RESUMO
PURPOSE: To prospectively validate a protocol for noninvasive fetal sex determination in maternal plasma and demonstrate its applicability to clinical practice. METHODS: Peripheral blood from 404 pregnant women undergoing prenatal invasive testing was collected from 6 to 23 weeks of gestation. Real-time PCR was performed for the SRY gene and multicopy DYS14 marker sequence located within the TSPY gene by the TaqMan minor groove binder probe assay as a first-line test. Owing to a false-positive result, amplification of repetitive motifs of the DAZ gene region was also tested as a second-line test performed in the last 232 patients enrolled in our series. A diagnostic algorithm was designed using a combination of these three markers. Fetal gender determined by noninvasive prenatal diagnosis (NIPD) was compared with that diagnosed by quantitative fluorescent PCR after invasive testing or ultrasound. RESULTS: A single false-positive result was obtained in the first 172 pregnancies. Reporting criteria were modified in the subsequent 232 pregnancies, giving an overall sensitivity and specificity of 100% (95% CI 99.8-100%) and 99.5% (95% CI 98.1-100%), respectively. Pregnancy outcome was obtained in all cases, including 221 male-bearing and 183 female-bearing pregnancies. CONCLUSION: NIPD for fetal sex determination in maternal plasma is highly accurate and clinically applicable if robust reporting criteria are applied.
Assuntos
Testes Genéticos/métodos , Diagnóstico Pré-Natal/métodos , Análise para Determinação do Sexo/métodos , DNA/sangue , Proteína 1 Suprimida em Azoospermia , Distrofina/genética , Estudos de Viabilidade , Feminino , Feto , Doenças Genéticas Ligadas ao Cromossomo X/diagnóstico , Doenças Genéticas Ligadas ao Cromossomo X/genética , Humanos , Masculino , Gravidez , Estudos Prospectivos , Proteínas de Ligação a RNA/genética , Reação em Cadeia da Polimerase em Tempo Real , Sensibilidade e Especificidade , Proteína da Região Y Determinante do Sexo/genéticaRESUMO
OBJECTIVE: The aim of this study was to determine if the use of different mappers for NIPT may vary the results considerably. METHODS: Peripheral blood was collected from 217 pregnant women, 58 pathological (34 pregnancies with trisomy 21, 18 with trisomy 18, and 6 with trisomy 13) and 159 euploid. MPS was performed following a manufacturer's modified protocol of semiconductor sequencing. Obtained reads were mapped with two different software programs: TMAP and HPG-Aligner, comparing the results. RESULTS: Using TMAP, 57 pathological samples were correctly detected (sensitivity 98.28%, specificity 93.08%): 33 samples as trisomy 21 (sensitivity 97.06%, specificity 99.45%), 16 as trisomy 18 (sensibility 88.89%, specificity 93.97%), and 6 as trisomy 13 (sensibility 100%, specificity 100%). 11 false positives, 1 false negative, and 2 samples incorrectly identified were obtained. Using HPG-Aligner, all the 58 pathological samples were correctly identified (sensibility 100%, specificity 96.86%): 34 as trisomy 21 (sensibility 100%, specificity 98.91%), 18 as trisomy 18 (sensibility 100%, specificity 98.99%), and 6 as trisomy 13 (sensibility 100%, specificity 99.53%). 5 false positives were obtained. CONCLUSION: Different mappers use slightly different algorithms, so the use of one mapper or another with the same batch file can provide different results.