Mesh : Age Factors Antibodies, Antinuclear / analysis Emigration and Immigration Female HLA-A Antigens / analysis HLA-A11 Antigen HLA-B Antigens / analysis HLA-DQ Antigens / analysis HLA-DR Antigens / analysis HLA-DR Serological Subtypes Humans Male Marital Status Middle Aged Occupational Exposure Scleroderma, Systemic / genetics immunology Sex Factors Silicosis / complications