We are currently devoted to two different areas: 1) the study of detrimental calcifications characterizing and complicating a number of skeletal disorders, and 2) the study of additional genetic factors associated with the neurological disorder Machado Joseph Disease (MJD). Rheumatic disorders: The etiology and clinical characterization of rheumatic disorders with ectopic calcification is still our main research interest. The investigated disorders are Diffuse Idiopathic Skeletal Hyperostosis (DISH), chondrocalcinosis (CC) and ankylosing spondylitis (AS). Whole genome expression studies in cartilage and synovial tissue biopsies from AS patients are currently being analyzed. The possible AS genetic association of three genes (TNFSF15, ERAP and IL23) is currently being scrutinized in a cohort of Portuguese AS patients and controls. The non classical HLA loci E, G, F, DPA and DPB are also being investigated in AS patients and controls to investigate its possible involvement in the etiology of this disorder. Neurological Disorders: Machado-Joseph disease (MJD/SCA3) is the most common autosomal dominant spinocerebellar ataxia, being caused by a gain of function of ataxin-3, which occurs when an abnormally expanded CAG motif is present in the coding region of ATXN3 gene. In MJD, the causative mutation itself is not sufficient to determine the disease expression, supporting the contribution of additional genetic factors. We have recently focused our efforts on the regulation and transcriptional variation of the ATXN3, and its potential as a modulator of the clinical variability of MJD. Investigation aiming to understand the clinical spectrum of MJD has also resulted in the identification of the Apolipoprotein E gene as a modulator of MJD’s phenotype. Future Research Goals: Rheumatic Disorders: Future work will involve the collection and organization of biological samples, from patients with the rheumatic disorders under study – DISH, CC and AS - in a BioBank. This project will enable the assemblage of important information that can be used for studies of etiology, therapy and clinical outcome. Cell culture of human bone marrow mesenchymal stem cells and human chondrocytes were also recently started; expression studies involving the cultured cells will surely be of major interest. Whole exome sequencing of patients with the phenotype DISH/CC will be performed/analyzed with the objective of identifying mutated genes that can be the underlying cause of the phenotype DISH/CC. Methylation and proteomic studies, with the AS biospecimens collected so far, will hopefully establish new investigation lines and identify new genes of interest. Neurological Disorders:In addition to ApoE, other genetic modifiers remain to be identified. Microarray expression data is being generated for patients, aiming to pinpoint potential new candidates. Presently, accurate measurement tools, to detect the first signs of the disease and subtle therapeutic benefits, are needed for MJD. We are using a non-biased whole-genome approach to detect such changes in peripheral blood of patients. Selected References: Díaz-Peña R, et al. Fine mapping of a major histocompatibility complex in ankylosing spondylitis: Association of the HLA-DPA1 and HLA-DPB1 regions. Arthritis Rheum. 2011 Nov;63(11):3305-12. Evans DM et al; Australo-Anglo-American Spondyloarthritis Consortium (TASC); Wellcome Trust Case Control Consortium 2 (WTCCC2). Interaction between ERAP1 and HLA-B27 in ankylosing spondylitis implicates peptide handling in the mechanism for HLA-B27 in disease susceptibility.Nat Genet. 2011 Jul 10;43(8):761-7. Bruges-Armas J, et al. (2006) Ectopic calcification among families in the Azores: clinical and radiologic manifestations in families with diffuse idiopathic skeletal hyperostosis and chondrocalcinosis. Arthritis Rheum. Apr;54(4):1340-9. Bettencourt, C. & Lima M (2011) “Machado-Joseph Disease: from first descriptions to new perspectives.” Orphanet Journal of Rare diseases, 6(1): 35 Bettencourt, C. et al. (in press). The ε2 allele of APOE increases the risk of earlier age-at-onset in Machado-Joseph Disease (MJD/SCA3). Archives of Neurology. Bettencourt, C et al. (2010 “Increased Transcript Diversity: Novel Splicing Variants of Machado-Joseph Disease Gene (ATXN3).” Neurogenetics, 11(2): 193-202.

Genetics & Arthritis Research