Effect of non-invasive prenatal testing as a contingent approach on the indications for invasive prenatal diagnosis and prenatal detection rate of Down's syndrome.

INTRODUCTION: In Hong Kong, universal combined first-trimester screening for Down's syndrome was started as a 'free service' in July 2010. Non-invasive prenatal testing was available as a self-financed item in August 2011. This study aimed to determine whether the introduction of non-invasive prenatal testing as a contingent approach influenced the indications for invasive prenatal diagnosis and the consequent prenatal detection of Down's syndrome. METHODS: This historical cohort study was conducted at the Prenatal Diagnosis Clinic of Queen Elizabeth Hospital in Hong Kong. We compared the indications for invasive prenatal diagnosis and prenatal detection of Down's syndrome in singleton pregnancies 1 year before and 2 years following the availability of non-invasive prenatal testing as a contingent test after a positive aneuploidy test. All pregnant women who attended our hospital for counselling about universal Down's syndrome screening between August 2010 and July 2013 were recruited. RESULTS: A total of 16 098 women were counselled. After the introduction of non-invasive prenatal testing, the invasive prenatal diagnosis rate for a positive aneuploidy screening reduced from 77.7% in 2010-11 to 68.8% in 2012-13. The new combined conventional plus non-invasive prenatal testing strategy was associated with a lower false-positive rate (6.9% in 2010-11 vs 5.2% in 2011-12 and 4.9% in 2012-13). There was no significant increase in invasive prenatal diagnosis for structural anomalies over the years. There was no significant trend in the overall prenatal detection rate of Down's syndrome (100% 1 year before vs 89.1% 2 years after introduction of non-invasive prenatal testing). Four (2.6%) of 156 women who underwent non-invasive prenatal testing for a screen-positive result had a high-risk result for trisomy 21, which was subsequently confirmed by invasive prenatal diagnosis. There were no false-negative cases. CONCLUSION: The introduction of non-invasive prenatal testing as a contingent approach reduced the invasive prenatal diagnosis rate for a positive aneuploidy screening without affecting the invasive prenatal diagnosis rate for structural anomalies or the overall detection rate of fetal Down's syndrome.

Functional polymorphisms in the BRCA1 promoter influence transcription and are associated with decreased risk for breast cancer in Chinese women.

BACKGROUND: The BRCA1 gene is an important breast-cancer susceptibility gene. Promoter polymorphisms can alter the binding affinity of transcription factors, changing transcriptional activity and may affect susceptibility to disease. METHODS AND RESULTS: Using direct sequencing of the BRCA1 promoter region, we identified four polymorphisms c.-2804T-->C (rs799908:T-->C), c.-2265C-->T (rs11655505:C-->T), c.-2004A-->G (rs799906:A-->G) and c.-1896(ACA)(1)-->(ACA)(2) (rs8176071:(ACA)(1)-->(ACA)(2)) present in Hong Kong Chinese. Each polymorphism was studied independently and in combination by functional assays. Although all four variants significantly altered promoter activity, the c.-2265T allele had stronger binding than the C allele, and the most common mutant haplotype, which contains the c.-2265T allele, increased promoter activity by 70%. Risk association first tested in Hong Kong Chinese women with breast cancer and age-matched controls and replicated in a large population-based study of Shanghai Chinese, together totalling >3000 participants, showed that carriers of the c.-2265T allele had a reduced risk for breast cancer (combined odd ratio (OR) = 0.80, 95% CI 0.69 to 0.93; p = 0.003) which was more evident among women aged >or=45 years at first diagnosis of breast cancer and without a family history of breast cancer (combined OR = 0.75, 95% CI 0.61 to 0.91; p = 0.004). The most common haplotype containing the c.-2265T allele also showed significant risk association for women aged >or=45 years without a family history of breast cancer (OR = 0.64, 95% CI 0.46 to 0.89; p = 0.008). CONCLUSION: This comprehensive study of BRCA1 promoter polymorphisms found four variants that altered promoter activity and with the most significant contribution from c.-2265C-->T, which could affect susceptibility to breast cancer in the Chinese population. Its significance in other populations remains to be investigated.

Oct4 is epigenetically regulated by methylation in normal placenta and gestational trophoblastic disease.

Oct4 is a transcription factor that plays a crucial role in maintaining pluripotency of embryonic stem cells. Down-regulation of Oct4 is associated with the differentiation of trophectoderm cell lineage, from which the normal placenta derives. We investigated the methylation and expression status of Oct4 in normal placenta and gestational trophoblastic disease (GTD) as attempts to investigate the role of Oct4 in the pathogenesis of GTD. By methylation-specific PCR, we observed both methylated and unmethylated Oct4 alleles in all 25 first trimester and 10 term placentas while 33% (18/54) of hydatidiform moles, and two choriocarcinoma cell line (JEG3 and JAR), only displayed methylated Oct4 allele. By quantitative TaqMan real-time PCR, Oct4 mRNA was significantly reduced in hydatidiform moles (P=0.04), JEG3 and JAR (P=0.024) when compared with normal placentas. Oct4 methylation was significantly correlated with Oct4 mRNA expression in placenta and GTD (P=0.012). Hypermethylation in minimal promoter and exon 1 region of Oct4 were confirmed in JEG3 and JAR by bisulfite genomic sequencing. The Oct4 mRNA expression in JEG3 and JAR increased after treatment with 5-aza-2'-deoxycytidine and/or trichostatin A. Our findings suggest that Oct4 is down-regulated by hypermethylation in normal placenta and GTD and such process is important in pathogenesis of GTD.