Interethnic variation of the MMP-9 microsatellite in Amerindian and Mexican Mestizo populations: considerations for genetic association studies

We studied the interethnic variation of the MMP-9 microsatellite in the Mestizo and Amerindian populations using blood samples collected from 435 healthy unrelated individuals from the Central Valley of Mexico. DNA samples were genotyped using the -90 (CA)12-27 repeat near the MMP transcriptional start site using capillary electrophoresis. Our data were compared with those from African, Asian, and European populations (N = 729). Both Mestizo and Amerindian populations were in Hardy-Weinberg equilibrium (P ≥ 0.05). However, strong genetic heterogeneity was found within the Mestizo population (94%, P ≤ 0.0001), which exhibited the highest frequency of Amerindian, African, and European alleles. Likewise, Amerindians showed 6.7% variation among populations (P ≤ 0.0001), suggesting a genetic substructure potentially associated with linguistic affiliations. These findings were corroborated with principal component and population differentiation analyses, which showed relative proximity among the Mestizos and their historical parental populations: Asian (FST ≥ 0.05), European (FST ≥ 0.09), and African (FST ≥ 0.02). Nevertheless, important differences were found between Mestizo and Nahuas (P ≤ 0.0001), and between Mestizo and Me'Phaas (P ≤ 0.0001). These findings highlight the importance of determining local-specific patterns to establish the population variability of MMP-9 and other polymorphic markers. Validation of candidate markers is critical to identifying risk factors; however, this depends on knowledge of population genetic variation, which increases the possibility of finding true causative variants. We also show that dissimilar ethnic backgrounds might lead to spurious associations. Our study provides useful considerations for greater accuracy and robustness in future genetic association studies.

Genetic analysis of the Hispano-Breton heavy horse

Hispano-Breton (HB) is a horse breed with a recent mixed ancestry. It was developed in the 1930s by crossing local mares with Breton draught horses imported from France. Nowadays it is considered to be in a vulnerable situation due to census decline. To genetically characterize the breed and to set up the basis for a conservation programme, we have employed two types of molecular markers: a 347-bp D-loop mitochondrial DNA (mtDNA) fragment and 13 microsatellite loci. A representative sample of 53 HB individuals was analysed together with a sample of 40 Pura Raza Española horses for comparison. Both types of markers revealed a high level of genetic diversity in the HB breed, emphasizing the importance of its conservation. The construction of a phylogenetic network with mtDNA sequences including various Iberian breeds and European heavy horses provided an overall picture of the ubiquitous appearance of HB matrilines with respect to other breeds and revealed the singularity of certain HB maternal lineages. Despite the high allelic richness found in HB horses, microsatellite analysis evidenced a certain degree of inbreeding as a consequence of the type of management generally used for local breeds.

[Antiphospholipid syndrome]

Antiphospholipid syndrome is a well-defined clinical and serological entity characterized by arterial and/or venous thrombosis, recurrent abortion and thrombocytopenia. Anticardiolipin antibodies and lupus anticoagulant are autoantibodies directed against negatively charged phospholipids, which represent the serologic criteria for the diagnosis of the antiphospholipid syndrome. In this review the pathogenic mechanisms of anticardiolipin antibodies, their clinical findings and the current therapeutical strategies are discussed.

[McArdle's disease. Apropos of a case]

McArdle's disease (glycogenosis type V) is a metabolic disorder of hydrocarbons, inherited with autosomic recessive pattern. Biochemically is defined by a myophosphorylase deficiency; clinically it is characterized by exercise intolerance, due to the impossibility of providing energetic substrate to the muscle, myalgias and stiffness. We present a case report of a patient with McArdle's disease and we comment the diagnostic procedures and current therapeutic options.

Comparative effect of synthetic aminoestrogens with estradiol on platelet aggregation

The in vitro effect upon platelet aggregation of estradiol and synthetic estrogens (prolame, buame, and proacame) is described. Prolame and buame produced a dose-dependent inhibition on platelet aggregation. Estradiol and proacame did not show anti-aggregating effects. The results suggest that the use of prolame and buame in estrogen therapy could reduce the risk of thrombo-embolic accidents.

Form discrimination performance of linguistically retarded children

Intra- and intermodal form-discrimination performance was studied in 9 linguistically retarded children. Stimuli were the blocks which comprise the Seguin Form Board. The main findings were that haptic intramodal discriminations were the most difficult of the various conditions and that visual-haptic intermodal discriminations were not significantly more difficult than visual intramodal ones. The first finding may be in part an artifact of simultaneous versus successive stimulation. The second finding was discussed in relation to dissimilar findings from previous studies of various other retarded groups. Methodological problems inherent in previous designs were described, and reasons for the disparity in experimental results were suggested.