Prenatal Exome Sequencing Analysis in Fetuses with Various Ultrasound Findings.

OBJECTIVES: To evaluate the use of Exome Sequencing (ES) for the detection of genome-wide Copy Number Variants (CNVs) and the frequency of SNVs-InDels in selected genes related to developmental disorders in a cohort of consecutive pregnancies undergoing invasive diagnostic procedures for minor or simple ultrasound findings with no indication of ES. METHODS: Women undergoing invasive diagnostic testing (chorionic villus sampling or amniocentesis) for QF-PCR and chromosomal microarray analysis (CMA) due to prenatal ultrasound findings without an indication for ES were selected over a five-month period (May-September 2021). ES was performed to compare the efficiency of genome-wide CNV detection against CMA analysis and to detect monogenic disorders. Virtual gene panels were selected to target genes related to ultrasound findings and bioinformatic analysis was performed, prioritizing variants based on the corresponding HPO terms. The broad Fetal Gene panel for developmental disorders developed by the PAGE group was also included in the analysis. RESULTS: A total of 59 out of 61 women consented to participate in this study. There were 36 isolated major fetal anomalies, 11 aneuploidy markers, 6 minor fetal anomalies, 4 multiple anomalies, and 2 other ultrasound signs. Following QF-PCR analysis, two uncultured samples were excluded from this study, and six (10%) common chromosome aneuploidies were detected. In the remaining 51 cases, no pathogenic CNVs were detected at CMA, nor were any pathogenic variants observed in gene panels only targeting the ultrasound indications. Two (3.9%) monogenic diseases, apparently unrelated to the fetal phenotype, were detected: blepharo-cheilo-odontic syndrome (spina bifida) and Duchenne muscular dystrophy (pyelocaliceal dilation). CONCLUSIONS: In our series of pregnancies with ultrasound findings, common aneuploidies were the only chromosomal abnormalities present, which were detected in 10% of cases. ES CNV analysis was concordant with CMA results in all cases. No additional findings were provided by only targeting selected genes based on ultrasound findings. Broadening the analysis to a larger number of genes involved in fetal developmental disorders revealed monogenic diseases in 3.9% of cases, which, although apparently not directly related to the indications, were clinically relevant.

Recomendaciones para la aplicación clínica de la detección de aneuploidías en ADN fetal libre en sangre materna / Recommendations for the clinical application of aneuploidy detection in cell-free fetal DNA in maternal blood

No disponible

Recomendaciones para el uso clínico del microarray genómico en diagnóstico prenatal / Recommendations for the clinical use of genomic microarray in prenatal diagnosis

No disponible

Cribado prenatal no invasivo de aneuploidías mediante análisis de ADN fetal en sangre materna / Non-invasive prenatal screening for aneuploidy through analysis of cell-free fetal DNA from maternal blood

El objetivo de este trabajo es analizar la sensibilidad y la especificidad en gestaciones únicas del análisis de cell free DNA (cfDNA) en sangre materna para el diagnóstico de las principales trisomías fetales (t21,t18 y t13), así como comparar los resultados con los obtenidos mediante el cribado combinado bioquímico ecográfico (CC); 582 gestaciones de más de 10 semanas fueron estudiadas. Todos los resultados con alto riesgo fueron confirmados mediante determinación prenatal del cariotipo o tras el nacimiento. Se realizó seguimiento posnatal en todos los casos, excepto en 5 gestaciones en las que no pudo ser confirmado el cariotipo por pérdida fetal tardía o aborto y renuncia de los padres a su estudio. El análisis de cfDNA fue posible tras la primera determinación en 97.1% de las muestras. En 3 (0,5%) no se obtuvo resultado tras 2 o incluso 3 extracciones; 14 fetos presentaron alto riesgo de t21 en sangre materna que fue confirmado en todos los casos; 3 fetos con alto riesgo de t18 en el estudio no invasivo fueron también confirmados tras el estudio del cariotipo fetal. No hubo falsos positivos ni negativos en la muestra analizada. La sensibilidad del CC fue del 87,5% para una tasa del 6,7% de falsos positivos. El análisis de cfDNA en sangre materna permite con alta sensibilidad y especificidad establecer el riesgo de las principales trisomías fetales. Los resultados obtenidos son probablemente superiores a los del CC. El número de procedimientos invasivos en la población de estudio se redujo de forma muy significativa (AU)

The aim of this study was to assess the sensitivity and specificity of cell-free (cfDNA) screening for diagnosis of the main fetal trisomies (t21,t18 y t13) and to compare its efficiency with that of first-trimester combined screening (FTS). A total of 582 samples were analyzed from singleton pregnancies above 10 weeks of gestation. All abnormal results were confirmed either with a prenatal invasive procedure or by neonatal karyotyping. Postnatal follow-up was also carried out in all but 5 low-risk pregnancies in which the karyotype could not be confirmed due to late fetal loss or miscarriage or parental refusal. cfDNA determination provided a risk score at the first attempt in 97.1% of the samples. Only 3 cases failed after 2 or 3 redraws (0.5%). High-risk results were provided by the Harmony test in 14 cases for t21 and in 3 for t18. No false positive results were observed. No false negative results were obtained in any of the 557 cases with a result of low-risk and postnatal follow-up. The sensitivity of FTS was 87.5%, with a false positive rate of 6.7%. cfDNA analysis in maternal blood has high sensitivity and specificity in establishing the risk of the main fetal trisomies. The results are probably superior to those obtained with FTS. The number of invasive procedures in the study population was significantly reduced (AU)

Reacción en cadena de la polimerasa cuantitativa y cultivo largo: ¿el mejor método para el estudio citogenético de muestras de vellosidad corial? / Quantitative Polymerase Chain Reaction and long term culture: the best method for cytogenetic study of chorionic villus sampling?

El diagnóstico prenatal citogenético durante el primer trimestre de gestación se realiza a partir de biopsias de vellosidad corial. Para la obtención de metafases se utilizan dos métodos: el cultivo corto o semidirecto (STC) y cultivo largo (LTC). La principal ventaja del STC es que no presenta contaminación materna y la del LTC es que no hay descritos en la literatura falsos negativos. Se considera que la combinación de las dos técnicas (STC y LTC) es la estrategia diagnóstica más eficaz para este tipo de estudios. La técnica de PCR cuantitativa fluorescente (QF-PCR) permite evaluar las aneuploidías más frecuentemente implicadas en el diagnóstico prenatal en 24-48 horas en muestras de vellosidad corial. El objetivo de este trabajo es evaluar la combinación de QF-PCR y LTC como sustituto de las clásicas STC y LTC para el diagnóstico prenatal en muestras de vellosidad corial. Para ello presentamos nuestra experiencia en 900 muestras de vellosidad corial(AU)

First trimester cytogenetic prenatal diagnosis is performed on chorionic villus biopsies. Two methods are used to obtain metaphases: the short-term or semi-direct culture (STC) and long term culture (LTC). The main advantage of STC is that there is no risk of maternal contamination, and of LTC that no false-negative findings are described in the literature. It is considered that the combination of the two techniques (STC and LTC) is the most effective diagnostic strategy for this type of study. The technique of quantitative fluorescent PCR (QF-PCR) allows the evaluation of aneuploidy most frequently involved in prenatal diagnosis in 24-48 hours in chorionic villus samples. The aim of this study is to evaluate the combination of QF-PCR and LTC as a substitute for classical STC and LTC for prenatal diagnosis in chorionic villus samples. We present our experience in 900 chorionic villus samples(AU)