Tse Ngong Leung

Plasma DNA tissue mapping by genome-wide methylation sequencing for noninvasive prenatal, cancer, and transplantation assessments

Significance Plasma consists of DNA released from multiple tissues within the body. Using genome-wide bisulfite sequencing of plasma DNA, we obtained a bird’s eye view of the identities and contributions of these tissues to the circulating DNA pool. The tissue contributors and their relative proportions are identified by a bioinformatics deconvolution process that draws reference from DNA methylation signatures representative of each tissue type. We validated this approach in pregnant women, cancer patients, and transplant recipients. This method also allows one to identify the tissue of origin of genomic aberrations observed in plasma DNA. This approach has numerous research and diagnostic applications in prenatal testing, oncology, transplantation monitoring, and other fields. Plasma consists of DNA released from multiple tissues within the body. Using genome-wide bisulfite sequencing of plasma DNA and deconvolution of the sequencing data with reference to methylation profiles of different tissues, we developed a general approach for studying the major tissue contributors to the circulating DNA pool. We tested this method in pregnant women, patients with hepatocellular carcinoma, and subjects following bone marrow and liver transplantation. In most subjects, white blood cells were the predominant contributors to the circulating DNA pool. The placental contributions in the plasma of pregnant women correlated with the proportional contributions as revealed by fetal-specific genetic markers. The graft-derived contributions to the plasma in the transplant recipients correlated with those determined using donor-specific genetic markers. Patients with hepatocellular carcinoma showed elevated plasma DNA contributions from the liver, which correlated with measurements made using tumor-associated copy number aberrations. In hepatocellular carcinoma patients and in pregnant women exhibiting copy number aberrations in plasma, comparison of methylation deconvolution results using genomic regions with different copy number status pinpointed the tissue type responsible for the aberrations. In a pregnant woman diagnosed as having follicular lymphoma during pregnancy, methylation deconvolution indicated a grossly elevated contribution from B cells into the plasma DNA pool and localized B cells as the origin of the copy number aberrations observed in plasma. This method may serve as a powerful tool for assessing a wide range of physiological and pathological conditions based on the identification of perturbed proportional contributions of different tissues into plasma.

Systematic micro-array based identification of placental mRNA in maternal plasma: Towards non-invasive prenatal gene expression profiling

The discovery of fetal DNA in the plasma of pregnant women1 has led to the development of promising approaches for non-invasive prenatal diagnosis.2–6 However, as fetal and maternal DNA species co-exist in maternal plasma, these DNA based diagnostic applications depend largely on the use of genetic markers that would allow the discrimination between fetal and maternal DNA (for example, the Y chromosome of a male fetus), and thus, a particular genetic marker could generally only be used in a proportion of pregnancies. This situation has prompted a quest by many laboratories to develop fetal nucleic acid markers that are independent of sex or polymorphism.nnThe detection of fetal RNA in maternal plasma7 offers new possibilities for non-invasive prenatal investigation. This field has recently taken on new momentum as robust methods for plasma RNA extraction have been developed8 and circulating RNA has been shown to be surprisingly stable,9 possibly through an association with particulate matter.8 Furthermore, recent studies have identified the placenta as a significant source of such circulating fetal RNA.10 Hence, placental expressed mRNA transcripts, such as those coding for human placental lactogen ( hPL ), human chorionic gonadotropin β subunit ( βhCG ),10 and corticotropin releasing hormone ( CRH ),11 have been shown to be detectable in maternal plasma. Quantitative assays have been developed for the measurement of these circulating mRNA transcripts.8 The pregnancy specificity of these mRNA species has been demonstrated by their rapid clearance from maternal plasma after delivery.10,11 Thus, the detection in maternal plasma of mRNA transcripts derived from the plasma offers new avenues for the development of fetal specific nucleic acid markers that are independent of sex and polymorphism for the non-invasive prenatal assessment of all pregnancies.12 The clinical value of such an approach has …

Impact of First Childbirth on Changes in Women’s Preference for Mode of Delivery: Follow-up of a Longitudinal Observational Study

BACKGROUNDnA womans childbirth experience has an influence on her future preferred mode of delivery. This study aimed to identify determinants for women who changed from preferring a planned vaginal birth to an elective cesarean section after their first childbirth.nnnMETHODSnThis prospective longitudinal observational study involved two units that provide obstetric care in Hong Kong. A mail survey was sent to 259 women 6 months after their first childbirth. These women had participated in a longitudinal cohort study that examined their preference for elective cesarean section in the antenatal period of their first pregnancies. Univariate and multivariate analyses were performed to identify determinants for women who changed from preferring vaginal birth to elective cesarean section.nnnRESULTSnTwenty-four percent (23.8%, 95% CI 18.4-29.3) of women changed from preferring vaginal birth to elective cesarean section after their first childbirth. Determinants found to be positively associated with this change included actual delivery by elective cesarean section (OR 106.3, 95% CI 14.7-767.4) intrauterine growth restriction (OR 19.5, 95% CI 1.1-353.6), actual delivery by emergency cesarean section (OR 8.4, 95% CI 3.4-20.6), higher family income (OR 3.2, 95% CI 1.1-8.8), use of epidural analgesia (OR 2.6, 95% CI 1.0-6.8), and higher trait anxiety score (OR 1.1, 95% CI 1.0-1.3). The most important reason for women who changed from preferring vaginal birth to elective cesarean section was fear of vaginal birth (24.4%).nnnCONCLUSIONSnA significant proportion of women changed their preferred mode of delivery after their first childbirth. Apart from reducing the number of cesarean sections in nulliparous women, prompt provision of education to women who had complications and investigations into fear factors during vaginal birth might help in reducing womens wish to change to elective cesarean section.

Guillain-Barré syndrome in pregnancy.

Guillain–Barré syndrome (GBS) complicating pregnancy is a rare event. Reports before the mid‐1980s suggested that GBS in pregnancy carries a high maternal morbidity and mortality. However, it is uncertain whether availability of active treatment such as plasmapheresis and intravenous immunoglobulin together with advancement in intensive care has improved maternal outcome. This review examines the maternal and fetal outcomes of GBS complicating pregnancy reported in the recent English literature.

Sleep disturbances in Chinese pregnant women

In a prospective study of 247 pregnant Chinese women, the prevalence of sleep disturbances across pregnancy has been assessed using a set of validated questionnaires including the Sleep and Health Questionnaire (SHQ) and the Epworth Sleepiness Scale (ESS). The frequency of self‐reported snoring increased from 29.7% in the first trimester to 40.5% and 46.2% in the second and third trimesters, respectively, with an increase in the prevalence of moderate or severe snoring from 1% in the first trimester to 7.2% in the third trimester (P < 0.01). There was a higher frequency of moderate to severe snoring intensity among subjects with BMI ≥25 compared with those with BMI <25 kg/m2 in the third trimester (20.8%vs 5.3%, P < 0.01). Subjective sleepiness, as determined by the ESS, increased significantly from 8.6 to 9.4 and 9.6 in the first, second and third trimesters, respectively.

Prenatal treatment of chorioangioma by microcoil embolisation

A 39 year old parous woman had a huge chorioangioma complicated by fetal anaemia. Her past obstetric history was unremarkable, with three normal vaginal deliveries at term. In her current pregnancy when she was first seen at 24 weeks of gestation, her fundal height was 28 cm. An ultrasound scan showed a placental tumour measuring 10 cm in diameter protruding into the amniotic cavity. The placenta was anterior. The tumour was predominantly solid with multiple echo-free spaces. Colour Doppler examination revealed a vascular tumour, with a large feeding vessel measured 7.4 mm in diameter supplying the tumour. The feeding vessel bifurcated soon after its entry into the tumour (Fig. 1). Fetal measurements were on the third centile, and there was cardiomegaly with a cardiothoracic ratio of 0.62 (Fig. 2). The fetal morphology was otherwise normal. The liquor volume was also diminished, with only one identifiable pocket of 3.7 cm in diameter. A diagnosis of chorioangioma with possible fetal anaemia was made. Cordocentesis was performed and confirmed fetal anaemia (haemoglobin concentration: 5.7 g/dL). Intrauterine transfusion was performed with 50 ml of irradiated Rhesus-positive maternal packed cells (haematocrit of 80%), and the haemoglobin level increased to 9.6 g/dL. The fetal karyotype was normal. To prevent the recurrence of fetal anaemia due to chronic sequestration of fetal blood through the tumour, other treatment was considered to be necessary. Ultrasoundguided transcutaneous embolisation of the chorioangioma was performed two days later under local anaesthesia. Eight pieces of microcoil, including two 2-mm/3-mm coils, two 2-mm/5-mm coils and one 2-mm/6-mm coil, were inserted into the main and intratumoural branches and at the bifurcation of the main trunk of the feeding artery through a 15-cm-long, 20-gauge spinal needle. A significant reduction of blood flow was observed (Fig. 3) but the procedure was abandoned because of increasing discomfort felt by the woman due to prolonged sustained supine posture. The procedure lasted 45 minutes. Intrauterine transfusion and embolisation were repeated under general anaesthesia one week later because of persistent cardiomegaly and fetal anaemia. The fetal haemoglobin increased to 12.8 g/dL after transfusion of 60 ml of irradiated maternal packed cells. The blood flow to the tumour was diminished after nine pieces of microcoil were inserted. Although the blood flow into the tumour was significant reduced, cardiomegaly and fetal anaemia persisted. Further attempts at embolisation were therefore considered not to be justified. The fetal haemoglobin level decreased approximately 6 gm/dL every week, and repeated intrauterine transfusions were required at 27, 28 and 29 weeks of gestation. The size of the chorioangioma slowly increased to 18 cm in diameter over this time. The woman went into spontaneous labour at 29 weeks and 6 days. An emergency classical caesarean section was performed for fetal malpresentation. The baby weighed 1.185 kg, with an umbilical arterial pH of 7.161. The baby died on the second day of life because of prematurity, heart failure and disseminated intravascular coagulopathy. The placenta with the tumour weighed 2.75 kg. The tumoural mass measured 20 18 17 cm. There was extensive infarction involving over 60% of the tumour volume. Microcoils and thrombus formation were identified within the feeding artery and its branches (Fig. 4). Microscopic examination showed that the chorioangioma was composed of predominantly capillary-sized vascular channels in the fibromyxoid matrix and confirmed the presence of thrombosis of the feeding arteries and infarctions.

Higher Median Levels of Free β-hCG and PAPP-A in the First Trimester of Pregnancy in a Chinese Ethnic Group

Objective: To study the effect of ethnic Chinese on the medians of free β-hCG and PAPP-A in the first trimester of pregnancy. Methods: The data of 943 women undergoing first trimester combined screening for fetal Down syndrome were analysed to derive the Chinese-specific medians. The calculated risk of Down syndrome based on these Chinese-specific medians was compared with that based on the original algorithm of the Fetal Medicine Foundation (FMF). Results: The maternal serum levels of multiples of median of free β-hCG and PAPP-A were significantly higher among the Chinese than among the Caucasians. The weight-adjusted gestation-specific medians were developed. Without adjustment for ethnicity, the original FMF algorithm underestimated the risk of Down syndrome by a median of 1%. Adjustment by ethnicity increased the false-positive rate by 10% (from 5.3 to 5.9%). Conclusion: Ethnic Chinese have a significantly higher maternal serum level of free β-hCG and PAPP-A in the first trimester, which could not be explained by differences in maternal weight. Adjustment for ethnicity may be necessary for these biochemical markers in a first trimester screening program.

First trimester combined screening for Trisomy 21 in Hong Kong: outcome of the first 10,000 cases

Objective.u2003To examine the effectiveness of first trimester fetal Trisomy 21 (T21) screening using a combination of maternal age, nuchal translucency, maternal serum levels of free β-hCG and PAPP-A in a predominantly Chinese population in Hong Kong. Methods.u2003Consecutive women who underwent the combined screening for T21 between 11 and 13 + 6 weeks of gestation between 2003 and 2007 were recruited. Risk of T21 was calculated using Fetal Medicine Foundation algorithm and karyotyping was advised when the risk was 1:300 or above. All women were followed up for pregnancy and fetal outcome. Results.u200310,363 fetuses underwent screening. 99% of the women were Chinese and 27.4% were at or above 35 years old. 618 fetuses were screened positive (5.9%), which included 31 cases of T21, 14 cases of T18, 7 cases of T13, 10 cases of 45XO and 7 cases of other chromosomal abnormalities. Among the 9745 screened negative fetuses all but 50 (0.5%) had a known outcome, which included three T21 and four other chromosomal abnormalities. All were subsequently identified at the morphology scan except for one case of T21. The detection rate and false positive rates for T21 were 91.2% and 5.4%, respectively and the positive predictive value for all chromosomal abnormalities was 1 in 9. Conclusions.u2003Combined screening for T21 is highly effective among Chinese women. Training, quality control, regular auditing and follow up are essential to maintain screening standards.

A case-controlled study comparing clinical course and outcomes of pregnant and non-pregnant women with severe acute respiratory syndrome.

Objectiveu2003 To compare the clinical courses and outcomes of pregnant severe acute respiratory syndrome (SARS) patients and non‐pregnant SARS patients.

Influences of perinatal factors on cord blood thyroid‐stimulating hormone level

Background. Cord blood thyroid‐stimulating hormone level is affected by various perinatal factors. The aim of this study is to investigate the relative impact of these factors on the cord blood thyroid‐stimulating hormone results in singleton pregnancies.