The mitochondrial DNA A3243G mutation in Portugal: clinical and molecular studies in 5 families.

Out of 90 Portuguese patients with mitochondrial cytopathy, six harbored the A3243G mutation in the mtDNA tRNA(Leu(UUR)) gene ('MELAS mutation'). They had heterogeneous clinical features, including myopathy with stroke-like episodes, progressive external ophthalmoparesis, diabetes mellitus, and subacute encephalopathy. Histochemical and biochemical analyses of muscle biopsies showed abundant ragged-red fibers reacting positively with the cytochrome oxidase stain, and decreased respiratory chain enzyme activities. On average, the proportion of mutated mtDNA was 67% (20-88%) in tissues from patients and 21% (0-49%) in blood from 20 maternal relatives. The proportion of mutated mitochondrial genomes in muscle did not correlate with clinical presentation or duration of disease. This study, the first in Portuguese patients, confirms the frequent occurrence of the A3243G mutation in patients with mitochondrial diseases, and emphasises the usefulness of genetic testing in reaching a correct diagnosis.

[Prenatal diagnosis of congenital cardiomyopathies. Current reality in the south of the country]. / Diagnóstico pré-natal das cardiopatias congénitas. Realidade actual no sul do país.

In order to make an actual perspective about prenatal diagnosis of congenital heart disease in the area of influence of our department, a prospective study including 948 fetus and 185 newborn was done, 348 fetus and 20 newborn evaluated during 1993 (group I) and the remaining during 1994 (group II). In both groups indications for fetal echocardiography were mainly maternal (18%) and familiar (14%) factors, but occurrence of CHD were respectively 2% and 0% for them. Fetal factors for echocardiography account for 7%, namely arrhythmias (7%) and obstetric suspicion of CHD (6%), but occurrence of CHD was respectively 13% and 32% for group I and 36% and 48% for group II. In the newborn with serious CHD, risk factors could be identified in 30% in group I and 36% in group II, being respectively 15% and 7% referred for fetal echocardiography. It is concluded that although a rise in the number of fetus evaluated and a better obstetric accuracy have occurred, the rate of prenatal diagnosis of CHD is still very low, pointing to necessity of continuing our actual policy of teaching and spreading this area, specially in the primary health care units.