MR Imaging Signs of Gadolinium Retention Are Not Associated with Long-Term Motor and Cognitive Outcomes in Multiple Sclerosis.

BACKGROUND AND PURPOSE: The long-term impact of gadolinium retention in the dentate nuclei of patients undergoing administration of seriate gadolinium-based contrast agents is still widely unexplored. The aim of this study was to evaluate the impact of gadolinium retention on motor and cognitive disability in patients with MS during long-term follow-up. MATERIALS AND METHODS: In this retrospective study, clinical data were obtained from patients with MS followed in a single center from 2013 to 2022 at different time points. These included the Expanded Disability Status Scale score to evaluate motor impairment and the Brief International Cognitive Assessment for MS battery to investigate cognitive performances and their respective changes with time. The association with qualitative and quantitative MR imaging signs of gadolinium retention (namely, the presence of dentate nuclei T1-weighted hyperintensity and changes in longitudinal relaxation R1 maps, respectively) was probed using different General Linear Models and regression analyses. RESULTS: No significant differences in motor or cognitive symptoms emerged between patients showing dentate nuclei hyperintensity and those without visible changes on T1WIs (P = .14 and 0.92, respectively). When we tested possible relationships between quantitative dentate nuclei R1 values and both motor and cognitive symptoms, separately, the regression models including demographic, clinical, and MR imaging features explained 40.5% and 16.5% of the variance, respectively, without any significant effect of dentate nuclei R1 values (P = .21 and 0.30, respectively). CONCLUSIONS: Our findings suggest that gadolinium retention in the brains of patients with MS is not associated with long-term motor or cognitive outcomes.

Quantitative MRI in Multiple Sclerosis: From Theory to Application.

Quantitative MR imaging techniques allow evaluating different aspects of brain microstructure, providing meaningful information about the pathophysiology of damage in CNS disorders. In the study of patients with MS, quantitative MR imaging techniques represent an invaluable tool for studying changes in myelin and iron content occurring in the context of inflammatory and neurodegenerative processes. In the first section of this review, we summarize the physics behind quantitative MR imaging, here defined as relaxometry and quantitative susceptibility mapping, and describe the neurobiological correlates of quantitative MR imaging findings. In the second section, we focus on quantitative MR imaging application in MS, reporting the main findings in both the gray and white matter compartments, separately addressing macroscopically damaged and normal-appearing parenchyma.

A Combined Radiomics and Machine Learning Approach to Overcome the Clinicoradiologic Paradox in Multiple Sclerosis.

BACKGROUND AND PURPOSE: Conventional MR imaging explains only a fraction of the clinical outcome variance in multiple sclerosis. We aimed to evaluate machine learning models for disability prediction on the basis of radiomic, volumetric, and connectivity features derived from routine brain MR images. MATERIALS AND METHODS: In this retrospective cross-sectional study, 3T brain MR imaging studies of patients with multiple sclerosis, including 3D T1-weighted and T2-weighted FLAIR sequences, were selected from 2 institutions. T1-weighted images were processed to obtain volume, connectivity score (inferred from the T2 lesion location), and texture features for an atlas-based set of GM regions. The site 1 cohort was randomly split into training (n = 400) and test (n = 100) sets, while the site 2 cohort (n = 104) constituted the external test set. After feature selection of clinicodemographic and MR imaging-derived variables, different machine learning algorithms predicting disability as measured with the Expanded Disability Status Scale were trained and cross-validated on the training cohort and evaluated on the test sets. The effect of different algorithms on model performance was tested using the 1-way repeated-measures ANOVA. RESULTS: The selection procedure identified the 9 most informative variables, including age and secondary-progressive course and a subset of radiomic features extracted from the prefrontal cortex, subcortical GM, and cerebellum. The machine learning models predicted disability with high accuracy (r approaching 0.80) and excellent intra- and intersite generalizability (r ≥ 0.73). The machine learning algorithm had no relevant effect on the performance. CONCLUSIONS: The multidimensional analysis of brain MR images, including radiomic features and clinicodemographic data, is highly informative of the clinical status of patients with multiple sclerosis, representing a promising approach to bridge the gap between conventional imaging and disability.

Unraveling Deep Gray Matter Atrophy and Iron and Myelin Changes in Multiple Sclerosis.

BACKGROUND AND PURPOSE: Modifications of magnetic susceptibility have been consistently demonstrated in the subcortical gray matter of MS patients, but some uncertainties remain concerning the underlying neurobiological processes and their clinical relevance. We applied quantitative susceptibility mapping and longitudinal relaxation rate relaxometry to clarify the relative contribution of atrophy and iron and myelin changes to deep gray matter damage and disability in MS. MATERIALS AND METHODS: Quantitative susceptibility mapping and longitudinal relaxation rate maps were computed for 91 patients and 55 healthy controls from MR images acquired at 3T. Applying an external model, we estimated iron and myelin concentration maps for all subjects. Subsequently, changes of deep gray matter iron and myelin concentration (atrophy-dependent) and content (atrophy-independent) were investigated globally (bulk analysis) and regionally (voxel-based and atlas-based thalamic subnuclei analyses). The clinical impact of the observed MRI modifications was evaluated via regression models. RESULTS: We identified reduced thalamic (P < .001) and increased pallidal (P < .001) mean iron concentrations in patients with MS versus controls. Global myelin and iron content in the basal ganglia did not differ between the two groups, while actual iron depletion was present in the thalamus (P < .001). Regionally, patients showed increased iron concentration in the basal ganglia (P ≤ .001) and reduced iron and myelin content in thalamic posterior-medial regions (P ≤ .004), particularly in the pulvinar (P ≤ .001). Disability was predicted by thalamic volume (B = -0.341, P = .02), iron concentration (B = -0.379, P = .005) and content (B = -0.406, P = .009), as well as pulvinar iron (B = -0.415, P = .003) and myelin (B = -0.415, P = .02) content, independent of atrophy. CONCLUSIONS: Quantitative MRI suggests an atrophy-related iron increase within the basal ganglia of patients with MS, along with an atrophy-independent reduction of thalamic iron and myelin correlating with disability. Absolute depletions of thalamic iron and myelin may represent sensitive markers of subcortical GM damage, which add to the clinical impact of thalamic atrophy in MS.

Diffuse brain connectivity changes in Charcot-Marie-Tooth type 1a patients: a resting-state functional magnetic resonance imaging study.

BACKGROUND AND PURPOSE: Changes of brain structure and function have been described in peripheral neuropathies. The aim of our study was to systematically investigate possible modifications of major large-scale brain networks using resting-state functional magnetic resonance imaging (RS-fMRI) in Charcot-Marie-Tooth disease type 1A (CMT1A) patients. METHODS: In this cross-sectional study, 3-T MRI brain scans were acquired of right-handed genetically confirmed CMT1A patients and age- and sex-comparable healthy controls. Patients also underwent clinical and electrophysiological examinations assessing neurological impairment. RS-fMRI data were analysed using a seed-based approach, with 32 different seeds sampling the main hubs of default mode, sensorimotor, visual, salience (SN), dorsal attention, frontoparietal, language and cerebellar networks. Between-group differences in terms of functional connectivity (FC) with the explored seeds were tested voxelwise, correcting for local grey matter density to account for possible structural abnormalities, whilst the relationship between FC modifications and neurological impairment was investigated using robust correlation analyses. RESULTS: Eighteen CMT1A patients (34.0 ± 11.4 years; M/F 11/7) were enrolled, along with 20 healthy controls (30.1 ± 10.2 years; M/F 11/9). In the CMT group compared to controls, clusters of increased FC with the visual cortex (P = 0.001), SN (P < 6 × 10-4 ), dorsal attention network (P < 8 × 10-5 ) and language network (P < 7 × 10-4 ) were found, along with a single cluster of reduced FC with the visual cortex in the left lentiform nucleus (P = 10-6 ). A significant correlation emerged between neurophysiological impairment and increased FC with right temporal language areas (r = 0.655, P = 0.006), along with an association between walking ability and increased FC with the left supramarginal gyrus (SN) (r = 0.620, P = 0.006). CONCLUSIONS: Our data show evidence of diffuse functional reorganization involving multiple large-scale networks in the CMT1A brain, independent of structural modifications and partially correlating with peripheral nerve damage and functional impairment.

The complex phenotype of spinocerebellar ataxia type 48 in eight unrelated Italian families.

BACKGROUND AND PURPOSE: Heterozygous mutations in the STUB1 gene have recently been associated with an autosomal dominant form of spinocerebellar ataxia (SCA) associated with cerebellar cognitive-affective syndrome (CCAS), named SCA48. METHODS: Molecular screening was performed in a cohort of 235 unrelated patients with adult-onset, autosomal dominant (17) or sporadic (218) cerebellar ataxia, negative for pathological trinucleotide expansions in the common SCAs, FRDA and FXTAS loci, by using targeted multigene panels or whole-exome sequencing. Bioinformatics analyses, detailed neurological phenotyping and family segregation studies corroborated the pathogenicity of the novel STUB1 mutations. Clinico-diagnostic findings were reviewed to define the phenotypic spectrum. RESULTS: Eight heterozygous STUB1 mutations were identified, six of which were novel in 11 patients from eight index families, giving an estimated overall frequency of 3.4% (8/235) for SCA48 in our study cohort, rising to 23.5% (4/17) when considering only familial cases. All our SCA48 patients had cerebellar ataxia and dysarthria associated with cerebellar atrophy on brain magnetic resonance imaging; of note, many cases were also associated with parkinsonism, chorea and dystonia. CCAS also occurred frequently, whereas definite signs of pyramidal tract dysfunction and peripheral nervous system involvement were absent. One SCA48 patient presented with hypogonadism, associated with other autoimmune endocrine dysfunctions. CONCLUSIONS: Our results support SCA48 as a significant cause of adult-onset SCA. Besides CCAS, our SCA48 patients often showed movement disorders and other clinical manifestations previously described in SCAR16, linked to biallelic variants in the same gene, thus suggesting a continuous clinical spectrum and significant overlap amongst recessive and dominantly inherited mutations in STUB1.

Determinants of Deep Gray Matter Atrophy in Multiple Sclerosis: A Multimodal MRI Study.

BACKGROUND AND PURPOSE: Deep gray matter involvement is a consistent feature in multiple sclerosis. The aim of this study was to evaluate the relationship between different deep gray matter alterations and the development of subcortical atrophy, as well as to investigate the possible different substrates of volume loss between phenotypes. MATERIALS AND METHODS: Seventy-seven patients with MS (52 with relapsing-remitting and 25 with progressive MS) and 41 healthy controls were enrolled in this cross-sectional study. MR imaging investigation included volumetric, DTI, PWI and Quantitative Susceptibility Mapping analyses. Deep gray matter structures were automatically segmented to obtain volumes and mean values for each MR imaging metric in the thalamus, caudate, putamen, and globus pallidus. Between-group differences were probed by ANCOVA analyses, while the contribution of different MR imaging metrics to deep gray matter atrophy was investigated via hierarchic multiple linear regression models. RESULTS: Patients with MS showed a multifaceted involvement of the thalamus and basal ganglia, with significant atrophy of all deep gray matter structures (P < .001). In the relapsing-remitting MS group, WM lesion burden proved to be the main contributor to volume loss for all deep gray matter structures (P ≤ .006), with a minor role of local microstructural damage, which, in turn, was the main determinant of deep gray matter atrophy in patients with progressive MS (P ≤ .01), coupled with thalamic susceptibility changes (P = .05). CONCLUSIONS: Our study confirms the diffuse involvement of deep gray matter in MS, demonstrating a different behavior between MS phenotypes, with subcortical GM atrophy mainly determined by global WM lesion burden in patients with relapsing-remitting MS, while local microstructural damage and susceptibility changes mainly accounted for the development of deep gray matter volume loss in patients with progressive MS.

Redefining the Pulvinar Sign in Fabry Disease.

BACKGROUND AND PURPOSE: The pulvinar sign refers to exclusive T1WI hyperintensity of the lateral pulvinar. Long considered a common sign of Fabry disease, the pulvinar sign has been reported in many pathologic conditions. The exact incidence of the pulvinar sign has never been tested in representative cohorts of patients with Fabry disease. The aim of this study was to assess the prevalence of the pulvinar sign in Fabry disease by analyzing T1WI in a large Fabry disease cohort, determining whether relaxometry changes could be detected in this region independent of the pulvinar sign positivity. MATERIALS AND METHODS: We retrospectively analyzed brain MR imaging of 133 patients with Fabry disease recruited through specialized care clinics. A subgroup of 26 patients underwent a scan including 2 FLASH sequences for relaxometry that were compared with MRI scans of 34 healthy controls. RESULTS: The pulvinar sign was detected in 4 of 133 patients with Fabry disease (3.0%). These 4 subjects were all adult men (4 of 53, 7.5% of the entire male population) with renal failure and under enzyme replacement therapy. When we tested for discrepancies between Fabry disease and healthy controls in quantitative susceptibility mapping and relaxometry maps, no significant difference emerged for any of the tested variables. CONCLUSIONS: The pulvinar sign has a significantly lower incidence in Fabry disease than previously described. This finding, coupled with a lack of significant differences in quantitative MR imaging, allows hypothesizing that selective involvement of the pulvinar is a rare neuroradiologic sign of Fabry disease.

Identification of C12orf4 as a gene for autosomal recessive intellectual disability.

Intellectual disability (ID) is a major health problem in our society. Genetic causes of ID remain unknown because of its vast heterogeneity. Here we report two Finnish families and one Dutch family with affected individuals presenting with mild to moderate ID, neuropsychiatric symptoms and delayed speech development. By utilizing whole exome sequencing (WES), we identified a founder missense variant c.983T>C (p.Leu328Pro) in seven affected individuals from two Finnish consanguineous families and a deletion c.799_1034-429delinsTTATGA (p.Gln267fs) in one affected individual from a consanguineous Dutch family in the C12orf4 gene on chromosome 12. Both the variants co-segregated in the respective families as an autosomal recessive trait. Screening of the p.Leu328Pro variant showed enrichment in the North Eastern sub-isolate of Finland among anonymous local blood donors with a carrier frequency of 1:53, similar to other disease mutations with a founder effect in that region. To date, only one Arab family with a three affected individuals with a frameshift insertion variant in C12orf4 has been reported. In summary, we expand and establish the clinical and mutational spectrum of C12orf4 variants. Our findings implicate C12orf4 as a causative gene for autosomal recessive ID.

The influence of interoceptive awareness on functional connectivity in patients with irritable bowel syndrome.

Irritable bowel syndrome (IBS) is characterized by visceral hypersensitivity likely related to altered processing of sensory stimuli along the brain-gut axis. Previous neuroimaging studies demonstrated structural and functional alteration of several brain areas involved in bodily representation, e.g. the insula, in patients with IBS. By means of resting-state functional magnetic resonance imaging (rs-fMRI) we searched for alteration of functional connectivity within the network involved in self-bodily consciousness. We found significant inverse correlation between hypochondriasis assessed through a clinical questionnaire and connectivity between posterior cingulate cortex and left supramarginal gyrus, extending into the adjacent superior temporal gyrus. Moreover, we observed a significant and positive correlation between a clinical questionnaire assessing interoception and connectivity between left anterior ventral insula and two clusters located in supramarginal gyrus bilaterally.Our findings highlight an "abnormal network synchrony" reflecting functional alteration, in the absence of structural and micro-structural changes, which might represent a possible therapeutic target for Irritable Bowel Syndrome.

Upper motor neuron evaluation in multiple sclerosis patients treated with Sativex®.

BACKGROUND: Spasticity in multiple sclerosis (MS) results from an imbalance of inputs from descending pathways to the spinal motor circuits, as well as from a damage of the corticospinal tract (CST). OBJECTIVES: To assess CST impairment in MS patients with and without spasticity and to evaluate its evolution under Sativex® treatment. METHODS: Ten MS patients with spasticity ("cases") underwent clinical (EDSS, 9-hole Peg, Ashworth scale, Timed 25-Foot Walk, and NRS for spasticity), MRI (CST fractional anisotropy [FA]), and electrophysiological (central motor conduction time [CMCT] and H/M ratio) evaluations at baseline and after 12 months. We selected 20 MS patients without spasticity as control group at baseline. RESULTS: At baseline, cases showed a lower CST FA (0.492±0.045 vs 0.543±0.047; P=.01) and a higher CMCT (P=.001) compared to the control group. No correlations were found between clinical, electrophysiological, and MRI features. After 12 months, cases showed a decrease in non-prevalent degree of impairment (PDI) side FA (0.502±0.023 vs 0.516±0.033; P=.01) without differences for electrophysiological features compared to baseline. Treatment with Sativex® resulted in a reduction of NRS for spasticity (P=.01). CONCLUSIONS: We confirm the presence of CST impairment in MS patients with spasticity. We did not identify structural/electrophysiological correlates that could explain Sativex® clinical effect.

Grey:white matter ratio at diagnosis and the risk of 10-year multiple sclerosis progression.

BACKGROUND AND PURPOSE: Grey matter (GM) and white matter (WM) are both affected in multiple sclerosis (MS). WM is predominantly involved in inflammatory demyelination of relapsing-remitting MS (RRMS), whereas GM is predominantly involved in neurodegenerative processes of secondary progressive MS. Thus, we investigated the ratio between GM and WM volumes in predicting MS evolution. METHODS: The present 10-year retrospective cohort study included 149 patients with newly-diagnosed RRMS, undergoing magnetic resonance imaging for segmentation and brain volumetry. The ratio between GM and normal-appearing WM (NAWM) volumes was calculated for each subject. Outcome measures of interest were Expanded Disability Status Scale (EDSS) progression, reaching EDSS 4.0 and conversion to secondary progressive (SP) MS. RESULTS: During a period of 10.6 ± 2.4 years, a median 1.5 EDSS progression was observed (range 0-5.5), 54 subjects (36.2%) reached EDSS 4.0 and 30 subjects (20.1%) converted to SP. With ordinal logistic regression models, EDSS progression was associated with GM:NAWM ratio (coefficient, -2.918; 95% CI, -4.739-1.097). With Cox regression models, subjects with higher GM:NAWM ratio at diagnosis had a 90% lower rate of reaching EDSS 4.0 (hazard ratio, 0.111; 95% CI, 0.020-0.609) and of converting to secondary progressive MS (hazard ratio, 0.017; 95% CI, 0.001-0.203) compared with subjects with lower GM:NAWM ratio. CONCLUSIONS: The GM:NAWM ratio is a predictor of disability progression and of SP conversion in subjects with newly diagnosed RRMS, suggesting that GM and NAWM are variably affected in relation to disease evolution from the early phases of MS.

Sex differences in food choices, adherence to dietary recommendations and plasma lipid profile in type 2 diabetes - The TOSCA.IT study.

BACKGROUND AND AIMS: Diabetic women have a more adverse plasma lipid profile than men. Sex differences in dietary habits may play a role, but are little investigated. The study evaluates the quality of diet, adherence to the nutritional recommendations of the Diabetes and Nutrition Study Group and their relation with plasma lipid in men and women with diabetes. METHODS AND RESULTS: We studied 2573 people, aged 50-75, enrolled in the TOSCA.IT study (clinicaltrials.gov; NCT00700856). Plasma lipids were measured centrally. Diet was assessed with a semi-quantitative food frequency questionnaire. Women had a more adverse plasma lipid profile than men. Women consumed significantly more legumes, vegetables, fruits, eggs, milk, vegetable oils, and added sugar, whereas men consumed more starchy foods, soft drinks and alcoholic beverages. This stands for a higher proportion (%) of energy intake from saturated fat and added sugar (12.0 ± 2.4 vs 11.5 ± 2.5 and 3.4 ± 3.2 vs 2.3 ± 3.2, P < 0.04), and a higher intake of fiber (11.2 ± 2.8 vs 10.4 ± 2.6 g/1000 Kcal/day) in women. Adherence to the recommendations for saturated fat and fiber consumption was associated with significantly lower LDL-cholesterol regardless of sex. Adherence to the recommendations for added sugars was associated with significantly lower triglycerides and higher HDL-cholesterol in men and women. CONCLUSIONS: Men and women with diabetes show significant differences in adherence to nutritional recommendations, but sex differences in plasma lipid profile are unlikely to be explained by nutritional factors. Adherence to the nutritional recommendations is associated with a better plasma lipid profile regardless of sex, thus reinforcing the importance of substituting saturated for unsaturated fat sources, increasing fiber and reducing added sugar intake.

The combination of UCP3-55CT and PPARγ2Pro12Ala polymorphisms affects BMI and substrate oxidation in two diabetic populations.

BACKGROUND AND AIM: To evaluate the combined contribution of UCP3-55CT and PPARγ2 Pro12Ala polymorphisms as correlates of BMI, energy expenditure (REE) and substrate oxidation in people with type 2 diabetes. METHODS AND RESULTS: Two independent population with type 2 diabetes were studied: population A, n = 272; population B, n = 269. Based on both UCP3 and PPARγ2 genotypes three groups were created. Carriers of the PPARγ2 Pro12Ala in combination with the CC genotype of UCP3 (ProAla/CC, group 1); carriers of only one of these genotypes (either CC/ProPro or CT-TT/ProAla, group 2); people with neither variants (CT-TT/ProPro, group 3). In both populations BMI (kg/m(2)) was highest in group 1, intermediate in group 2 and lowest in group 3, independent of energy intake (i.e 35.3 ± 6.7 vs 33.4 ± 5.4 vs 31.8 ± 3, p < 0.02, population A; 32.4 ± 4.2 vs 31.7 ± 3.8 vs 30.1 ± 2.7; p < 0.03, population B). People with the ProAla/CC genotype (group 1) showed similar REE, but lower lipid oxidation (10.9 vs 13.9 g/kg fat free mass/day; p = 0.04) and higher carbohydrate oxidation (23.6 vs 15.6 g/kg fat free mass/day; p = 0.02) than carriers of other genotypes. CONCLUSIONS: The combination of UCP3-55 CC and PPARγ2 Pro12Ala genotypes is associated with significantly higher BMI than other PPARγ2-UCP3 genotype combinations, partly due to a reduced ability in lipids oxidation. The relative importance of these mechanism(s) may be different in non diabetic people.

A multiparametric and multiscale approach to automated segmentation of brain veins.

Cerebral vein analysis provides a fundamental tool to study brain diseases such as neurodegenerative disorders or traumatic brain injuries. In order to assess the vascular anatomy, manual segmentation approaches can be used but are observer-dependent and time-consuming. In the present work, a fully automated cerebral vein segmentation method is proposed, based on a multiscale and multiparametric approach. The combined investigation of the R2(*)- and a Vesselness probability-map was used to obtain a fast and highly reliable classification of venous voxels. A semiquantitative analysis showed that our approach outperformed the previous state-of-the-art algorithm both in sensitivity and specificity. Inclusion of this tool within a parametric brain framework may therefore pave the way for a quantitative study of the intracranial venous system.

Test meals rich in marine long-chain n-3 polyunsaturated fatty acids increase postprandial chylomicron response.

Postprandial lipid abnormalities are considered an independent cardiovascular risk factor. Hence, it is important to find nutritional strategies that are able to positively influence these abnormalities. Since the effect of n-3 polyunsaturated fatty acids (PUFA) and polyphenols on postprandial lipids in humans is still under debate, we evaluated the acute response of triglyceride-rich lipoproteins to test meals that are naturally rich in polyphenols and/or marine long-chain (LC) n-3 PUFAs. We hypothesized that LC n-3 PUFA would have a different effect on chylomicron and very low density lipoproteins when compared with polyphenols or their combination. We randomly assigned 78 individuals who were at high cardiometabolic risk to 4 isoenergetic diets. These diets only differed in amount of LC n-3 PUFA and/or polyphenols. Prior to starting the intervention, each subject underwent a test meal similar to the type of diet assigned: low in LC n-3 PUFA and polyphenols (control), rich in LC n-3 PUFA and low in polyphenols, rich in polyphenols and low in LC n-3 PUFA, or rich in both. Blood samples were taken before and up to 6 hours after the test meal in order to evaluate cholesterol and triglycerides (plasma and triglyceride-rich lipoprotein), apolipoprotein B-48 (large very low density lipoprotein), glucagon-like peptide-1, and free fatty acid plasma levels. The levels of chylomicron cholesterol and triglyceride in response to the test meal rich in LC n-3 PUFA were significantly higher than after the control meal (P = .037 and P = .018); there was no difference in the other variables. In conclusion, this study indicates that acute administration of marine LC n-3 PUFA increases postprandial chylomicron response in contrast with their lowering chronic effects. These differences underline the importance of understanding the acute and chronic effects of nutritional, as well as of other types of, interventions.

The energy intake modulates the association of the -55CT polymorphism of UCP3 with body weight in type 2 diabetic patients.

BACKGROUND: Previous association studies of the -55CT polymorphism of the uncoupling protein 3 (UCP3) gene with body mass index (BMI) have provided inconsistent results. The study aim is twofold: (1) to evaluate the association of the -55CT polymorphism of UCP3 with BMI in two independent populations to verify the reproducibility of the finding; (2) to evaluate whether this association is modulated by energy intake. METHODS: Study participants are 736 males and females with type 2 diabetes belonging to independent populations (N=394 population 1; N=342 population 2). Anthropometry and laboratory parameters were measured; in population 2, energy intake and physical exercise were also assessed. RESULTS: The -55CT polymorphism was associated with a significantly lower BMI in population 1 (27.8±3.9 vs 28.9±4.6 kg m(-2); P<0.02), the finding was confirmed in population 2 (that is, 30.3±6.0 vs 32.1±5.9 kg m(-2); P<0.01) independent of gender, age, HbA1c, use of drugs and energy intake. To evaluate the role of diet in population 2, the study participants were stratified by genotype and tertiles of energy intake. In both genotype groups, BMI increased with increasing caloric intake with a significant trend (P<0.001), the BMI difference between the two genotype groups was large and statistically significant in the lower tertile (27.6 vs 31.2 kg m(-2); P<0.001), intermediate in the second tertile and negligible in the upper tertile (32.8 vs 32.9; kg m(-2); nonsignificant). The multivariate regression analysis confirmed a significant interaction between genotype and energy intake as correlates of BMI independent of age, gender, glucose control, physical activity and medications for diabetes (P=0.004). CONCLUSIONS: The study replicates in two independent populations the association between the -55CT polymorphism of UCP3 and a lower BMI. This association was modulated by energy intake, thus suggesting that the unmeasured effect of diet may partly account for inconsistencies of prior association studies.

DNA methylation in intron 1 of the frataxin gene is related to GAA repeat length and age of onset in Friedreich ataxia patients.

BACKGROUND: The most frequent mutation of Friedreich ataxia (FRDA) is the abnormal expansion of a GAA repeat located within the first intron of FXN gene. It is known that the length of GAA is directly correlated with disease severity. The effect of mutation is a severe reduction of mRNA. Recently, a link among aberrant CpG methylation, chromatin organisation and GAA repeat was proposed. METHODS: In this study, using pyrosequencing technology, we have performed a quantitative analysis of the methylation status of five CpG sites located within the region upstream of GAA repeat, in 67 FRDA patients. RESULTS: We confirm previous observation about differences in the methylation degree between FRDA individuals and controls. We showed a direct correlation between CpG methylation and triplet expansion size. Significant differences were found for each CpG tested (ANOVA p<0.001). These differences were largest for CpG1 and CpG2: 84.45% and 76.80%, respectively, in FRDA patients compared to 19.65% and 23.34% in the controls. Most importantly, we found a strong inverse correlation between CpG2 methylation degree and age of onset (Spearman's rho = -0.550, p<0.001). CONCLUSION: Because epigenetic changes may cause or contribute to gene silencing, our data may have relevance for the therapeutic approach to FRDA. Since the analysis can be performed in peripheral blood leucocytes (PBL), evaluation of the methylation status of specific CpG sites in FRDA patients could be a convenient biomarker.