Discerning non-disjunction in down syndrome patients by means of GluK1-(AGAT) n and D21S2055-(GATA) n microsatellites on chromosome 21.

Introduction: Down syndrome (DS), the leading genetic cause of mental retardation, stems from non-disjunction of chromosome 21. Aim: Our aim was to discern non-disjunction in DS patients by genotyping GluK1-(AGAT) n and D21S2055-(GATA) n microsatellites on chromosome 21 using a family-based study design. Materials and Methods: We have used a PCR and automated DNA sequencing followed by appropriate statistical analysis of genotype data for the present study Results and Discussion: We show that a high power of discrimination and a low probability of matching indicate that both markers may be used to distinguish between two unrelated individuals. That the D21S2055-(GATA) n allele distribution is evenly balanced, is indicated by a high power of exclusion [PE=0.280]. The estimated values of observed heterozygosity and polymorphism information content reveal that relative to GluK1-(AGAT) n [H obs =0.286], the D21S2055- (GATA) n [H obs =0.791] marker, is more informative. Though allele frequencies for both polymorphisms do not conform to Hardy-Weinberg equilibrium proportions, we were able to discern the parental origin of non-disjunction and also garnered evidence for triallelic (1:1:1) inheritance. The estimated proportion of meiosis-I to meiosis-II errors is 2:1 in maternal and 4:1 in paternal cases for GluK1-(AGAT) n , whereas for D21S2055-(GATA) n , the ratio is 2:1 in both maternal and paternal cases. Results underscore a need to systematically evaluate additional chromosome 21-specific markers in the context of non-disjunction DS.

Nivel de dificultad y poder de discriminación del tercery quinto examen parcial de la cátedra de cito-histología2007 de la carrera de medicina de la UMSA / Level of difficulty and discrimination power of the third and fifth partial examination of the chair of cyto-histology 2007 of the medical career of UMSA

Objetivo:Determinar el nivel de dificultad y el índice de discriminación del tercer y quinto examen parcial de Cito-Histología. Diseño de investigación:Descriptivo de corte transversal. Lugar:Cátedra de Cito-HistologíaMuestra:388 exámenes de estudiantes que dieron el tercer parcial y 350 el quintoMétodo:Los datos se recolectaron a través de un formulario, el nivel de dificultad y poder de discriminación se obtuvieron por formulasestablecidas.Resultados:La media de dificultad del tercer parcial fue de 0,34, siendo medianamente difícil, la media del quinto fue 0,54 siendo de dificultad media. Lamedia del índice de discriminación del tercer parcial fue 0,57 y 0,45 del quinto, el coeficiente de discriminación fue 0,44 para el tercero y 0,54para el quinto, así, ambos parciales tuvieron una calidad excelente. Conclusiones:Según el nivel de dificultad del tercer parcial fue más difícil que el quinto, éste último estuvo dentro de parámetros esperados, el tercer parcialno tuvo reactivos fáciles. Ambos parciales discriminaron positivamente, una pregunta del tercer parcial debería descartarse y dos del quintorevisarse a profundidad.

Objective: To determine the level of difficulty and the power of discrimination of the third and fifth partial exam in Cytohistology Research Design: Descriptive, cross sectional Location: Chair of Cytohistology Sample:The students who took the third and fifth partial exams: 388 for the third and 350 for the fifth. Method: The data were collected by means of a form, the difficulty level and power of discrimination were calculated by established formulas Results: The average difficulty of the third partial exam was 0.34, qualified as moderately difficult. The average difficulty of the fifth partial exam was 0.54 which qualifies for half difficult. The average index of discrimination of the third partial exam was 0.57 and of the fifth 0.45. The discrimination quotient was 0.44 for the third and 0.54 for the fifth exam, and both partials were of excellent quality. Conclusions: Considering the difficulty level, the third partial exam was more difficult than the fifth the latter being within expected parameters . Both partials discriminated positively, one question of the third partial should be removed, and two questions of the fifth test should be reviewed in depth.

Polymorphism and forensic efficiency of 5X-STR loci in Korean / 대한법의학회지

This study intends to examine the polymorphism of 5 STR loci inX-chromosome (GATA172D05, HPRTB, DXS8377, DXS101, HumARA) and to evaluate usefulness of them in forensic identification. 100 unrelated Korean men and women were selected. DNA was extracted from these sample and PCR was performed to amplify it. And using automated DNA sequencer and computer program, the genotype and allele frequency of them were investigated and analyzed. The following results were obtained: 1. The genetic analysis of 5 STR loci inX-chromosome was performed with quadruplex PCR for GATA172D05, HPRTB, DXS8377, HumARA and monoplex PCR for DXS101. 2. Polymorphism information content of 5 loci is higher than 0.5, the high information content is observed. The heterozygosity is higher in DXS8377, DXS101, HumARA than others. 3. The power of discrimination is revealed high in all 5 loci in women, but in men DXS8377 and HumARA is higher than others. 4. The mean exclusion chance is revealed high in DXS8377 and HumARA which have more alleles than others in trio case and motherless case. 5. The difference of allele frequency is observed with other population group in DXS8377, DXS101, HumARA of Korean population group. Based on the results of this study, the allele frequency and population data of 5 STR loci inX-chromosome may be useful in forensic investigation.