[Prevalence of myasthenia gravis in Antioquia, Colombia]. / Prevalencia de miastenia grave en Antioquia, Colombia.

INTRODUCTION: Myasthenia gravis (MG), considered the commonest of all the illnesses that affect neuromuscular transmission, is a disorder in which the autoimmune system attacks the post synaptic acetylcholine receptor proteins in the end plate terminal; it is characterised by weakness and skeletal muscle fatigue, with no anomalies in reflexes, sensitivity or coordination. Epidemiological indicators, such as incidence and prevalence, are not known in Colombia. AIMS. To determine the prevalence of MG among the inhabitants of Antioquia, through the use of the capture recapture method. PATIENTS AND METHODS: The capture recapture method was used for two sources, the Instituto Neurológico de Antioquia and the Hospital Universitario San Vicente de Pa l, which are the most important institutions for the diagnosis of neurological diseases in Antioquia. MG prevalence was calculated using the following formula: p= n/N 105. We examined the data from the period between 1 July 1995 and 30 June 2000 with the aim of identifying subjects who fitted the profile of MG sufferers. RESULTS: General MG prevalence in Antioquia was 27.7 cases per million inhabitants (CI 95%= 23.2 32.2). The male/female ratio was 1:3.77. CONCLUSIONS: The estimated prevalence of MG is lower than that reported in United States and other temperate regions, where it varies between 60 and 150 cases per million. The prevalence of MG is low in Antioquia, as in other tropical areas

[Vascular hereditary dementia CADASIL type in Colombia. III. Linkage analysis to notch3 gene]. / Demencia vascular hereditaria tipo CADASIL en Colombia. III. Análisis de ligamiento a Notch3.

OBJECTIVE: To perform linkage analysis between the Short Tandem Repeats (STR) microsatellite markers D19S923, D19S929, D19S22, which are in strong genetic linkage to Notch3 gene in order to contrast the hypothesis that the vascular hereditary dementia phenotype described in a multigenerational extended pedigree from Colombia correspond to CADASIL (Cerebral Autosomal Dominant Arteriopathy with Subcortical Infarcts and Leukoencephalopathy). Even we know that using techniques as the Single Strand Conformational Polymorphisms (SSCP) could determine mutations in Notch3, the rationality of this approach is that intronic variations could not be defined and that we are interested in determine if some forms of the clinical presentation and its phenotypic variability make part of CADASIL. INTRODUCTION: The CADASIL phenotype is caused by mutations in the Notch3 gene. Clinical features of CADASIL are: 1. Recurrent cerebra-vascular episodes; 2. Migraine history; 3. History of transitory ischemic attack and, 4. Behavior changes and dementia. MATERIAL AND METHODS: By using SIMLINK we showed that the extended genealogy had the enough power to detect significant LOD (logarithm of oods) score values when Notch3 was considered the disorder cause. Linkage analysis was carried out by using parametric and non parametrical methods. The Elston-Stewart general method was used as the parametrical analysis and the sib pair method as the non-parametrical one. We perform simulations changing the affection status codification by including as affected or not including those individuals with migraine. Furthermore, in order to detect the stability of the results, we changed the penetrance values, the genetic frequencies on both, the marker loci and the affection locus. RESULTS: The maximum pair-wise LOD score was 2.04 which was detected at the marker D19S23 with q= 0.11cM. This distance correspond exactly with the Notch3 location. That is 100 times more probable that there is linkage that there is not. In other words this probability could be explained as if the phenotype correspond to CADASIL than to other vascular dementia. The non parametric results were compatibles with the parametric ones. When the migraine symptom was considered as a part of the affected status, the LOD score values showed not linkage. CONCLUSIONS: The results of the linkage analysis to these STR microsatellite markers suggest that the vascular hereditary dementia phenotype described in this family correspond to CADASIL caused by a polymorphism on the Notch3 gene. On the contrary, these same results suggest that the migraine phenotype is not a part of the progressive dementia.

[Prevalence of multiple sclerosis in Colombia]. / Prevalencia de la esclerosis múltiple en Colombia.

INTRODUCTION: Multiple sclerosis (MS) is the commonest demyelinating condition of the nervous system. It is characterized by numerous demyelinating areas or plaques of demyelination which are found dispersed throughout the nervous system. It has been shown that MS is less frequent in tropical regions than in subtropical regions. In Latin America particularly, there are some studies which show this phenomenon. However, in Colombia no studies of prevalence of MS have been done. OBJECTIVE: To determine the prevalence of multiple sclerosis in five provinces of Colombia (Antioquia, Caldas, Santander, Risaralda and Bolivar). PATIENTS AND METHODS: The capture-recapture method was used for two sources to determine the number of cases defined on the criteria of Poser et al seen between July 1995 and June 2000. RESULTS: The prevalence (cases of MS per 100,000 inhabitants) varied between 1.48 in Antioquia (95% CI 1.12; 1.78) and 4.98 in Risaralda (95% CI 3.52; 6.43). Seventy two percent were women. The regions included in this study represented 25% of the population of Colombia. CONCLUSIONS: There is a low prevalence of MS which is as expected in tropical areas. Persons with MS in these regions may be very useful in the study of other factors involved in the aetiology of MS (genetic). The capture-recapture method is an excellent tool for carrying out prevalence studies since it is cheap and requires little time.

Polymorphisms and phyletic relationships of the Paisa community from Antioquia (Colombia).

The allelic frequencies of 14 polymorphic loci were obtained for the Paisa community (Antioquia, Colombia) and compared with those of Caucasoids, Negroids and Amerindians as an approach to better understand its ancestral origin. Data pertaining to Caucasoids included Basques, Spaniards and Jews, historically assumed to be the ancestors of Paisas. These comparisons suggested that the Paisa community is a Caucasoid group with very low Amerindian or Negroid contributions. Spaniards or Basques and, to a lesser extent, Sephardims seem to have been their most probable ancestors.