Sex-related bias and exclusion mapping of the nonrecombinant portion of chromosome Y in human type 1 diabetes in the isolated founder population of Sardinia

Relevance of Essential Trace Elements in Nutrition and Drinking Water for Human Health and Autoimmune Disease Risk

Trace elements produce double-edged effects on the lives of animals and particularly of humans. On one hand, these elements represent potentially toxic agents; on the other hand, they are essentially needed to support growth and development and confer protection against disease. Certain trace elements and metals are particularly involved in humoral and cellular immune responses, playing the roles of cofactors for essential enzymes and antioxidant molecules. The amount taken up and the accumulation in human tissues decisively control whether the exerted effects are toxic or beneficial. For these reasons, there is an urgent need to re-consider, harmonize and update current legislative regulations regarding the concentrations of trace elements in food and in drinking water. This review aims to provide information on the interrelation of certain trace elements with risk of autoimmune disease, with a particular focus on type 1 diabetes and multiple sclerosis. In addition, an overview of the current regulations and regulatory gaps is provided in order to highlight the importance of this issue for everyday nutrition and human health.

ELMOD3-SH2D6 gene fusion as a possible co-star actor in autism spectrum disorder scenario

Autism spectrum disorder (ASD) is a group of neurodevelopmental disorders characterized by high heritability. It is known that genetic factors contribute to ASD pathogenesis. In particular, copy number variants (CNVs) are involved in ASD susceptibility and can affect gene expression regulation. 2p11.2 microdeletions encompassing ELMOD3, CAPG and SH2D6 genes have been described in four unrelated ASD families. The present study revealed that this microdeletion is responsible for the production of a chimeric transcript generated from the fusion between ELMOD3 and SH2D6. The identified transcript showed significantly higher expression levels in subjects carrying the deletion compared to control subjects, suggesting that it is not subjected to nonsense‐mediated decay and might encode for a chimeric protein. In conclusion, this study suggests the possible involvement of this gene fusion, together with the other previously identified variants, in ASD.

Analysis of a Sardinian Multiplex Family with Autism Spectrum Disorder Points to Post-Synaptic Density Gene Variants and Identifies CAPG as a Functionally Relevant Candidate Gene

Autism spectrum disorders (ASDs) are a group of neurodevelopmental disorders with high heritability, although their underlying genetic factors are still largely unknown. Here we present a comprehensive genetic characterization of two ASD siblings from Sardinia by genome-wide copy number variation analysis and whole exome sequencing (WES), to identify novel genetic alterations associated with this disorder. Single nucleotide polymorphism (SNP) array data revealed a rare microdeletion involving CAPG, ELMOD3, and SH2D6 genes, in both siblings. CAPG encodes for a postsynaptic density (PSD) protein known to regulate spine morphogenesis and synaptic formation. The reduced CAPG mRNA and protein expression levels in ASD patients, in the presence of hemizygosity or a particular genetic and/or epigenetic background, highlighted the functional relevance of CAPG as a candidate gene for ASD. WES analysis led to the identification in both affected siblings of a rare frameshift mutation in VDAC3, a gene intolerant to loss of function mutation, encoding for a voltage-dependent anion channel localized on PSD. Moreover, four missense damaging variants were identified in genes intolerant to loss of function variation encoding for PSD proteins: PLXNA2, KCTD16, ARHGAP21, and SLC4A1. This study identifies CAPG and VDAC3 as candidate genes and provides additional support for genes encoding PSD proteins in ASD susceptibility.

Zinc Status and Autoimmunity: A Systematic Review and Meta-Analysis

Zinc is an essential trace element for living organisms and their biological processes. Zinc plays a key role in more than 300 enzymes and it is involved in cell communication, proliferation, differentiation and survival. Zinc plays also a role in regulating the immune system with implications in pathologies where zinc deficiency and inflammation are observed. In order to examine the experimental evidence reported in the literature regarding zinc levels in the body of patients with autoimmune disorders compared to control individuals, a systematic review and meta-analysis were performed. From 26,095 articles identified by literature search, only 179 of them were considered potentially relevant for our study and then examined. Of the 179 articles, only 62 satisfied the inclusion criteria. Particularly for Fixed Model, Zn concentration in both serum (mean effect = −1.19; confidence interval: −1.26 to −1.11) and plasma (mean effect = −3.97; confidence interval: −4.08 to −3.87) samples of autoimmune disease patients was significantly lower than in controls. The data presented in our work, although very heterogeneous in the manner of collecting and investigating samples, have proved to be extremely consistent in witnessing a deficiency of zinc in serum and plasma of patients compared to controls.

Type 1 diabetes in Sardinia: facts and hypotheses in the context of worldwide epidemiological data

Type 1 diabetes (T1D) results from an autoimmune destruction of insulin-producing beta cells that requires lifelong insulin treatment. While significant advances have been achieved in treatment, prevention of complications and quality of life in diabetic people, the identification of environmental triggers of the disease is far more complex. The island of Sardinia has the second highest incidence of T1D in the world (45/100,000), right after Finland (64.2/100,000). The genetic background as well as the environment of the island's inhabitants makes it an ideal region for investigating environmental, immunological and genetic factors related to the etiopathogenesis of T1D. Several epidemiological studies, conducted over the years, have shown that exposures to important known environmental risk factors have changed over time, including nutritional factors, pollution, chemicals, toxins and infectious diseases in early life. These environmental risk factors might be involved in T1D pathogenesis, as they might initiate autoimmunity or accelerate and precipitate an already ongoing beta cell destruction. In terms of environmental factors, Sardinia is also particular in terms of the incidence of infection with Mycobacterium avium paratuberculosis (MAP) that recent studies have linked to T1D in the Sardinian population. Furthermore, the unique geochemical profile of Sardinia, with its particular density of heavy metals, leads to the assumption that exposure of the Sardinian population to heavy metals could also affect T1D incidence. These factors lead us to hypothesize that T1D incidence in Sardinia may be affected by the exposure to multifactorial agents, such as MAP, common viruses and heavy metals.

Association of lymphotoxin alpha polymorphism with type 1 diabetes in a Tunisian population

We investigated the association of the lymphotoxin (LT)-α gene polymorphism +249A/G with type 1 diabetes. The distribution of genotypes of the LT-α +249A/G single nucleotide polymorphism (SNP) was assessed in 115 diabetic patients and 123 normoglycemic control subjects, using PCR-restriction fragment length polymorphism analysis. Among unselected patients, the SNP was significantly associated with increased risk of diabetes (χ2 = 8.44, p = 0.014) and was found to be more pronounced among female (χ2 = 8.37, p = 0.02) than male (χ2 = 6.11, p = 0.047) patients. A significant association was detected between LT-α +249A/G and increased risk of diabetes, in particular for young-onset patients (χ2 = 6.92, p = 0.031). Moreover, we reported significant differences in levels of HbA1c, triglycerides, alanine transaminase, and anti-glutamic acid decarboxylase-65 among alleles. Additional studies with extended patient age groups and different ethnicities are needed to confirm our findings.

More than 20 years of registration of type 1 diabetes in Sardinian children: temporal variations of incidence with age, period of diagnosis, and year of birth

We analyzed Sardinian registry data to assess time trends in incidence rates (IRs) of type 1 diabetes during the period 1989-2009 (2,371 case subjects 0-14 years of age). Poisson regression models were used to estimate the effects of sex, age, period of diagnosis, and birth cohorts. IR was 44.8 cases/100,000 person-years (95% CI 43.1-46.7). The annual increase was 2.12% (1.45-2.80; test for linear trend, P < 0.001). For boys, the increasing trend was evident up to 5 years of age and for girls up to 8 years of age. Compared with the 1989-1994 birth cohort, the relative risk increased from 0.78 (0.61-1.10) in 1974-1979 to 1.62 (1.18-2.23) in 2004-2009. The increase over period was less striking, with a tendency to regress in more recent years. The best-fitting model for boys included age and a linear time trend, and for girls age and nonlinear effects of calendar period and birth cohort. In conclusion, incidence increased over time, and the increase tended to level off in more recent years by calendar period but not by birth cohort, with some evidence of a stronger increase among girls than boys. Should the increase be attributable to the effects of some perinatal environmental factor, this would mean that such a factor has started affecting females before males.

Low-pass DNA sequencing of 1200 Sardinians reconstructs European Y-chromosome phylogeny

Genetic variation within the male-specific portion of the Y chromosome (MSY) can clarify the origins of contemporary populations, but previous studies were hampered by partial genetic information. Population sequencing of 1204 Sardinian males identified 11,763 MSY single-nucleotide polymorphisms, 6751 of which have not previously been observed. We constructed a MSY phylogenetic tree containing all main haplogroups found in Europe, along with many Sardinian-specific lineage clusters within each haplogroup. The tree was calibrated with archaeological data from the initial expansion of the Sardinian population ~7700 years ago. The ages of nodes highlight different genetic strata in Sardinia and reveal the presumptive timing of coalescence with other human populations. We calculate a putative age for coalescence of ~180,000 to 200,000 years ago, which is consistent with previous mitochondrial DNA-based estimates.

The incidence of type 1 diabetes mellitus among 15-34 years aged Lithuanian population: 18-year incidence study based on prospective databases

Background

The aim of this prospective study was to determine the incidence of type 1 diabetes mellitus in 15-34-year-aged Lithuanian males and females during 1991 - 2008

Methods

A contact system with general practitioners covering 100% of the 15-34-year-aged Lithuanian population was the primary data source. Reports from regional endocrinologists and statistical note-marks of State patient insurance fund served as secondary sources for case ascertainment.

Results

The average age-standardized incidence rate was 8.30 per 100,000 persons per year (95% Poisson distribution confidence interval [CI] 7.90-8.71) during 1991 - 2008 and was statistically significantly higher among males (10.44 per 100,000 persons per year, 95% CI 9.82-11.10) in comparison with females (6.10 per 100,000, 95% CI 5.62-6.62). Male/female rate ratio was 1.71 (95% CI 1.63-1.80). Results of the linear 1991 - 2008 regression model showed that the incidence of Type 1 diabetes in 15-34-year-aged males and females decreased slightly over the time (r = -0.215, p > 0.05).

Conclusions

Our data demonstrated the male predominance in primary incidence of type 1 diabetes mellitus in 15-34-year-aged population in Lithuania. The incidence of type 1 diabetes mellitus in 15-34-year-aged males and females decreased slightly during 1991-2008.

Characterization of thyroglobulin epitopes in Sardinian adults and juveniles with Hashimoto's thyroiditis: evidence against a major effect of age and genetic background on B-cell epitopes

BACKGROUND

Using recombinant human monoclonal thyroglobulin antibodies expressed as Fab molecules (TgAb-Fab), we have recently confirmed the restriction of Tg epitopes in Hashimoto's thyroiditis (HT).

OBJECTIVE

To investigate Tg epitopes of serum TgAb in HT adults and HT juveniles from a geographically isolated area (Sardinia).

DESIGN AND PATIENTS

Serum TgAb of 39 Sardinian HT adults, 53 Sardinian HT juveniles and 45 non-Sardinian HT adults were evaluated. The binding of serum TgAb to Tg in ELISA was inhibited by four recombinant human TgAb-Fab, identifying Tg epitopic regions A-D. The percentage of Tg binding inhibition was calculated comparing the binding of serum TgAb in presence of each TgAb-Fab with that in its absence.

RESULTS

In the whole cohort of 137 patients, A region TgAb-Fab induced the highest levels of inhibition (55.3 +/- 17.8%) (mean +/- SD). Lower levels of inhibition were induced by TgAb-Fab of regions B (27.8 +/- 25.8%), C (26.8 +/- 24.6%) and D (17.5 +/- 18.4%). In Sardinian HT adults inhibition by TgAb-Fab of regions A, B and C were comparable to Sardinian HT juveniles; the marginal D region TgAb-Fab induced a slightly higher inhibition (22.1 vs. 13.8%; P = 0.034) in the former than in the latter group. In Sardinian and non-Sardinian HT adults inhibitions by the four TgAb-Fab were similar.

CONCLUSIONS

In HT, the Tg epitope pattern of serum TgAb was similar in juveniles and adults from a geographically restricted area and in two adult populations from different geographical areas. Thus, in HT, neither age nor genetic background appear to influence B-cell epitopes.

Very high and increasing incidence of type 1 diabetes mellitus in Newfoundland and Labrador, Canada

OBJECTIVE

To determine the incidence of type 1 diabetes mellitus (T1DM) among children aged 0-14 yr inclusive in the Canadian province of Newfoundland and Labrador (NL).

METHODS

Prospective and retrospective cohort study of the incidence of T1DM in children aged 0-14 yr from 1987 to 2005. Identified cases during this time period were ascertained from several sources and verified using the capture-recapture technique.

RESULTS

Over the study period, 732 children aged 0-14 yr were diagnosed with T1DM. The incidence of T1DM in this population over the period 1987-2005 inclusive was 35.08 per 100,000 (95% confidence interval: 32.54, 37.62). The incidence over this period increased linearly at the rate of 0.78 per 100 000 per year. There was a significant difference between the incidence of 31.61 per 100,000 for boys in the 0-4-yr age-group and 19.05 per 100,000 for girls in the 0-4-yr age-group (p = 0.001). The incidence was very high throughout the entire province.

CONCLUSIONS/INTERPRETATION

The province of NL has one of the highest incidences of T1DM reported worldwide. The incidence is increasing over the 19-yr study period.

HLA-DQ and susceptibility to celiac disease: evidence for gender differences and parent-of-origin effects

BACKGROUND AND AIMS

Celiac disease (CD) is twice as frequent among female than male. Despite the large number of reports on the DQ2/DQ8 association, no systematic studies have investigated a possible different role of the HLA genes in the two genders. We performed case-control and family-based analyses of DR-DQ variants in a pediatric CD cohort with the aim of comparing female to male associations and to investigate the paternal/maternal inheritance of the disease-predisposing haplotypes.

METHODS

A total of 281 female and 156 male pediatric celiac patients, 292 nuclear families, and 551 controls were genotyped for HLA-DRB1, DQA1, and DQB1 loci. Odds ratio, parental origin of the disease-associated haplotypes, and transmission ratio distortion were evaluated in-between male and female cases.

RESULTS

DQ2/DQ8 were more frequent in female than in male patients (94% F, 85% M; P = 1.6 x 10(-3)) with a 99.1% and 90.5% calculated negative predictive value of the HLA test, respectively. Surprisingly, the majority of the 39 DQ2/DQ8 negative cases were male. The analysis of the DQ2 haplotype origin showed that 61% of female patients and 42% of male patients carried a paternal combination (P = 0.02). The transmission disequilibrium test (TDT) proved the major distortion in the DR3-DQ2 transmission from fathers to daughters.

CONCLUSIONS

CD is confirmed to be more prevalent in female than in male (F:M = 1.8) but, in DQ2/DQ8 negative patients, we found an unexpected male excess (F:M = 0.7). Moreover, only the inheritance of a paternal DQ2 haplotype led to a daughters predominance. These data show a role of HLA genes on the disease sex bias and suggest a possible different effect of parent-specific epigenetic modifications in the two genders.

Y-chromosome based evidence for pre-neolithic origin of the genetically homogeneous but diverse Sardinian population: inference for association scans

The island of Sardinia shows a unique high incidence of several autoimmune diseases with multifactorial inheritance, particularly type 1 diabetes and multiple sclerosis. The prior knowledge of the genetic structure of this population is fundamental to establish the optimal design for association studies in these diseases. Previous work suggested that the Sardinians are a relatively homogenous population, but some reports were contradictory and data were largely based on variants subject to selection. For an unbiased assessment of genetic structure, we studied a combination of neutral Y-chromosome variants, 21 biallelic and 8 short tandem repeats (STRs) in 930 Sardinian males. We found a high degree of interindividual variation but a homogenous distribution of the detected variability in samples from three separate regions of the island. One haplogroup, I-M26, is rare or absent outside Sardinia and is very common (0.37 frequency) throughout the island, consistent with a founder effect. A Bayesian full likelihood analysis (BATWING) indicated that the time from the most recent common ancestor (TMRCA) of I-M26, was 21.0 (16.0–25.5) thousand years ago (KYA) and that the population began to expand 14.0 (7.8–22.0) KYA. These results suggest a largely pre-Neolithic settlement of the island with little subsequent gene flow from outside populations. Consequently, Sardinia is an especially attractive venue for case-control genome wide association scans in common multifactorial diseases. Concomitantly, the high degree of interindividual variation in the current population facilitates fine mapping efforts to pinpoint the aetiologic polymorphisms.

No influence of chromosome Y haplogroup variation in acute graft-versus-host disease in sardinia

The donor-recipient sex-related mismatch has been reported as a risk factor for acute graft-versus-host disease (GVHD). However, the results obtained in previous studies appear to be contradictory. Here we evaluate the impact of donor-recipient sex-related mismatch in a series of 204 Sardinian individuals (92.1% of them affected by Beta- Thalassemia major) who underwent bone marrow transplantation (BMT) from human leukocyte antigen (HLA) identical siblings. In all, 78 of these patients had acute GVHD (aGVHD). We found that also in this homogenous group of patients from a homogenous population, the donor-female/recipient-male pair provided an increased risk for aGVHD when compared with a reference donor-male/recipient-male pair (POR=2.3, P=0.042). This data could be consistent with a role of variation in the male-specific portion of the Y chromosome in aGVHD. To assess this, we compared the distribution of the main Y-chromosome haplogroups in 28 male patients, who had aGVHD and underwent BMT from HLA-identical sisters, and 366 ethnically-matched controls. No significant differences were observed. These findings do not support the presence of Y chromosome founder variants contributing significantly to aGVHD in the Sardinian population.

RET proto-oncogene in Sardinia: V804M is the most frequent mutation and may be associated with FMTC/MEN-2A phenotype

OBJECTIVE

Genetic screening of RET proto-oncogene is a powerful tool for the early identification of familial cases of medullary thyroid carcinoma (MTC), comprising isolated familial thyroid medullary carcinoma (FMTC) and multiple endocrine neoplasia syndromes 2A (MEN-2A) and 2B (MEN-2B). We report the results obtained by RET mutation analysis of subjects living in Sardinia, an Italian island whose inhabitants display a peculiar genetic background due to geographic isolation and low immigration rate for several centuries.

DESIGN

Retrospective study reporting data on 67 patients referred during the last 5 years for RET analysis because affected by MTC or first degree relatives of MTC patients.

MAIN OUTCOME

Only three mutations were identified affecting codons 620 (exon 10), 634 (exon 11), and 804 (exon 14); surprisingly, the most prevalent mutation found was V804M (overall prevalence: 59%). This finding is quite different from previous studies carried out in other Caucasian and non-Caucasian populations, in which the frequency of the V804M mutation is consistently reported less than 5%. The phenotype associated to V804M mutation was mostly FMTC (16/17 cases = 94.1%), but in one case (5.9%) primary hyperparathyroidism was found, suggesting a MEN-2A.

CONCLUSIONS

These results underline the importance of the genetic background in the distribution of RET mutations and should be taken into consideration when performing genetic evaluation of MTC patients.

Diabetes incidence in 0- to 14-year age-group in Italy: a 10-year prospective study

OBJECTIVE

The Registry for Type 1 Diabetes Mellitus in Italy (RIDI) Study Group was established to coordinate the registries of type 1 diabetes in Italy. This report is based on 3,606 children younger than 15 years diagnosed with type 1 diabetes and prospectively registered during 1990-1999 by nine centers, covering >35% of the Italian population.

RESEARCH DESIGN AND METHODS

Registries were pooled in four geographic macro-areas: north, central, south, and insular. The completeness of registration was assessed by the capture-recapture method. Poisson regression analysis was used to evaluate temporal trend in incidence.

RESULTS

Large variations in incidence were confirmed not only between Sardegna and the mainland but also among peninsular areas. In Sardegna, there was an excess of boys (the boy-to-girl incidence ratio was 1.4). The overall incidence showed average increases of 3.6% (P <0.001) and 3.7% (P <0.001) per year in peninsular Italy and in Sardegna, respectively. Significant increases in incidence rates were found in boys aged 10-14 years (6.7%, 95% CI 0.5-13.3) and in girls aged 5-9 years (6.6%, 0.5-13.1) living in the southern area. The incidence rate also increased in boys aged 10-14 years (5.0%, 0.3-10) and in girls aged 0-4 years (4.9%, 0.8-9.1) living in Sardegna.

CONCLUSIONS

Italy is a country with large geographical variations in incidence rates of type 1 diabetes. However, the rates are evenly increasing both in the mainland and Sardegna, suggesting that similar environmental factors are operating over populations that have different genetic backgrounds.

Genetic isolates in Corsica (France): linkage disequilibrium extension analysis on the Xq13 region

Genetic isolates with a history of a small founder population, long-lasting isolation and population bottlenecks represent exceptional resources in the identification of genes involved in the pathogenesis of multifactorial diseases. In these populations, the disease allele reveals linkage disequilibrium (LD) with markers over significant genetic intervals, therefore facilitating disease locus identification. This study has been designed to examine the background LD extension in some subpopulations of Corsica. Our interest in the island of Corsica is due to its geographical and genetic proximity to the other Mediterranean island of Sardinia. Sardinian isolates in which the extension of the background LD is particularly high have been recently identified and are now the object of studies aimed at the mapping of genes involved in complex diseases. Recent evidence has highlighted that the genetic proximity between the populations of Corsica and Sardinia is particularly true for the internal conservative populations. Given these considerations, Sardinia and Corsica may represent a unique system to carry out parallel association studies whose results could be validated by comparison. In the present study, we have analyzed the LD extension on the Xq13 genomic region in three subpopulations of Corsica: Corte, Niolo and Bozio, all located in the mountainous north-center of the island. Our results show a strong degree of LD over long distance for the population of Bozio and to a less extent for the population of Niolo. Their LD extent is comparable to or higher than that reported for other isolates.

No association between variation of the FOXP3 gene and common type 1 diabetes in the Sardinian population

Mutations of the forkhead/winged helix transcription factor FOXP3 gene on chromosome Xp11.23 cause a rare recessive monogenic disorder called IPEX (immune dysregulation, polyendocrinopathy, including type 1 diabetes, enteropathy, and X-linked syndrome). FOXP3 is necessary for the differentiation of a key immune suppressive subset of T-cells, the CD4+CD25+ regulatory T-cells. Previously, we reported a significant male-female bias in the common, multifactorial form of type 1 diabetes in Sardinia and evidence of linkage of chromosome Xp11 to the disease. These findings indicate that FOXP3 is a prime functional and positional candidate locus for the common form of type 1 diabetes. In the present study, we initially scanned 82 kb of the FOXP3 region for common polymorphisms, including sequencing all of the coding and functionally relevant portions of the gene in 64 Sardinian individuals. Then the most informative polymorphisms in 418 type 1 diabetic families and in 268 male case and 326 male control subjects were sequentially genotyped and tested for disease association. There is no evidence that variants in the FOXP3 regions analyzed are associated with type 1 diabetes and account for the male-female bias observed in Sardinia. Our data indicate that allelic variation in or near the coding regions of the FOXP3 gene does not have a major role in the inherited susceptibility to the common form of type 1 diabetes.