[Autoimmune diseases and multiple sclerosis]. / Enfermedades autoinmunes y esclerosis múltiple.

INTRODUCTION: Multiple sclerosis (MS) is a demyelinating disease affecting the central nervous system with an unknown origin, although the immunological system plays a crucial role in its pathogenesis. It has been observed that the relatives of MS patients very often have other autoimmune diseases (ADs) and it has been suggested that there may be susceptibility genes that are common to this group of diseases. AIMS: Our aim was to estimate the prevalence of ADs in first and second degree relatives of patients with MS and to determine the coexistence of other ADs in MS patients. PATIENTS AND METHODS: We selected 251 patients with MS defined by the Poser criteria and face-to-face interviews with the patients and/or their relatives were conducted to investigate the following ADs: MS, rheumatoid arthritis, systemic lupus erythematosus, polyarteritis nodosa, autoimmune thyroid disease (ATD), inflammatory bowel disease, myasthenia gravis, type I diabetes mellitus (DMI) and psoriasis. RESULTS. 29.9% of the patients with MS had a first and/or second degree relative with an AD. Prevalence of ADs in first degree relatives was 15.5%, 30% in familial MS and 40% if the patient had both MS and another AD. The most frequent ADs were: MS 27%, psoriasis 18%, ATD 16% and DMI 15%. 15 patients had MS and another AD: six ATD, three DMI, four psoriasis, one inflammatory bowel disease and one myasthenia gravis. CONCLUSIONS: These findings lend support to the existence of susceptibility genes that are common to the different ADs and would act as risk factors.

[Familial multiple sclerosis in Canary Islands]. / Esclerosis múltiple familiar en Canarias.

INTRODUCTION: Multiple sclerosis (MS) is an autoimmune disease that occurs in genetically predisposed individuals. Its inheritance is polygenic. Genetic epidemiology studies have shown an increased familial aggregation. AIM. To determine the prevalence of familial MS (fMS) in a series of patients from the Canary Islands. PATIENTS AND METHODS: From a cohort of 266 patients with defined MS, during a 6-year period, we investigated prospectively by personal interviews the presence of MS on first and second degree relatives. We analysed as well the presence of HLA DRB1 in affected families, and also clinical and demographic characteristics in fMS and compared them with sporadic MS (sMS). RESULTS: fMS prevalence was 13.9% (27 non-related families with 50 affected individuals). The HLA DRB01*1501 allele were present in 51,8% of familial cases. We could not found either intrafamilial concordance in clinically affected regions and age of onset or clinical evolution. We have not found any phenotypic differences between familial and sMS. CONCLUSIONS: The prevalence of fMS in our series is comparable to that in other Mediterranean populations. Our results do not support that fMS was a different clinical entity of sMS and intrafamilial concordance in its clinical expression.

HLA associations with multiple sclerosis in the Canary Islands.

The study of small island populations has proved informative with respect to the epidemiology and genetics of many complex traits including multiple sclerosis. The class II major histocompatibility antigen DR15 is associated with multiple sclerosis in all groups except Sardinians, where the primary association is with DR4. We compared HLA-DR and -DQ allele frequencies in a representative sample of patients with multiple sclerosis from the Canary Islands with appropriate controls. There was a significant association with DR15 (patients 21/53: 40%: controls 11/55; 20%: chi2=4.09; pc=0.04; relative risk [RR]=1.98). DRB1*1501-DRB5*0101 was present in 17/53 (32%) patients in whom sub-types could be identified compared with 6/55 (11%) controls (chi2=7.21; pc=< 0.01; RR=2.94). All DR15 positive controls carried the DQA1*0102, DQB1*0602 haplotype whereas this was only present in 26/30 patients, suggesting that the primary association is with HLA-DR and not -DQ. We also found a significant increase in HLA-DR4 (16/53 [30%] in patients compared with 7/55 [13%] in controls; pc=0.05). This study contributes a new point on the immunogenetic map of multiple sclerosis in Europe, confirming the primary DR15 association with multiple sclerosis in a previously unstudied population but again highlighting the importance of DR4 in Mediterranean peoples.