Pruebas de paternidad mediante ADN / DNA paternity test

La investigación científica de la paternidad biológica es un caso especial de la determinación de la relación genética entre dos o más individuos, con base en los principios de la herencia mendeliana simple de los marcadores genéticos, en los que se establecen que los alelos se segregan en la meiosis de forma independiente y discreta. En la evaluación de las relaciones biológicas forenses la prueba de paternidad es el análisis más común, en el cual los perfiles genéticos de dos individuos (o tres si la madre está disponible) son utilizados para comparar la probabilidad relativa de que uno de ellos sea el padre contra la probabilidad de no estar relacionado con la ascendencia del otro individuo analizado. En este caso las repeticiones cortas en tándem (STR) son los marcadores genéticos no ligados más utilizados para la evaluación del parentesco debido a su alto polimorfismo, y a que los resultados obtenidos, usualmente con la aplicación de estadísticas robustas, favorecen la determinación de la relación. Las repeticiones cortas en tándem son típicamente examinadas por la técnica de reacción en cadena de la polimerasa (PCR) mediante plataformas comerciales de múltiples loci de repeticiones cortas en tándem, eficientes y con gran poder de discriminación. Esta revisión describe el estado actual de las pruebas de paternidad mediante ADN, la metodología, el informe de los resultados y su interpretación, para facilitar su comprensión a los profesionales relacionados de una o de otra manera con estos análisis.

Scientific study of biological paternity is a special case of genetic relationship determinationbetween individuals, based on simple mendelian inheritance principles of genetic markers, which establish that the alleles are segregate independently and discreetly during meiosis. The most common analysis of forensic biological relationships evaluation is the paternity test, which the genetic profiles of two individuals (or three if the mother is available) are uses to compare the relative probability of that one of them being the father against the probability of not is ancestrally related to the other analyzed individual. The short tandem repeats (STR) are the commonly used unlinked genetic markers for relationship evaluation due to their high polymorphism. Besides, the results usually favor the determinationof the relationship when a robust statistical analysis is applied. The short tandem repeats analysis is typically by the polymerase chain reaction (PCR), using multiple short tandem repeats loci on commercial platforms, which are efficient and with high discriminating power. This review describes the current state of DNA paternity test, the methodology, the results report, and the interpretation, to facilitate their understanding to related professionals with these types of analysis.

Incidence of transient ischemic attacks in the Belluno Province, Italy. First-year results of a community-based study.

OBJECTIVES: This study formed part of a larger prospective population-based survey on cerebrovascular diseases and aimed to provide reliable and comparable results on TIA incidence and on related risk factors, which could supply investigation objectives and support information for primary and secondary prevention. MATERIAL AND METHODS: We undertook a prospective population-based study in the province of Belluno, an area located in the North-East of Italy where 211,389 people live, utilizing all the possible case-collection sources available in the territory. RESULTS: In the first year of the study (June 1, 1992 to May 31, 1993) 271 patients with a diagnosis of transient ischemic attack were recruited. Among these, we recorded 171 cases of new TIAs. The crude annual incidence rate for new TIAs was 0.80 per 1000, 0.73 per 1000 for men and 0.87 per 1000 for women. After adjustment to the European population, the overall incidence rate decreased to 0.58 per 1000 inhabitants per year. The mean age of new TIA patients was 73.91 years and females were significantly older than males (p < 0.001). A CT scan disclosed an infarct in 21 new TIA patients. CONCLUSION: Our first-year results on new TIAs incidence did not differ from the findings reported in previous population-based studies performed throughout the world and support data as to risk factors for TIA.

Optimizing the time-frame for the definition of bleeding-related death after acute variceal bleeding in cirrhosis.

OBJECTIVE: To identify the best time-frame for defining bleeding-related death after variceal bleeding in patients with cirrhosis. DESIGN: Prospective long-term evaluation of a cohort of 155 patients admitted with variceal bleeding. SETTING: Eight medical departments in seven hospitals in north-eastern Italy. METHODS: Non-linear regression analysis of a hazard curve for death, and Cox's multiple regression analyses using different zero-time points. RESULTS: Cumulative hazard plots gave two slopes, the first corresponding to the risk of death from acute bleeding, the second a baseline risk of death. The first 30 days were outside the confidence limits of the regression curve for the baseline risk of death. Using Cox's regression analysis, the significant predictors of overall mortality risk were balanced between factors related to severity of bleeding and those related to severity of liver disease. If only deaths occurring after 30 days were considered, only predictors related to the severity of liver disease were found to be of importance. CONCLUSION: Thirty days after bleeding is considered to be a reasonable time-frame for the definition of bleeding-related death in patients with cirrhosis and variceal bleeding.

Incidence and prognosis of stroke in the Belluno province, Italy. First-year results of a community-based study.

BACKGROUND AND PURPOSE: We sought to register the incidence rate, risk factors, and case-fatality rate of all the new cases of first-ever-in-a-lifetime stroke in the province of Beluno, Italy. This study aimed to provide an epidemiological survey of cerebrovascular disease that could supply investigative objectives and support information for regional healthcare facilities planning. METHODS: We undertook a prospective population-based study in the territory of the 1st, 2nd, 3rd, and 4th local health units in the province of Belluno, an area located in northeast Italy (population, 211 389). RESULTS: In the first year of the study (June 1, 1992, to May 31, 1993), 474 cases of first-ever stroke were registered. The crude annual incidence rate was 2.24/1000 (2.01/1000 for men and 2.45/1000 for women). After adjustment to the European population, the incidence rate for first stroke was 1.70/1000 per year. The pathological diagnosis was confirmed by a CT scan in 89.5% of cases. Cerebral infarction accounted for 319 cases, while 93 patients suffered a primary intracerebral hemorrhage, 12 patients a subarachnoid hemorrhage, and 50 patients a stroke of unknown origin. The overall 30-day case-fatality rate was 33%, and the mortality within the first week from stroke onset was 23%. The recurrence rate after 1 month was 1.9%. After 1 month, 46% of our patients were functionally independent in activities of daily living. CONCLUSIONS: Our first-year results confirm the fairly high risk for stroke in central and northern Italy and support European findings regarding risk factors for stroke.

Helicobacter pylori and pre-neoplastic and neoplastic gastric lesions.

The spiral bacterium Helicobacter pylori has gained increasing interest as an important gastroduodenal pathogen since its isolation from the gastric mucosa. The presence of Helicobacter pylori in the human stomach is closely associated with chronic gastric inflammatory disease and growing evidence suggests an aetiologic role of this organism in peptic disease. Moreover, epidemiological and histological studies suggest that Helicobacter pylori may be a risk factor for gastric carcinoma and primary gastric lymphoma. Evidence supporting the role of Helicobacter pylori in the pathogenesis of pre-cancerous lesions are reviewed here.

Gastric giardiasis.

AIMS: To assess the prevalence of gastric giardiasis in patients undergoing upper gastrointestinal endoscopy, and to define the clinicopathological correlates of gastric Giardia lamblia infection. METHODS: Consecutive gastric biopsy specimens (n = 15,023) from 11,085 patients, taken at Feltre City Hospital (north eastern Italy) from January 1986 to December 1991, were histologically and immunocytochemically examined for the occurrence of G lamblia trophozoites. Three gastric biopsy specimens from patients harbouring G lamblia infection, who repeated endoscopy before treatment, were also examined electron microscopically. RESULTS: Forty one patients (0.37% of the population study) harboured gastric giardiasis. All patients underwent upper gastrointestinal endoscopy because of dyspepsia, epigastric pain, or abdominal distension. Only two patients had diarrhoea at the time of investigation. Giardiasis was clinically unsuspected in all cases, although the nine patients who also had duodenal biopsies performed had concomitant intestinal giardiasis. Gastric giardiasis was invariably associated with chronic atrophic gastritis. Intestinal metaplasia of the gastric mucosa and Helicobacter pylori infection were found in 32 and 37 of the 41 patients with gastric giardiasis, respectively. CONCLUSIONS: The invariable association of gastric giardiasis with chronic atrophic gastritis, most often showing intestinal metaplasia and H pylori infection, indicates that a decreased gastric acidity is a prerequisite for localisation of G lamblia to the gastric mucosa. Though its possible role as a gastric pathogen remains to be elucidated, these findings suggest that trophozoites should be carefully searched for when examining gastric biopsy specimens showing chronic atrophic gastritis.

Pepsinogen A/pepsinogen C or pepsinogen A multiplied by gastrin in the diagnosis of gastric cancer?

Being pepsinogen A (PGA) levels generally reduced and pepsinogen C (PGC) increased in gastric cancer patients, PGA/PGC ratio has been proposed as a useful marker of the tumour. We tested PGA, PGC and Gastrin (G) levels in patients with gastric cancer (39) and, as a control, in patients with epithelial dysplasia (21), chronic atrophic gastritis (57), gastric ulcer (11) or subjects lacking major or minor endoscopic and microscopic changes at gastroscopy (48). PGA and PGA/PGC levels were significantly reduced in gastric cancer patients (p less than 0.005 and p less than 0.0001 respectively with analysis of variance). Gastrin levels were also reduced in the same patients (p less than 0.005). We therefore adopted an index number (PGA x Gastrin) which was also dramatically reduced in gastric cancer (p less than 0.005); using an arbitrarily chosen cut-off, the "marker" showed very high sensitivity (76%), specificity (96%) and overall accuracy (74%, by Youden J test). We therefore suggest the use of the index number PGA x G in the diagnosis of gastric cancer, as the most useful gastrin presently available, to our knowledge.