ABSTRACT
El descubrimiento del ADN libre fetal circulando en sangre materna ha revolucionado la práctica de la Obstetricia y cambiado el paradigma del diagnóstico prenatal. En los últimos 5 años hemos avanzado del tamizaje de aneuplodías con muchos falsos positivos a uno mucho más efectivo y con cifras de falsos positivos muy bajas. Este es, sin duda, el mejor método de tamizaje actual que se tiene en Obstetricia.
The discovery of cell free fetal DNA (cff-DNA) in maternal circulation has profoundly changed the clinical practice of Obstetrics and knocked down an old paradigm in prenatal diagnosis. Over the past five years screening for chromosomal abnormalities has moved from one with a high false positive rate into another more effective and at lower false positive rate. Undoubtedly, this test is the best effective screening tool in Obstetrics.
ABSTRACT
Objetivos: Evaluar nuestra experiencia en la aplicación del algoritmo de la Fundación de Medicina Fetal (FMF) en el tamizaje prenatal de aneuploidías en el primer trimestre en una población no seleccionada. Diseño: Estudio descriptivo, retrospectivo, transversal. Institución: Servicio de Medicina Fetal, Clínica Santa Isabel, Lima, Perú. Participantes: Gestantes y sus fetos. Intervenciones: Entre el 1 de marzo de 2012 y el 24 de setiembre de 2012, en 324 pacientes con 11 a 13+6 semanas de edad gestacional y fetos con longitud corona nalga (LCC) de 45 a 84 mm, se logró medir la translucencia nucal (TN) mediante ecografía transabdominal. Principales medidas de resultados: Factibilidad de la aplicación del algoritmo de la FMF en el tamizaje de 11 a 13+6 semanas. Resultados: La curva observada de los valores de la TN en relación a la LCC se ajustó a la ecuación cuadrática descrita por la FMF, y la distribución de las medidas presentó una disposición normal, teniendo la mediana una desviación de 0,2 mm respecto al esperado. El porcentaje de valores por encima de la mediana fue 43,3%. Se observó una TN >percentil 95 en 4,6% de casos y TN ≥ 3,5 mm en 1,2%. Se encontró un valor de riesgo por encima del punto de corte de 1:100 en 10 casos para T21 y en un caso para T13. Los resultados del estudio citogenético en tres pacientes fueron un cariotipo femenino normal, una trisomía 18 y una trisomía extra-estructural (47XY+mar). Conclusiones: Nuestros resultados concuerdan con lo comunicado en la literatura y muestran que es factible la aplicación del algoritmo de la FMF en el tamizaje de 11 a 13+6 semanas en un entorno de práctica clínica, en nuestro medio.
Objectives: To determine our experience in applying the Fetal Medicine Foundation (FMF) algorithm for first trimester aneuploidy screening in an unselected population. Design: Descriptive, retrospective, cross-sectional study. Setting: Fetal Medicine Service, Clinica Santa Isabel, Lima, Peru. Participants: Pregnant women and their fetuses. Interventions: Between March 1 and September 24 2012, nuchal translucency (NT) was measured by transabdominal ultrasound in 324 women with 11-13+6 weeks pregnancies and crown-rump length (CRL) between 45.0-84.0 mm. Main outcome measures: Factibility of FMF algorithm in 11-13+6 weeks screening. Results: NT curve in relation to CRLs was consistent with the quadratic equation described by FMF, and measurements followed a normal distribution with median deviation 0.2 mm lower than expected. The percentage of values above the median was 43.3%. A TN >95th percentile was observed in 4.6% of cases and TN ≥3.5 mm in 1.2%. A risk value above the 1:100 cut-off was found in 10 cases for T21 and in one case for T13. Cytogenetic study was performed in 3 patients; results were one normal female karyotype, one trisomy 18 and one extra-estructural trisomy (47XY+mar). Conclusions: Results agree with literature reports and show feasibility of FMF algorithm application in 11-13+6 weeks screening in a clinical practice setting in our country.
ABSTRACT
BACKGROUND: Dysfunctions in the folate metabolism can result in DNA hypomethylation and abnormal chromosome segregation. Two common polymorphisms of this enzyme (C677T and A1298C) reduce its activity, but when associated with aneuploidy studies the results are conflicting. The objective of the present study is to analyze the MTHFR gene polymorphisms in women with Turner Syndrome and in a control group, correlating the findings to the chromosomal aneuploidy. METHODS: The study comprised 140 patients with Turner Syndrome, of which 36 with chromosome mosaicism and 104 non-mosaics, and a control group of 209 fertile and healthy women without a history of any offspring with aneuploidy. Polymorphisms C677T and A1298C were studied by RFLP-PCR and the results were statistically analyzed. RESULTS: The frequency of genotypes MTHFR 677CC, 677CT and 677TT in the patients with Turner Syndrome and chromosome mosaicism was, respectively, 58.3 percent, 38.9 percent and 2.8 percent. Among the patients with non-mosaic Turner Syndrome, 47.1 percent presented genotype 677CC, 45.2 percent genotype 677CT, and 7.7 percent genotype 677TT. Among the 209 individuals of the control group, genotypes 677CC, 677CT and 677TT were found at the following frequencies: 48.3 percent, 42.1 percent and 9.6 percent, respectively. As for polymorphism A1298C, the patients with Turner Syndrome and chromosome mosaicism presented genotypes 1298AA, 1298AC and 1298CC at the following frequencies: 58.3 percent, 27.8 percent and 13.9 percent, respectively. Among the non-mosaic Turner Syndrome patients, genotype 1298AA was found in 36.5 percent, genotype 1298AC in 39.4 percent, and genotype 1298CC in 22.1 percent. In the control group, genotypes 1298AA, 1298AC and 1298CC were present at the following frequencies: 52.6 percent, 40.7 percent and 6.7 percent, respectively. CONCLUSION: No correlation was observed between the MTHFR gene polymorphism 677 and chromosomal aneuploidy in the...
INTRODUÇÃO: Disfunções no metabolismo dos folatos podem resultar em hipometilação do DNA e na segregação cromossômica anormal. Dois polimorfismos comuns no gene MTHFR (C677T e A1298C) reduzem a atividade da enzima e, quando associados a estudos de aneuploidias apresentam resultados conflitantes. O objetivo do presente estudo foi a análise dos polimorfismos do gene MTHFR em mulheres portadoras da síndrome de Turner e em indivíduos de grupo-controle, correlacionando os achados ao mecanismo de formação de aneuploidias cromossômicas. MÉTODOS: Foram estudadas 140 portadoras da síndrome de Turner sendo 36 com mosaicismo cromossômico e 104 não-mosaicos, e um grupo-controle composto por 209 mulheres férteis e saudáveis sem história de prole com aneuplodia. Os polimorfismos MTHFR C677T e A1298C foram estudados por RFLP-PCR e os resultados analisados estatisticamente. RESULTADOS: A freqüência dos genótipos MTHFR 677CC, 677CT e 677TT nas pacientes portadoras de síndrome de Turner e mosaicismo cromossômico foi, respectivamente, 58,3 por cento, 38,9 por cento e 2,8 por cento. Das pacientes portadoras de síndrome de Turner não-mosaico, 47,1 por cento apresentaram o genótipo 677CC, 45,2 por cento o genótipo 677CT e 7,7 por cento apresentaram o genótipo 677TT. Nos 209 indivíduos do grupo-controle, os genótipos 677CC, 677CT e 677TT foram encontrados nas seguintes freqüências: 48,3 por cento, 42,1 por cento e 9,6 por cento, respectivamente. Quanto ao polimorfismo A1298C, as portadoras de síndrome de Turner e mosaicismo cromossômico apresentaram os genótipos 1298AA, 1298AC e 1298CC nas seguintes freqüências: 58,3 por cento, 27,8 por cento e 13,9 por cento, respectivamente. Já nas portadoras de Síndrome de Turner não-mosaico, o genótipo 1298AA foi encontrado em 36,5 por cento, o genótipo 1298AC em 39,4 por cento e o genótipo 1298 CC em 22,1 por cento . No grupo-controle, os genótipos 1298AA, 1298AC e 1298CC estavam presentes nas freqüências 52,6 por cento...