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

ABSTRACT

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.