Composición genética de la población chilena: distribución de polimorfismos de DNA mitocondrial en grupos originarios y en la población mixta de Santiago / Genetic composition of the chilean population: analysis of mitochondrial DNA polymorphisms

Background: The analysis of mitochondrial DNA restriction site polymorphisms assigns most Latin American aborigines to four haplogroups. These are characterized by determined polymorphic restriction sites and a deletion of 9 base pairs in the intergenic region V. Aim: To study the distribution of mitochondrial DNA haplogroups in Chilean aboriginal groups, as well as in the mixed population of Santiago. Material and methods: One hundred twenty Aymara subjects and 23 Atacame-o subjects from the Northern part of Chile and 162 randomly chosen subjects residing in Santiago were studied. DNA was extracted from peripheral lymphocytes. Mitochondrial DNA was amplified by means of polymerase chain reaction. Results: The frequency of haplogroup B decreases from north to south. Aymaras in the north have the highest frequency (64 percent) and it is absent among the Yamanas (previously studied) in the extreme South. Haplogroups C and D show an inverse tendency. It is noteworthy that 84 percent of mitochondrial haplogroups of the mixed population of Santiago are of Amerindian origin whereas the Y-chromosomes are mainly European. Conclusions: The peculiar distribution of haplotypes indicate that the population of Santiago is the result of an asymmetric mating system in which the females ancestors were mainly Amerindian and the male ancestors mainly European

Mialgias post ejercicios como forma de presentación de una distrofinopatía / Post exercise myalgias as form of dystrophynopathy

Cramps and myalgias are frequent presentations of many disorders whose diagnosis is generally difficult. Among the unusual causes stand the milder phenotypes of dystrophinopathies, which are caused, just as Duchenne and BeckerÕs dystrophy, by mutations in the dystrophin gene. An 8 year-old boy presented severe muscle pain on exercise and serum rise in creatine kinase over 1000 U/l. He had normal muscle power and mild calf hypertrophy. The molecular analysis by polymerase chain reaction (PCR) of the dystrophin gene showed deletions of exons 45 to 51. Dystrophin analysis by Western blot revealed a dystrophin of reduced quantity and molecular weight. Emphasis is made to include dystrophinopathies in the differential diagnosis of myalgias and the usefulness of molecular genetic techniques in the identification of these disorders