Changes in differential gene expression in fibroblast cells from patients with triple A syndrome under oxidative stress.

The triple A syndrome is a rare autosomal recessive disease caused by mutations in the AAAS gene, which encodes the nucleoporin ALADIN. Recently it was shown that ALADIN plays a role in the import of different factors into the nucleus, which prevent the cell from DNA damage and consecutive cell death under oxidative stress. In order to investigate the changes in differential gene expression in ALADIN-deficient or mutated cells under oxidative stress we used fibroblast cell cultures of triple A syndrome patients and compared these to controls. Analysis of 84 genes, which are associated with oxidative stress and antioxidant defense, showed that 7 genes were significantly and differentially regulated, namely BCL2/adenovirus E1B 19kD-interacting protein 3 (BNIP3), 24-dehydrocholesterol reduc-tase (DHCR24), dual specificity phosphatase 1 (DUSP1), forkhead box M1 (FOXM1), nudix-type motif 1 (NUDT1), prostaglandin-endoperoxide synthase 2 (PTGS2), and scavenger receptor class A, member 3 (SCARA3). Whereas in control cells the expression of DHCR24, FOXM1, NUDT1, and SCARA3 was decreased after paraquat treatment, the expression did not change significantly in patient cells. However, the basal expression of SCARA3 and BNIP3 was significantly higher in patient cells than in controls whereas PTGS2 was less expressed. Furthermore, after paraquat treatment the expression of BNIP3, DUSP1, and PTGS2 was significantly increased in control cells while in patient cells the increase of DUSP1 and PTGS2 expression was significantly reduced. With this work we confirm that cells of triple A patients show an altered induction or downregulation of genes associated with oxidative stress and antioxidant defense.

Facing the genetic heterogeneity in neuromuscular disorders: linkage analysis as an economic diagnostic approach towards the molecular diagnosis.

The identification of an ever increasing number of gene defects in patients with neuromuscular disorders has disclosed both marked phenotype and genotype variability and considerable disease overlap. In order to offer an economic strategy to characterise the molecular defect in patients with unclassified neuromuscular disorders, we designed DNA marker sets for linkage analysis of 62 distinct neuromuscular disorders gene loci, including all known muscular dystrophies, congenital myopathies, congenital myasthenic syndromes and myotonias. Genotyping of marker loci of 140 clinically well-characterised families with unclassified neuromuscular disorders reduced the number of candidates to one or two genes in 49 % of the families. Subsequent mutation analysis and genome-wide scans enabled the determination of the genetic defect in 31 % of the families including the identification of a new gene and a new mutation in an unexpected candidate gene. This highlights the effective application of this approach both for diagnostic strategies as well as for the identification of new loci and genes.