Combining HLA-DRB1-DQB1 and Mycobacterium Avium Subspecies Paratubercolosis (MAP) antibodies in Sardinian multiple sclerosis patients: associated or independent risk factors?

BACKGROUND: Amongst Sardinians the human leukocyte antigen (HLA) DRB1-DQB1 haplotypes *15:02-*06:01, *16:01-*05:02, *14:01-4-*05:03 are protective for multiple sclerosis (MS), while *13:03-*03:01, *04:05-*03:01, *03:01-*02:01, *15:01-*06:02 and Mycobacterium avium subspecies paratubercolosis (MAP) are predisposing factors. We studied the correlation between MAP and HLA. METHODS: Five hundred thirty-one patients were searched for anti-MAP2694 antibodies, DRB1-DQB1 genotyping was performed. The haplotypes were classified as predisposing, neutral or protective. RESULTS: Anti-MAP2694 were found in 23 % of subjects carrying one protective HLA versus 32 % without (p = 0.04). CONCLUSIONS: We showed a lower frequency of Abs in patients with protective HLA. These haplotypes could have a protective role for both MS and MAP.

A genetic association study of two genes linked to neurodegeneration in a Sardinian multiple sclerosis population: the TARDBP Ala382Thr mutation and C9orf72 expansion.

Multiple sclerosis (MS) is a chronic disease of the central nervous system characterized by inflammation and accompanied and followed by neurodegeneration. Missense mutations of the TAR DNA Binding Protein gene (TARDBP) located in the chromosome 1p36.22 region, and the hexanucleotide repeat expansions in chromosome 9 open reading frame 72 (C9orf72) are pathogenic in other neurodegenerative diseases such as amyotrophic lateral sclerosis and frontotemporal lobar degeneration. Assuming that TARDBP Ala382Thr mutation and C9orf72 expansion may underlie MS, we evaluated their frequency in a large cohort of MS patients and controls from Sardinia, an island characterized by a very high frequency of MS and an unusual genetic background. Genomic DNA was extracted from peripheral blood and analyzed for the presence of a TARDBP Ala382Thr mutation and C9orf72 expansion. Difference in the frequency of these mutations between MS patients and controls was calculated using the χ(2) test with a standard 2×2 table. The Ala382Thr mutation in its heterozygous state was found in 27/1833 patients (1.4%) and 20/1475 controls (1.3%), whereas C9orf72 pathogenic repeat expansion was found in 6/1014 MS patients (0.6%) and 2/333 controls (0.6%). Individuals carrying the mutations did not present with other neurodegenerative conditions and any differences were reported between groups. TARDBP Ala382Thr mutation and C9orf72 expansion do not play a major role in MS pathogenesis in the Sardinian population. Further analyses on larger samples of MS patients from other populations are needed to better define the possible role of these genes in the complex interplay between neuroinflammation and neurodegeneration in MS.

A genetic study of the FMR1 gene in a Sardinian multiple sclerosis population.

Multiple sclerosis (MS) is a complex autoimmune disease originated from the interplay between genetic and environmental factors. An overlap of clinical and neuroradiological parameters has been described between MS and an adult-onset neurodegenerative disorder, the fragile-X-associated tremor/ataxia syndrome (FXTAS). This syndrome is caused by a trinucleotide premutation expansion of a CGG sequence in the 55-200 repeat range, which is located in the fragile-X mental retardation 1 (FMR1) gene. Female premutation carriers have an increased propensity for immune-mediated disorders. Recently, a case of co-occurrence of MS and FXTAS was reported. Assuming that the premutation expansion may play a role in the MS susceptibility, we evaluated its frequency in a cohort of MS patients from Sardinia, an island characterized by a very high frequency of MS. Nuclear DNA was extracted by standard methods, purified with bisulfite treatment and then amplified twice by PCR with specific primers. Microsatellite analysis was performed and emizogotic subjects were sequenced. Clinical data of patients were also collected. Only 1/755 MS patients exhibited the premutation expansion with a heterozygosis pattern (30/58). No pathogenic repeat expansions (>200 repeats) were found in the entire cohort. Repeats labeled as the gray zone (45-60 repeats) were observed in 15/755 patients. No specific clinical features concerning disease course, disease activity, and disability were reported for these patients. Our results do not support a possible role for premutation or gray zone alleles in MS Sardinian patients. Further studies are needed to better understand the relationship between FXTAS and MS.

Mycobacterium avium subsp. paratuberculosis and multiple sclerosis in Sardinian patients: epidemiology and clinical features.

BACKGROUND: Mycobacterium avium subspecies paratuberculosis (MAP) is an infectious factor recently found in association with multiple sclerosis (MS) in Sardinia. OBJECTIVES: The objectives of this study were to confirm this association and evaluate its role in clinical features. METHODS: A total of 436 patients and 264 healthy controls (HCs) were included. We examined the blood of each individual for MAPDNA and MAP2694 antibodies using IS900-specific PCR and ELISA, respectively. Differences in MAP presence between the MS group and HCs were evaluated. In MS patients, we considered: gender, age, age at onset, duration of disease, course, EDSS, therapy, relapse/steroids at study time, and oligoclonal bands (OBs). RESULTS: MAPDNA and MAP2694 antibodies were detected in 68 MS and six HCs (p = 1.14 × 10(-11)), and 123 MS and 10 HCs (p = 2.59 × 10(-23)), respectively. OBs were found with reduced frequency in MAP-positive patients (OR = 0.52; p = 0.02). MAP2694 antibodies were detected more in patients receiving MS treatments (OR = 2.26; p = 0.01), and MAPDNA in subjects on steroids (OR = 2.65; p = 0.02). CONCLUSION: Our study confirmed the association of MAP and MS in Sardinia. The low OB frequency in MAP patients suggests a peripheral role as a trigger in autoimmunity. MAP positivity might be influenced by steroids and MS therapy. Studies in other populations are needed to confirm the role of MAP in MS.

A novel Cx32 mutation causes X-linked Charcot-Marie-Tooth disease with brainstem involvement and brain magnetic resonance spectroscopy abnormalities.

The objective of this study was to study genetic and phenotypic features of a family with X-linked Charcot-Marie-Tooth consisting of a healthy father, affected mother, two affected sons and one healthy one. A detailed electrophysiological and neuroimaging study, along with sequencing of the Cx32 gene, was performed in all family members. A novel Cx32 123 G>C mutation, determining an aminoacid variation (Glu41Asp), was found in the mother and the affected sons. An alteration in brainstem evoked potentials was found in the mother and one affected son. The affected son, who underwent magnetic resonance imaging, showed symmetrical hyperintensities in paratrigonal white matter, not found in his heterozygous mother, while both subjects exhibited alterations in brain metabolite ratios derived from localised proton-magnetic resonance spectroscopy. These data extend previous findings about central nervous system involvement in Cx32 mutated subjects and further support a functional role of the protein expression in oligodendrocytes.