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Vitamin D is endowed with a number of biological properties, including down-regulation of inflammation, and might contribute to the pathogenesis of autism spectrum disorders (ASD). Vitamin D binds to the vitamin D Receptor (VDR); the biological activity of the ensuing complex depends on VDR FokI, BsmI, ApaI, and TaqI gene polymorphisms. We evaluated such Single Nucletoide Polymorphismsm (SNPs) in a cohort of 100 Italian families with ASD children. FokI genotype distribution was skewed in ASD children compared with their healthy sibs (Pc = 0.03 2 df) and to a group of 170 Italian healthy women (HC) (Pc = 0.04 2 df). FokI genotype and allelic distribution skewing were also observed in mothers of ASD children compared to HC (Pc = 0.04 2 df). Both Transmission Disequilibrium Test for single loci and haplotype analysis distribution revealed a major FokI (C) allele-mediated protective effect, which was more frequently transmitted (73%) than not transmitted to healthy sibs (P = 0.02). A protective FokI-, BsmI-, ApaI-, and TaqI (CCAG) haplotype was more frequently carried by healthy sibs than by ASD children (P = 1 × 10-4 ; OR: 0.1, 95% CI: 0.03-0.4) too. Finally, a strong gene-dose association of FokI (T) allele with both higher Childhood Autism Rating Scale score (Pc = 0.01) and, particularly, with hyperactivity behavior (Pc = 0.006) emerged in ASD children. Because the protein produced by the FokI (T) allele is transcriptionally less active than that produced by the FokI (C) allele, the reduced biological activity of the vitamin D/VDR complex prevalent in ASD could favor ASD- and maternal immune activation- associated inflammation. Vitamin D supplementation might be useful in preventative and rehabilitation protocols for ASD. Autism Res 2020, 13: 680-690. © 2020 International Society for Autism Research, Wiley Periodicals, Inc. LAY SUMMARY: Vitamin D deficiency and Vitamin D receptor (VDR) polymorphisms are associated with structural and functional brain abnormalities and behavioral disorders. We analyzed the association of VDR gene polymorphisms in a cohort of 100 Italian families with ASD children. A strong correlation between one of the VDR polymorphisms and hyperactivity behavior was evidenced in ASD children. In healthy mothers, the same VDR polymorphism was also correlated with an increased risk of giving birth to children with ASD.

Recent results show that in mainland Italian children with Autism spectrum disorder (ASD), HLA-G coding alleles distribution is skewed and an association between HLA-G*01:05N and ASD is present. Herein, in an independent cohort of Sardinian ASD (sASD) children and their relatives, we verify whether HLA-G allele association with ASD could be confirmed in this genetically peculiar insular population. One hundred children with a diagnosis of ASD, born in Sardinia and of Sardinian descent, 91 of their mothers, and 40 of their healthy siblings were enrolled. DNA sequencing analysis of HLA-G exon 2, 3 and 4 was used to obtain HLA-G allelic frequencies. Alleles distribution was compared with that of continental ASD children and with a control group of Caucasoid couples of multiparous women and their partners from Brazil and Denmark. Skewing of HLA-G allele distribution was replicated in sASD children; in particular, the HLA-G*01:03 allele, associated with reduced fetal tolerogenicity and development of myeloid leukemia, was more common in both ASD groups compared to controls (pc = 1 × 10−3; OR:3.5, 95%CI: 1.8–6.8). However, given the lack of data on HLA-G*01:03 allelic distribution among Sardinian healthy subjects, we cannot exclude a population effect. These data confirm an association of HLA-G locus with ASD development, particularly with those alleles linked to a lower expression of tolerogenic HLA-G protein, thus warranting further studies on HLA-G polymorphism distribution in different ASD populations.

Different isoforms of HLA-G protein are endowed with a differential ability to induce allogenic tolerance during pregnancy. As prenatal immune activation is suggested to play a role in the onset of autistic spectrum disorders (ASD), we evaluated HLA G*01:01-*01:06 allelic polymorphism in a cohort of Italian children affected by ASD (N=111) their mothers (N=81), and their healthy siblings (N=39). DNA sequencing analysis of HLA-G exon 2, 3 and 4 was used to obtain HLA-G allelic frequencies; alleles distribution was compared with that of two control groups of Caucasoid couples of multiparous women and their partners from Brazil and Denmark. HLA-G distribution was significantly different in ASD children compared to both control groups (Brazilian pc=1×10-4; Danish pc=1×10-3). Since HLA-G distribution was similar in the two control groups, their data were pooled. Results indicated that HLA-G*01:01 was significantly less frequent (pc=1×10-4; OR:0.5, 95%CI: 0.3-0.7) whereas HLA-G*01:05N was significantly more frequent (pc=2×10-3; OR:7.3, 95%CI: 2.4-26.6) in ASD children compared to combined controls. Finally, no clear pattern emerged when HLA-G allelic distribution was analyzed in healthy sibs. Notably, HLA-G allelic distribution found in ASD mothers was similar to that observed in the control subgroup of women with recurrent miscarriages, whilst it was significantly different compared to women without miscarriages (pc=6×10-4 df=12). Since HLA-G*01:01 is associated with the elicitation of KIR-mediated tolerogenic responses and HLA-G*01:05N correlates with NK cells activation, results herein indicate that an immune activating milieu during pregnancy is more likely observed in association with the development of ASD, similarly to what occurs in women with recurrent miscarriages.

Vitamin D binding protein (DBP) gene encodes for Gc, an α2 globulin that transports vitamin D metabolites in serum. Given the role of vitamin D in MS onset and disease progression we analyzed the frequencies of three polymorphisms (rs7041, rs4588 and rs2282679) within DBP gene in 701 Italian multiple sclerosis (MS) patients and 831 healthy controls (HC). None of the polymorphisms showed any association with MS onset and progression. Our results suggest that DBP is not involved in the pathogenesis of MS in Italians.

The etiology of Parkinson's disease (PD) is presumably multifactorial and likely involves interactions between genetic and environmental factors, as well as mitochondrial dysfunction, oxidative stress and inflammation. Among environmental factors, Vitamin D was reported to associate with the risk of PD. Vitamin D activity is mediated by its binding to the vitamin D Receptor (VDR), a transcriptional factor for almost 3% of human genes. We genotyped for ApaI, BsmI, TaqI, FokI and rs1989969 VDR single nucleotide polymorphisms (SNPs) a cohort of 406 PD and 800 healthy controls (HC) and found a strong association between the FokI (rs2228570) VDR SNP and PD. Thus, the TT genotype and the T allele resulted associated with PD in the overall analyzed PD population. Gender-based stratification of data indicated that results were maintained for FokI TT genotype and T allele in male PD patients, whereas the FokI T allele alone was confirmed as a risk factor for PD in females. Co-segregation analyses indicated the TaqI ApaI FokI rs1989969 GCTG as a "risk" haplotype for PD. In a subgroup of patients and controls neural Vitamin D and VDR concentration was analyzed in extravesicles (NDEVs) isolated from peripheral blood: no differences emerged between PD and HC. NDEVs results will need to be validated in ampler cohort but we can speculate that, if at neuronal level the amounts of Vitamin D and of VDR are comparable, than the bioavailability of vitamin D and the efficacy of the vitamin D/VDR axis is differentially modulated in PD by VDR SNPs.

MicroRNAs (miRNAs) are small non-coding RNAs that control gene expression by binding their 3' untranslated region (3'UTR) region; these molecules play a fundamental role in several pathologies, including Alzheimer's disease (AD). Synaptosomal-associated protein of 25 kDa (SNAP-25) is a vesicular protein of soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE) involved in neural plasticity and in the exocytosis of neurotransmitters, processes that are altered in AD. Recent results showed that a reduction of SNAP-25 is associated with dementia, and that the rs363050 SNAP-25 polymorphism correlates with cognitive decline and brain atrophy, as well as with the outcome of multistructured rehabilitation in AD patients. We verified the presence of possible correlations between the serum concentration of miRNAs that bind the SNAP-25 3'UTR region and AD. Six different microRNAs (miR-181a-5p, miR-361-3p, miR-23a-3p, miR-15b-3p, 130a-3p and miR-27b-3p) that bind the SNAP-25 3'UTR region were measured by qPCR in serum of AD patients (n = 22), mild cognitive impairment (MCI) subjects (n = 22) and age- and sex-matched controls (n = 22); analysis of results was done stratified for the rs363050 SNAP-25 genotype. Results showed that miR-27b-3p, miR-23a-3p and miR181a-5p serum concentration was significantly reduced in rs363050 SNAP-25 GG homozygous AD patients. Notably, concentration of these miRNAs was comparable in rs363050 AA homozygous AD patients, MCI and healthy controls (HCs). Data herein suggest that miRNAs that bind the SNAP-25 3'UTR region interact with SNAP-25 polymorphisms to influence the neural plasticity typical of AD brains, possibly as a consequence of modulatory activity on SNAP-25 mRNA and/or protein.

Multiple sclerosis (MS) is an autoimmune disease with a multifactorial etiology. The HLA-DRB1*15 allele, is the main genetic risk factor for MS in Caucasians; recent findings showed that the transcription of this molecule is regulated by the vitamin D/vitamin D receptor (VDR) complex. We analyzed SNPs within the VDR gene in association with the HLA-DRB1 locus in 641 MS patients diagnosed according to McDonald criteria and 558 age- and sex-matched healthy controls, to verify possible correlations between the vitamin D/VDR complex, HLA-DRB1, and susceptibility to MS. Results confirmed that HLA-DRB1*15 is a strong predisposing allele (p

The human RAC2 gene encodes a small GTP-binding protein with a pivotal role in immune activation and in the induction of peripheral immune tolerance through restimulation-induced cell death (RICD). Different human pathogens target the protein product of RAC2, suggesting that the gene may be subject to natural selection, and that variants in RAC2 may affect immunological phenotypes in humans. We scanned the genomic region encompassing the entire transcription unit for the presence of putative noncoding regulatory elements conserved across mammals. This information was used to select two RAC2 gene regions and analyze their intraspecific genetic diversity. Results suggest that a region covering the 3' untranslated region has been a target of multiallelic balancing selection (or diversifying selection), and three major RAC2 haplogroups occur in human populations. Haplotypes belonging to one of these clades are associated with increased susceptibility to multiple sclerosis (P = 0.022) and earlier onset of disease symptoms (P = 0.025). This same haplogroup is significantly more common in patients with Crohn's disease compared with healthy controls (P = 0.048). These data reinforce recent evidences that susceptibility alleles/haplotypes are shared among multiple autoimmune disorders and support a causal "role for RAC2" variants in the pathogenesis of autoimmune diseases. Other genes with a role in RICD have previously been associated with autoimmunity in humans, suggesting that this pathway and RAC2 may represent novel therapeutic targets in autoimmune disorders.

Previous studies reported an association with multiple sclerosis (MS) of distinct HLA-class I markers, namely HLA-A*02, HLA-Cw*05 and MOG-142L. In this work, we tested the association with MS of A*02 and Cw*05 in 1273 Italian MS patients and 1075 matched controls, which were previously analyzed for MOG-142, and explored the relationship among these three markers in modulating MS risk. HLA-A*02 conferred a statistically robust MS protection (odds ratio, OR=0.61; 95% confidence intervals, CI=0.51-0.72, P10(-9)), which was independent of DRB1*15 and of any other DRB1* allele and remained similar after accounting for the other two analyzed class I markers. Conversely, the protective effect we previously observed for MOG-142L was secondary to its linkage disequilibrium with A*02. Cw*05 was not associated considering the whole sample, but its presence significantly enhanced the protection in the HLA-A*02-positive group, independently of DRB1: the OR conferred by A*02 in Cw*05-positive individuals (0.22, 95% CI=0.13-0.38) was significantly lower than in Cw*05-negative individuals (0.69, 95% CI=0.58-0.83) with a significant (P=4.94 x 10(-5)) multiplicative interaction between the two markers. In the absence of A*02, Cw*05 behaved as a risk factor, particularly in combination with DRB1*03 (OR=3.89, P=0.0006), indicating that Cw*05 might be a marker of protective or risk haplotypes, respectively.

Analyses of a 6-Mb region spanning the human leukocyte antigen (HLA) region from the HLA-DR to the HFE gene were performed in 37 families of Sardinian ancestry, all of whom had at least one autistic child, to identify genetic markers associated with autism spectrum disorders (ASD) development. In particular, four microsatellites (MIB, D6S265, MOGc, and D6S2239) and three single-nucleotide polymorphisms (SNPs; two in positions -308 and -238 in the promoter of the TNF-alpha and SNP rs2857766 [V142L] in exon 3 of the MOG gene) were analyzed. An intrafamilial case-control method (affected family-based controls) and transmission disequilibrium test analysis were used to evaluate the association of microsatellite and SNP markers with ASD-affected children. Results indicated positive associations with ASD for D6S265*220 (p0.01) and MOGc*131 (p0.05) and negative associations for MOGc*117 and MIB*346 alleles (p0.01) in ASD children. Polymorphism haplotype analysis indicated that D6S265 allele *220 and MOGc allele *131 were significantly more likely to be transmitted together, as a whole haplotype, to ASD children (p0.05). Conversely, the D6S265*224-MOGc*117-rs2857766(G) haplotype was significantly less frequently transmitted to ASD children (p0.01). The results present novel gene markers, reinforcing the hypothesis that genetic factors play a pivotal role in the pathogenesis of ASD.

Although HLA-DQ genes are the major celiac disease (CD) susceptibility genes, results from Finnish families suggest that not all DQ2-encoding haplotypes confer equal susceptibility to CD, implying the effect of other gene(s) in the HLA region. The aim of the present work was to extend and confirm the aforementioned results in a southern European population ( Italian) and to better localize the additional risk factor/s. The association of nine loci spanning the HLA region from DR to HFE, 4.5-Mb telomeric of HLA-A, was tested. The analysis was performed by comparing marker frequencies in DR3-DQ2 haplotypes transmitted and non-transmitted to the affected offspring in 156 Italian CD families selected for having at least one DR3-positive parent. The same analysis was performed independently in 101 Finnish CD families selected with the same criteria. Three alleles, MICA-A5.1, MICB-CA24 and MIB-350, all characteristic of the B8-DR3 extended haplotype, showed a significantly increased frequency in DR3 transmitted haplotypes in the Italian families. DR3 haplotypes carrying the combination of these alleles conferred an approximate fourfold increased CD risk. B8-DR3 transmitted haplotypes were significantly more conserved telomerically down to the MIC-Class I region. Similar results were seen in the Finnish families. The major conclusion that holds true in both populations is that, while DQ2 is an absolute requirement for the development of CD, the presence of an additional genetic factor within the MIC-Class I region confers an approximate 4-fold increased risk of the disease.

The HLA-DQA1*05 with DQB1*02 alleles are a major risk factor for celiac disease (CD). To search for additional human leukocyte antigen (HLA) risk factors, we looked on the DR3-DQ2 risk haplotype, selected because it carries both DQ risk alleles in cis and is the more represented among CD patients. In a European consortium, we identified 109 families with a parent homozygous for DQA1*05-DQB1*02. We typed ten microsatellites in the extended HLA complex, and applied the homozygous-parent transmission disequilibrium test (HPTDT) and extended-TDT to transmissions from homozygous parents. These methods eliminate confounding due to linkage disequilibrium between candidate disease loci and the known risk factor DQA1*05-DQB1*02, and are favorable when sufficient families are available. We did not find evidence of association with any single marker or allele, although weak evidence for additional risk was observed, represented by preferential transmission of six adjacent markers. We tested the largest ever reported HPTDT population in CD, providing unprecedented power. We did not find significant evidence of additional risk-modifying factors on the DR3 haplotype, independent of DQA1*05-DQB1*02, although a weak tendency was observed for the B8-DR3 haplotype. This effect should be tested in large populations with significant representations of both B8-DR3 and non-B8 DR3 haplotypes.

Background The temporal coordination of biological processes into daily cycles is a common feature of most living organisms. In humans, disruption of circadian rhythms is commonly observed in psychiatric diseases, including schizophrenia, bipolar disorder, depression and autism. Light therapy is the most effective treatment for seasonal affective disorder and circadian-related treatments sustain antidepressant response in bipolar disorder patients. Day/night cycles represent a major circadian synchronizing signal and vary widely with latitude. Results We apply a geographically explicit model to show that out-of-Africa migration, which led humans to occupy a wide latitudinal area, affected the evolutionary history of circadian regulatory genes. The SNPs we identify using this model display consistent signals of natural selection using tests based on population genetic differentiation and haplotype homozygosity. Signals of natural selection driven by annual photoperiod variation are detected for schizophrenia, bipolar disorder, and restless leg syndrome risk variants, in line with the circadian component of these conditions. Conclusions Our results suggest that human populations adapted to life at different latitudes by tuning their circadian clock systems. This process also involves risk variants for neuropsychiatric conditions, suggesting possible genetic modulators for chronotherapies and candidates for interaction analysis with photoperiod-related environmental variables, such as season of birth, country of residence, shift-work or lifestyle habits. Electronic supplementary material The online version of this article (doi:10.1186/s13059-014-0499-7) contains supplementary material, which is available to authorized users.

HLA-G expressed by the trophoblast ligates KIR molecules expressed by maternal NK cells at the uterine fetal/maternal interface: this interaction is involved in generating immune tolerance during pregnancy. A 14-bp insertion in the HLA-G 3'-UTR associates with significantly reduced levels of both HLA-G mRNA and soluble HLA-G, thus hampering the efficacy of HLA-G-mediated immune tolerance during pregnancy. Because prenatal immune activation is suggested to play an important role in the onset of autistic spectrum disorders (ASD) we performed an in-depth evaluation of HLA-G polymorphisms in a well-characterized cohort of Italian families of ASD children. Results showed that frequency of both homozygous 14bp+/14bp+ genotype and 14bp+ allele was significantly higher in ASD children and their mothers compared to controls (p

Summary The present study is a contribution to the definition of the linkage disequilibrium relationship of MICA and MICB with adjacent loci and to the characterization of extended HLA haplotypes. These issues are of importance for the identification of disease associations and for a better definition of donor–recipient compatibility in bone-marrow grafts through the typing of haplospecific markers. The distribution of the five alleles of MICA and the 13 alleles of MICB microsatellites, located, respectively, in MICA transmembrane exon 5 and in MICB intron 1, was examined in 133 healthy Italian individuals previously typed for HLA class I, class II and complement loci and for the TNFa microsatellite. The MICB microsatellite was also analysed in 49 HTCLs for which MICA typing was already available. Very strong linkage disequilibria with HLA-B and TNFa were detected in the Italian population for both MICA and MICB microsatellite alleles, in spite of the high mutability rate of the larger MICB alleles. Some strong associations were also detected between MICB and DRB1. The strongest associations (P 0.7) were those of MICA-A4 with HLA-B18, B27 and TNFa1, MICA-A5 with HLA-B35, B61 and B62, MICA-A5.1 with HLA-B7, B8, B13, B63 and MICB-CA24, MICA-A6 with HLA-B51, MICA-A9 with HLA-B39, B57 and TNFa2, MICB-CA14 with HLA-B14, B27 and TNFa1, MICB-CA15 with HLA-B52, TNFa4 and TNFa13, MICB-CA17 with HLA-B7 and TNFa11, MICB-CA18 with HLA-B13 and TNFa7, MICB-CA22 with HLA-B57, and MICB-CA24 with HLA-B8 and TNFa2. From pairwise associations in the random panel and results for the homozygous cell lines it was possible to deduce the MICA and MICB microsatellite alleles present in many of the well-known Caucasoid extended haplotypes.

The majority of patients with acute promyelocytic leukemia (APL) possess either a bcr1 or a bcr3 type fusion between PML and RARalpha genes. The junction sequences may possibly be a target for immune response and influence susceptibility to the disease. In this case, HLA class I allele frequencies would be different between bcr1 and bcr3 patients. To test this hypothesis, we typed 102 APL patients for HLA-A, -B and -Cw alleles. The A*1, A*30, B*51, B*41, Cw*0602, and Cw*1701 alleles showed a different distribution between bcr1 and bcr3 patients, but in no case was this statistically significant after correction for the number of comparisons or was confirmed in an independent panel. Moreover, no difference was detected between bcr1 and bcr3 when HLA alleles were grouped according to their peptide binding specificities. Comparing HLA frequencies, clinical features at diagnosis and clinical outcome of the 64 patients homogeneously treated with all-trans retinoic acid and idarubicin (AIDA protocol) we observed a statistically significant association between HLA-B*13 and risk of relapse by univariate and multivariate regression analysis. Should this finding be confirmed in larger future studies, this observation would be of outmost importance in identifying patients at high risk of relapse in which more aggressive consolidation therapies should be used.

The presence of haplotype-specific recombination sites can be determined by analyzing the conservation of extended haplotypes in the population. This approach considers all meioses in the history of the population and requires the presence of characteristic markers that easily allow the identification of the haplotype or of its recombined segments. The recombination breakpoint can then be mapped by looking for shared alleles between haplotypes selected through the specific marker/s. We identified a rare perfect tandem duplication of a 145 base pair segment in the LTA promoter, which tags a B60 (B60D) haplotype. The duplication was detected in 16/90 B60 + Europeans, while absent in 101 B60 + Orientals. The conservation of the class I end and the extreme variability of the class II end suggested that the present-day B60D haplotypes originated from an ancestral haplotype by recombination events centromeric to the duplicated sequence. Through a fine mapping using markers of the HLA central region a preferential recombination site was localized in the 60 kilobase interval between TNFd,e, and D6S273/K11 Amicrosatellite loci (i.e., between LST1 and BAT3 genes). This site behaves as a potent recombination enhancer leading to fragmentation in most of the extant B60D haplotypes and can be considered responsible for their “instability”. In the relatively recently founded Finnish population, where the LST1/BAT3 interval recombination has probably not yet had the chance to occur, a founder effect can explain the presence of a rare DP (DPB1 * 1601) allele in most B60D haplotypes in this population.

The activity of natural killer (NK) cells is modulated by the interaction between killer-cell immune globulin-like receptor (KIR) proteins and their cognate HLA ligands; activated NK cells produce inflammatory cytokines and mediate innate immune responses. Activating KIR/HLA complexes (aKIR/HLA) were recently suggested to prevail in children with autism spectrum disorders (ASD), a neurodevelopmental syndrome characterized by brain and behavioral abnormalities and associated with a degree of inflammation. We verified whether such findings could be confirmed by analyzing two sample cohorts of Sardinian and continental Italian ASD children and their mothers. Results showed that aKIR/HLA are increased whereas inhibitory KIR/HLA complexes are reduced in ASD children; notably this skewing was even more significant in their mothers. KIR and HLA molecules are expressed by placental cells and by the trophoblast and their interactions result in immune activation and influence fetal, as well as central nervous system development and plasticity. Data herein suggest that in utero KIR/HLA immune interactions favor immune activation in ASD; this may play a role in the pathogenesis of the disease.

Synaptosomal-associated protein of 25 kD (SNAP-25), a protein participating in the regulation of synaptic vesicle exocytosis and in calcium homeostasis, was recently involved in neuropsychiatric conditions. Because alterations affecting the homeostasis of calcium are described in patients affected by autism spectrum disorders (ASD) we investigated a possible involvement of SNAP-25 in ASD by evaluating five SNAP-25 gene polymorphisms in a cohort of 67 ASD children. Data analyzed in relationship with clinical outcomes and compared to those of 205 healthy sex-matched children did not reveal significant differences. Further analyses nevertheless showed the presence of highly significant associations of the rs363043 (CT) genotype, localized in the intron 1 region that affects the transcription factor binding sites of the SNAP-25 gene, with both increasing CARS ( p = 0.001) and hyperactivity scores ( p = 0.006). The finding that polymorphisms of the SNAP-25 gene, a gene involved in neurotransmission and regulation of calcium homeostasis, are associated with the degree of hyperactivity in children with ASD, reinforces the hypothesis that alterations of these mechanisms play a pivotal role in the events leading to ASD-associated behavioral impairment. Modulation of these processes could result in novel therapeutic strategies.

To verify correlations between HLA and autism spectrum disorders (ASD) we studied 61 Italian families with an ASD child; results showed such correlation in 65% of cases. Case-control and TDT analysis of intrafamilial transmission of SNPs, Msats, and HLA markers surrounding the α and β blocks, indicated significant positive associations for MOGc*131 and D6S2239*105 alleles in ASD, and a negative association of MIB *332 allele in healthy siblings. Polymorphism haplotype analysis demonstrated that two haplotypes comprising the TNF-238(G)-TNF-308(G)-MIB*332-HLA-B*38-HLA-Cw*12 and the D6S265*218-HLA-A*23-MOGc*131-rs2857766(G) alleles are more frequently transmitted to ASD. MOGc and MIB loci are linked with ASD in Italian patients.

Several studies suggest that the histocompatibility complex (HLA) class I region harbours genes modulating multiple sclerosis (MS) susceptibility independently from the effect of class II alleles. A candidate gene in this region is MOG, encoding the myelin oligodendrocyte glycoprotein. A significant association with the missense variation V142L (rs2857766) was previously reported in a small sample of 50 Italian MS patients. We confirmed this result in two independent Italian sample sets consisting of 878 MS patients and 890 matched controls (P=6.6 x 10(-4)) and 246 trio families (P=1.5 x 10(-3)). The comparison of genotype frequencies suggested a dominant-protective effect of L142. In the combined sample sets L142 conferred an odds ratio (OR)=0.70 (95% confidence interval (CI): 0.60-0.82) that remained similar after accounting for HLA-DRB1(*)15 carrier status. The association with MOG V142L was still significant after conditioning for all DRB1 alleles (P=0.035). Eleven additional single nucleotide polymorphisms in the MOG gene (namely -1077T/C, -910T/C, -875A/G, -93T/C, S5S, Indel L22, V145I, +814C/T, +900A/G, +1024A/T, +1059C/T), two microsatellites in the MOG 5' flanking (MOGCA) and 3' untranslated (MOGTAAA) regions and four microsatellites in the HLA-class I region, from HLA-B to HFE, (namely MIB, D6S265, D6S1683 and D6S2239) were tested by transmission disequilibrium test in 199 trio families. None of these polymorphisms or of their haplotypic combinations showed a significant transmission distortion, in the absence of V142L. In conclusion, MOG V142L, or an untested variant in tight-linkage disequilibrium with it, is an independent MS susceptibility-modulating factor in the HLA class I region.

Genetic polymorphisms of immunorelevant genes may modulate occurrence or clinical features of multifactorial diseases. PECAM-1 is an adhesion molecule crucial for transmigration of cells from blood to tissues, but its genetic contribution to multifactorial diseases has never been investigated. We have identified and characterized a tetranucleotide repeat polymorphism within the third intron of PECAM-1. In a cohort of healthy controls (HC), we found 10 alleles. An assessment of the association of this polymorphism with multiple sclerosis (MS) showed similar allele and genotype frequencies in HC and MS patients as well as in MS patients differing for the gravity of their disease course. We conclude that although potentially able to affect organ-specific autoimmune diseases, this new PECAM-1 polymorphism, does not seem to contribute to the genetic background of MS.

Coeliac disease (CD) is a multigenic and multifactorial enteropathy triggered by gluten-composing proteins. A possible involvement of the intestinal Aminopeptidase N (APN) was investigated by an association analysis. SSCP analysis detected four variants at position 281, 378, 956 and 2957 (referred to no. g178535, GenBank) that were studied in 193 Italian CD families. The haplotypic combinations were determined from family segregation and pairwise linkage disequilibria (D' = D/Dmax) between the polymorphic sites were calculated. Significant D' values ranged between 0.78 and 0.31. Association with CD was tested by TDT (Transmission Disequilibrium Test) utilizing as markers the nucleotide substitutions and their haplotypic combinations. No statistically significant transmission distortion to the probands or to their clinically silent sibs was observed. Our data exclude an involvement in CD of the tested markers and of further undetected variation in strong linkage disequilibrium (D' approximately equal to 1) with them. The power of the test was not adequate to detect an association with an unknown polymorphism which is not in complete linkage disequilibrium with those analysed.