translated in two languages, German and Italian, the Finnish Migraine-Specific Questionnaire for use in family studies. RESULTS AND CONCLUSIONS: This adaptation proved to be reliable when differentiating from primary headaches, and to be in very good agreement with the standard for comparison. However, discriminating between migraine with and without aura still relays on a specialist evaluation. This article describes the validation of this questionnaire.

Isolation and marriage patterns in four South Tyrolean villages (Italy) during the nineteenth century.

No information is currently available on the marriage patterns of German-speaking communities of the South Tyrol area. The aim of this study is to investigate the reproductive isolation of four South Tyrolean mountain villages during the 19th century. Data about 3953 marriages were drawn from existing pedigrees and completed with data from the parish registers of the studied villages to calculate the following indicators: age at marriage, endogamy, inbreeding from dispensations and from isonymy and repeated pairs of surnames among couples. The results show high levels of endogamy (78-87%) and an elevated age at marriage in all the studied villages. The percentages of consanguineous marriages (10-33%) vary considerably but result overall in relatively low inbreeding values (alpha 0.0015-0.0036; Ft 0.0098-0.0138). Levels of endogamy are consistent with the geographic characteristics of the area, while inbreeding values are lower than those observed in previous studies on Alpine communities. This is due to a low frequency of marriages between close relatives, probably related to the peculiar demographic and cultural characteristics of the studied populations that differentiate them from neighbouring Italian-speaking villages.

Differential gene expression analysis of ovarian cancer in a population isolate.

Gene expression products represent candidate biomarkers with the potential for early screening and therapy of patients with ovarian serous carcinoma. The present study, using patients that originate from the population isolate of South Tyrol, Italy, substantiates the feasibility of differential gene expression analysis in a genetically isolated population for the identification of potential markers of ovarian cancer. Gene expression profiles of fresh-frozen ovarian serous papillary carcinoma samples were analyzed and compared to normal ovarian control tissues using oligonucleotide microarrays complementary to 14,500 human genes. Supervised analysis of gene expression profiling data identified 225 genes that are down-regulated and 635 that are up-regulated in malignant compared to normal ovarian tissues. Class-prediction analysis identified 40 differentially expressed genes for further investigation as potential classifiers for ovarian cancer, including 20 novel candidates. Our findings provide a glimpse into the potential of population isolate genomics in oncological research.

Substantia nigra hyperechogenicity correlates with clinical status and number of Parkin mutated alleles.

To further evaluate (1) transcranial sonography (TCS) for (pre)clinical diagnosis of Parkinson's disease (PD) and (2) to examine asymptomatic carriers of Parkin mutations we investigated substantia nigra (SN) hyperechogenicity in PD patients and unaffected subjects with and without Parkin mutations. The area (aSN) of the hyperechogenic SN were calculated bilaterally and study subjects were assigned to high versus low value groups. Eleven of the (affected and unaffected) mutation carriers had previously undergone 18-fluoro-dopa-(FDOPA)-PET scans. Fifty-eight individuals were investigated, including 24 with clinically definite and 34 without symptoms or signs of PD. Of the patients, three had one mutated and six had two mutated Parkin alleles. Of the unaffected subjects, 13 carried a single Parkin mutated allele. After dichotomization, 21 subjects had high and 37 subjects low values of mean aSN. Regarding the clinical status, 13 (62%) of the individuals with a high mean aSN had PD,while 26 (70%) of the study subjects with low values did not show signs of PD (p = 0.0393). Similarly, probands with high mean aSN values more frequently carried Parkin mutations (58%) than probands with low values (27%, p = 0.0234). A negative correlation between FDOPA uptake in the posterior putamen and maximum aSN was found in the group of mutation carriers (r = -0.809, p = 0.0234). In conclusion, hyperechogenicity of the SN is found in both idiopathic and Parkin-associated PD. Further strengthening the notion of a potential relationship between SN hyperechogenicity and Parkin mutational status, a larger aSN was associated with an increasing number of mutated alleles in our study.

32-channel time-correlated-single-photon-counting system for high-throughput lifetime imaging.

Time-Correlated Single Photon Counting (TCSPC) is a very efficient technique for measuring weak and fast optical signals, but it is mainly limited by the relatively "long" measurement time. Multichannel systems have been developed in recent years aiming to overcome this limitation by managing several detectors or TCSPC devices in parallel. Nevertheless, if we look at state-of-the-art systems, there is still a strong trade-off between the parallelism level and performance: the higher the number of channels, the poorer the performance. In 2013, we presented a complete and compact 32 × 1 TCSPC system, composed of an array of 32 single-photon avalanche diodes connected to 32 time-to-amplitude converters, which showed that it was possible to overcome the existing trade-off. In this paper, we present an evolution of the previous work that is conceived for high-throughput fluorescence lifetime imaging microscopy. This application can be addressed by the new system thanks to a centralized logic, fast data management and an interface to a microscope. The new conceived hardware structure is presented, as well as the firmware developed to manage the operation of the module. Finally, preliminary results, obtained from the practical application of the technology, are shown to validate the developed system.

Blink amplitude but not saccadic hypometria indicates carriers of Parkin mutations.

We investigated saccades, eyelid blinks, and their interaction in symptomatic (n = 22) and asymptomatic (n = 31) subjects with (n = 19) and without (n = 34) Parkin mutations. Saccadic hypometria was correlated with clinical symptoms of Parkinson's disease, irrespective of mutational status. By contrast, blink amplitude was increased in carriers of Parkin mutations independent of their clinical status. Saccade main sequence and blink effects on saccades were normal. We propose that increased blink amplitude may serve as an endophenotype in carriers of Parkin mutations.

Motor reorganization in asymptomatic carriers of a single mutant Parkin allele: a human model for presymptomatic parkinsonism.

Mutations in the Parkin gene are the most common known single cause of early-onset parkinsonism. It has been shown that asymptomatic carriers with a single mutant allele have latent presynaptic dopaminergic dysfunction in the striatum. Here we used functional MRI to map movement-related neuronal activity during internally selected or externally determined finger movements in 12 asymptomatic carriers of a Parkin mutation and 12 healthy non-carriers. Mean response times were 63 ms shorter during internally selected movements than during externally guided movements (P = 0.003). There were no differences in mean response times between groups (P > 0.2). Compared with externally determined movements, the internal selection of movements led to a stronger activation of rostral motor areas, including the rostral cingulate motor area (rCMA), rostral supplementary motor area, medial and dorsolateral prefrontal cortices. The genotype had a significant impact on movement-related activation patterns. Asymptomatic carriers showed a stronger increase in movement-related activity in the right rCMA and left dorsal premotor cortex, but only if movements relied on internal cues. In addition, synaptic activity in the rCMA had a stronger influence on activity in the basal ganglia in the context of internally selected movements in asymptomatic carriers relative to non-carriers. We infer that this reorganization of striatocortical motor loops reflects a compensatory effort to overcome latent nigrostriatal dysfunction.

Evaluation of 50 probands with early-onset Parkinson's disease for Parkin mutations.

BACKGROUND: Early onset PD has been associated with different mutations in the Parkin gene, including exon deletions and duplications. METHODS: The authors performed an extensive mutational analysis on 50 probands with onset of PD at younger than 50 years of age. Thirteen probands were ascertained from a registry of familial PD and 37 probands by age at onset at younger than 50 years, blind to family history. Mutational analysis was undertaken on the probands and available family members and included conventional techniques (single strand conformation polymorphism analysis and sequencing) and a newly developed method of quantitative duplex PCR to detect alterations of gene dosage (exon deletions and duplications) in PARKIN: RESULTS: Using this new technique, the authors detected eight alterations of gene dosage in the probands, whereas 12 mutations were found by conventional methods among the probands and another different mutation in an affected family member. In total, the authors identified compound heterozygous mutations in 14%, heterozygous mutations in 12%, and no Parkin mutation in 74% of the 50 probands. We expanded the occurrence of Parkin mutations to another ethnic group (African-American). CONCLUSION: The authors systematically screened all 12 Parkin exons by quantitative PCR and conventional methods in 50 probands. Eight mutations were newly reported, 2 of which are localized in exon 1, and 38% of the mutations were gene dosage alterations. These results underline the need to screen all exons and to undertake gene dosage studies. Furthermore, this study reveals a frequency of heterozygous mutation carriers that may signify a unique mode of inheritance and expression of the Parkin gene.

Novel three-stage ascertainment method: prevalence of PD and parkinsonism in South Tyrol, Italy.

BACKGROUND: A number of community-based studies on the prevalence of PD have been conducted worldwide, but they are often extremely costly and time consuming. OBJECTIVE: To assess the prevalence of PD and parkinsonism for the population aged between 60 and 85 years in South Tyrol, Northern Italy, using a novel population-based three-stage ascertainment method. METHODS: Seven hundred fifty persons aged 60 to 85 years from South Tyrol received a validated screening mail questionnaire for parkinsonism. In the second stage of the ascertainment method, trained primary care physicians (PCP) identified all persons with possible parkinsonism among those screened positive. In the third stage, movement disorders specialists excluded or confirmed the diagnosis in all identified people. RESULTS: The response rate was 87.6%. The prevalence rate per 100 population over 65 years of age was 1.5 (95% CI 0.6 to 2.3) for PD and 2.2 (95% CI 1.2 to 3.3) for parkinsonism after having been adjusted to the 1991 European standard population. Overall, 78% (95% CI 59 to 96%) of patients with parkinsonism were newly detected through the survey. CONCLUSIONS: The prevalence of PD and parkinsonism in people aged over 65 in South Tyrol was similar to that observed in door-to-door surveys in other European countries. The novel three-stage case ascertainment method employed proved a useful tool to substitute for expensive door-to-door surveys for prevalence studies of parkinsonism, detecting a high number of undiagnosed cases, particularly in geographically remote areas.

Parkin mutations in a patient with hemiparkinsonism-hemiatrophy: a clinical-genetic and PET study.

The authors describe a 37-year-old woman with early-onset hemiparkinsonism (HP) and ipsilateral body hemiatrophy (HA). Genetic analysis revealed a missense mutation (Arg275Trp) and a duplication of exon 7 of parkin. The complementary metabolic and receptor pattern of PET ligands corresponded to that typically found in idiopathic PD, although tracer binding asymmetry was lacking. Parkin mutations should be considered in HPHA, particularly when there is a younger age at onset and dystonia is an early sign.

Exon deletions in the GCHI gene in two of four Turkish families with dopa-responsive dystonia.

Most cases of dopa-responsive dystonia (DRD) are thought to be caused by mutations in the GCHI gene; however, by sequencing, mutations are found in only 40% to 60%. Recently, a single report identified, via Southern blot analysis, a large genomic GCHI deletion in a "mutation-negative" case. This report describes four families with DRD, two of which carry large deletions, thus confirming that deletions are an important subtype of GCHI mutations. These deletions were detected by quantitative duplex PCR that is amenable to DNA diagnostics.

Genome-wide scan for Parkinson's disease: the GenePD Study.

A genome-wide scan for idiopathic PD in a sample of 113 PD-affected sibling pairs is reported. Suggestive evidence for linkage was found for chromosomes 1 (214 cM, lod = 1.20), 9 (136 cM, lod = 1.30), 10 (88 cM, lod = 1.07), and 16 (114 cM, lod = 0.93). The chromosome 9 region overlaps the genes for dopamine beta-hydroxylase and torsion dystonia. Although no strong evidence for linkage was found for any locus, these results may be of value in comparison with similar studies by others.

Epidemiologic study of 203 sibling pairs with Parkinson's disease: the GenePD study.

OBJECTIVE: To examine patterns of familial aggregation and factors influencing onset age in a sample of siblings with PD. METHODS: Sibling pairs (n = 203) with PD were collected as part of the GenePD study. Standardized family history, medical history, and risk factor data were collected and analyzed. RESULTS: The mean age at onset was 61.4 years and did not differ according to sex, exposure to coffee, alcohol, or pesticides. Head trauma was associated with younger onset (p = 0.03) and multivitamin use with later onset (p = 0.007). Age at onset correlation between sibling pairs was significant (r = 0.56, p = 0.001) and was larger than the correlation in year of onset (r = 0.29). The mean difference in onset age between siblings was 8.7 years (range, 0 to 30 years). Female sex was associated with increased frequency of relatives with PD. The frequency of affected parents (7.0%) and siblings (5.1%) was increased when compared with frequency in spouses (2.0%). CONCLUSIONS: The greater similarity for age at onset than for year of onset in sibling pairs with PD, together with increased risk for biological relatives over spouses of cases, supports a genetic component for PD. Risk to siblings in this series is increased over that seen in random series of PD cases; however, patients in this sample have similar ages at onset and sex distribution as seen for PD generally. These analyses suggest that factors influencing penetrance are critical to the understanding of this disease.

Validation of a mail questionnaire for parkinsonism in two languages (German and Italian).

As part of a larger epidemiological study [Neuro-Epidemiology Project South-Tyrol (NEPT)], we investigated the accuracy of a mail questionnaire for parkinsonism in two languages (German and Italian). We administered the instrument to 40 randomly selected subjects with parkinsonism (Italian-speaking, n = 20; German-speaking, n = 20), attending our Parkinson's disease clinic regularly. Each patient was matched by age, sex and language with a subject without parkinsonism residing in the same South-Tyrol Province in Northern Italy. Subjects free of parkinsonism were recruited randomly from two group practices collaborating in the NEPT study. A questionnaire containing nine symptom questions and two additional questions about the patient's diagnosis of parkinsonism and/or treatment was mailed to each subject's home. Forty subjects with parkinsonism and 36 without parkinsonism participated in the study. All nine symptom items showed significant differences between affected and unaffected individuals. A combination of any three questions yielded the best balance between sensitivity (95%) and specificity (89%). There were no differences between the German- and Italian-speaking groups. We demonstrated the usefulness of a simple questionnaire for validating the diagnosis of parkinsonism irrespective of the primary native language.