Immediate postpartum cessation of tenofovir did not increase risk of virological or clinical relapse in highly viremic pregnant mothers with chronic hepatitis B infection.

Background & Aims: Peripartum prophylaxis (PP) with tenofovir disoproxil fumarate (TDF) is the standard of care to prevent mother-to-child transmission of chronic hepatitis B (CHB) infection in mothers who are highly viremic. We investigated the maternal and infant outcomes in a large Chinese cohort of TDF-treated CHB pregnant participants. Methods: In this prospective study, treatment-naive mothers with CHB and highly viremic (HBV DNA ≥200,000 IU/ml) but without cirrhosis were treated with TDF at 24-28 weeks of pregnancy. In accordance with Chinese CHB guidelines, TDF was stopped at delivery or ≥4 weeks postpartum. Serum HBV DNA and alanine aminotransferase were monitored every 6-8 weeks to determine virological relapse (VR). Infants received standard neonatal immunization, and HBV serology was checked at 7-12 months of age. Results: Among 330 participants recruited (median age 30, 82.7% HBeAg+, median HBV DNA 7.82 log IU/ml), TDF was stopped at delivery in 66.4% and at ≥4 weeks in 33.6%. VR was observed in 98.3%, among which 11.6% were retreated with TDF. Timing of TDF cessation did not alter the risk of VR (99.0 vs. 96.9%), clinical relapse (19.5 vs. 14.3%), or retreatment (12.6 vs. 10.1%) (all p > 0.05). A similar proportion of patients developed alanine aminotransferase flare five times (1.1 vs. 2.1%; p = 0.464) and 10 times (0.5 vs. 0%; p = 0.669) above the upper limit of normal (ULN) in the early withdrawal and late withdrawal groups, respectively. No infants developed HBsAg-positivity. Conclusions: PP-TDF and neonatal immunization were highly effective in preventing mother-to-child transmission of HBV in mothers who are highly viremic. Timing of cessation of PP-TDF did not affect the risk of VR or retreatment. Impact and Implications: In pregnant mothers with chronic hepatitis B infection who are started on peripartum tenofovir to prevent mother-to-child-transmission (MTCT), the optimal timing for antiviral withdrawal during the postpartum period remains unknown. This prospective study demonstrates that stopping tenofovir immediately at delivery, compared with longer treatment duration of tenofovir, did not lead to an increased risk of virological relapse, retreatment, or transmission of the virus to the baby. Shortening the duration of peripartum antiviral prophylaxis from 12 weeks to immediately after delivery can be considered. The immediate withdrawal of peripartum tenofovir, combined with standard neonatal immunization schemes, is 100% effective in preventing MTCT among pregnant mothers with CHB who are highly viremic, with a high rate of vaccine response in infants.

20 years review of antenatal diagnosis of haemoglobin Bart's disease and treatment with intrauterine transfusion.

OBJECTIVE: To review prenatal diagnosis and outcome of alpha thalassaemia major through universal antenatal screening. METHOD: This was a retrospective study on ultrasound features, antenatal diagnosis, in-utero intervention and long term outcome of pregnancies at risk of Haemoglobin Bart's hydrops foetalis syndrome attending prenatal diagnosis from 2000 to 2019 at Tsan Yuk Hospital in Hong Kong. RESULTS: Among 390 foetuses from 373 at-risk pregnancies, 122 (31%) prenatal invasive procedures were performed and 65 affected foetuses were diagnosed antenatally. For foetuses with ultrasound features of anaemia, the diagnostic yield of BHFS was 73%. Cardiomegaly carried a positive predictive value of 65.2% while its absence had the highest negative predictive value (96.0%). Three women having affected foetuses continued pregnancy and received intrauterine transfusion beginning 20 weeks of gestation. All babies were born alive and non-hydropic. They were managed with regular transfusion and cured by haematopoietic stem cell transplantation. CONCLUSIONS: Absence of ultrasound features of anaemia had high negative predictive value for alpha thalassaemia major. Couple at risk of having affected foetus could be offered serial ultrasound surveillance. Invasive testing for pregnancies with features of foetal anaemia provided high diagnostic yield. Intrauterine transfusion corrected foetal anaemia and allowed long term transfusion free survival without significant neurological sequelae following postnatal transplant therapy.

Prenatal diagnosis of 5p deletion syndrome: Report of five cases.

It is difficult to prenatally identify 5p deletion (-) syndrome. Here, we report five cases of 5p- syndrome diagnosed by invasive prenatal diagnosis. Of them, three had a small cerebellum in the second trimester. In one case, a prominent renal pelvis and an absent nasal bone were also found in the first trimester. However, there were no abnormal ultrasound findings in the other two cases. Two cases had noninvasive prenatal testing and one showed a '5p- syndrome positive result' because of reduced amount of cell-free DNA in 5p. Two had combined first-trimester screening performed where one had a high-risk result for trisomy 18 and a low pregnancy-associated plasma protein-A level. Two cases of 5p- syndrome resulted from a parental balanced translocation. Prenatal diagnosis will only be made on invasive prenatal diagnosis for abnormal ultrasound findings with small cerebellum, abnormal prenatal screening or a parental reciprocal translocation involving 5p.

Experience of chromosomal microarray applied in prenatal and postnatal settings in Hong Kong.

Chromosomal microarray (CMA) is recommended as a first tier investigation for patients with developmental delay (DD), intellectual disability (ID), autistic spectrum disorder (ASD), and multiple congenital anomalies (MCA). It is widely used in the prenatal and postnatal settings for detection of chromosomal aberrations. This is a retrospective review of all array comparative genomic hybridization (aCGH/ array CGH) findings ascertained in two major prenatal and postnatal genetic diagnostic centers in Hong Kong from June 2012 to December 2017. Medical records were reviewed for cases with pathogenic and variants of uncertain clinical significance (VUS). Classification of copy number variants (CNVs) was based on current knowledge and experience by August 2018. The aims of this review are to study the diagnostic yield of array CGH application in prenatal and postnatal settings in Hong Kong and to describe the spectrum of abnormalities found. Prenatal indications included abnormal ultrasound findings, positive Down syndrome screening, abnormal noninvasive prenatal test results, advanced maternal age and family history of chromosomal or genetic abnormalities. Postnatal indications included unexplained DD, ID, ASD, and MCA. A total of 1,261 prenatal subjects and 3,096 postnatal patients were reviewed. The prenatal diagnostic yield of pathogenic CNV and VUS (excluding those detectable by karyotype) was 3.5%. The postnatal diagnostic yield of pathogenic CNV was 15.2%. The detection rates for well-defined microdeletion and microduplication syndromes were 4.6% in prenatal and 6.1% (1 in 16 index patients) in postnatal cases, respectively. Chromosomes 15, 16, and 22 accounted for over 21 and 25% of pathogenic CNVs detected in prenatal and postnatal cohorts, respectively. This review provides the first large scale overview of genomic imbalance of mostly Chinese patients in prenatal and postnatal settings.

Knowledge, attitude and ethical consideration of Chinese couples requesting preimplantation genetic testing in Hong Kong.

AIM: Increasing preimplantation genetic testing (PGT) cycles are being performed in Hong Kong. This study aims to evaluate the knowledge, attitude and ethical consideration of Chinese couples toward PGT. METHODS: Couples requesting PGT between June 2013 and March 2014 were invited to complete a questionnaire. RESULTS: Total 49 couples (49 women, 47 men) completed the questionnaires. Eighteen couples (37%) were waiting for PGT (pre-PGT group), 15 couples (31%) were undergoing PGT (PGT group) and 16 couples (32%) had completed at least one PGT cycle (post-PGT group). Only 53% of the couples could tell the recurrent risk, and 31% (with monogenic disorders) could tell the mode of inheritance of their condition. The acceptability of PGT (>80%) and attitude toward the embryo fate (58-78%) were good. The post-PGT group had more concern than the PGT and pre-PGT groups on the prenatal diagnostic testing (**P = 0.007). 12.5% of the couples worried about the transfer of healthy embryos with carrier state and they all had monogenic disorders. If the prenatal testing confirmed an affected fetus, a higher percentage (32%) in the Post-PGT group disagreed to terminate the pregnancy in contrast to a much lower 6% in the pre-PGT group (**P = 0.02). Three-quarter of the couples opted to tell their child about their conception through PGT. CONCLUSION: Chinese couples in Hong Kong had an overall good acceptability and positive attitude toward PGT. We appreciate the difficulties the couples have gone through PGT. A checklist on what to cover pre-during-post-PGT in the counseling process is needed.

Identifying the genetic causes for prenatally diagnosed structural congenital anomalies (SCAs) by whole-exome sequencing (WES).

BACKGROUND: Whole-exome sequencing (WES) has become an invaluable tool for genetic diagnosis in paediatrics. However, it has not been widely adopted in the prenatal setting. This study evaluated the use of WES in prenatal genetic diagnosis in fetuses with structural congenital anomalies (SCAs) detected on prenatal ultrasound. METHOD: Thirty-three families with fetal SCAs on prenatal ultrasonography and normal chromosomal microarray results were recruited. Genomic DNA was extracted from various fetal samples including amniotic fluid, chorionic villi, and placental tissue. Parental DNA was extracted from peripheral blood when available. We used WES to sequence the coding regions of parental-fetal trios and to identify the causal variants based on the ultrasonographic features of the fetus. RESULTS: Pathogenic mutations were identified in three families (n = 3/33, 9.1%), including mutations in DNAH11, RAF1 and CHD7, which were associated with primary ciliary dyskinesia, Noonan syndrome, and CHARGE syndrome, respectively. In addition, variants of unknown significance (VUSs) were detected in six families (18.2%), in which genetic changes only partly explained prenatal features. CONCLUSION: WES identified pathogenic mutations in 9.1% of fetuses with SCAs and normal chromosomal microarray results. Databases for fetal genotype-phenotype correlations and standardized guidelines for variant interpretation in prenatal diagnosis need to be established to facilitate the use of WES for routine testing in prenatal diagnosis.

First Report of a Novel Deletion Due to εγδß-Thalassemia in a Chinese Family.

A fetus of Chinese descent presented with ultrasound features of anemia at 20 weeks' gestation. Father had low a mean corpuscular volume (MCV) level. Multiplex gap-polymerase chain reaction (gap-PCR) excluded common α-thalassemia (α-thal) deletions and mutations and PCR sequencing of the α1- and α2-globin genes were negative. The fetus had a normal karyotype. Array comparative genomic hybridization (aCGH) showed a single copy loss of 189.87 kb in chromosome 11p15.4, involving the whole ß-globin gene cluster, inherited from the father. Multiplex ligation-dependent probe amplification (MLPA) confirmed the deletion included the ε-globin gene, confirming the diagnosis of heterozygous (εγδß)0-thalassemia [(εγδß)0-thal], also inherited from the father. The fetus had a worsening anemic condition in utero and required a transfusion at 26 weeks' gestation, raising the hemoglobin (Hb) level from 5.3 to 12.6g/dL. A cesarean-section was subsequently performed at 32 weeks' gestation because of reduced fetal movements, and a 1650g baby girl with good Apgar scores was delivered. Hemoglobin at birth was 12.8g/dL, gradually dropping to 6.8 g/dL, requiring three neonatal transfusions. Her condition gradually stabilized after 2 months with Hb stable at 8.0 g/dL. Family screening by MLPA showed that the paternal grandmother carried the same deletion. The deletion in this case is distinct and is the reported first case. The deletion transmitted across three successive generations with great phenotypic variation. The final adult phenotype of (εγδß)0-thal is usually mild, therefore, with accurate prenatal diagnosis this condition is salvageable by in utero and early neonatal transfusions, preventing adverse pregnancy and neonatal outcomes.

A Fetus with Hb Bart's Disease Due to Maternal Uniparental Disomy for Chromosome 16.

We here report an unusual case of Hb Bart's (γ4) disease. Thalassemia screening of a couple showed that the wife was an α(0)-thalassemia (α(0)-thal) carrier and her husband's mean corpuscular volume (MCV) was normal. Chorionic villus sampling (CVS) was performed at 13 weeks' gestation for positive Down syndrome screening and chromosomal study of the cultured CVS showed a normal karyotype. Ultrasound examination at 22 weeks' gestation showed fetal cardiomegaly and raised middle cerebral artery peak systolic velocity. Cordocentesis confirmed fetal anemia and showed Hb Bart's disease. Multiplex gap-polymerase chain reaction (gap-PCR) for α-thal deletions on DNA extracted from the CVS showed the presence of a homozygous α(0)-thal - -(SEA) (Southeast Asian) deletion. The husband was found to be a carrier of the α(+)-thal -α(3.7) (rightward) deletion. Non paternity was excluded by fluorescent PCR using short tandem repeat (STR) markers on chromosomes 13, 18 and 21. A de novo terminal deletion of chromosome 16 was excluded by array comparative genomic hybridization (aCGH). Detection of uniparental disomy (UPD), using STR markers on chromosome 16 showed maternal uniparental isodisomy from 16pter to 16p13.2, and uniparental heterodisomy from 16p13.13 to 16qter.

An Unusual Hydrops Fetalis Associated with Compound Heterozygosity for Krüppel-like Factor 1 mutations.

Hydrops fetalis is commonly due to Hb Bart's (γ4) disease in South East Asia. Here, we report an unusual case of hydrops fetalis due to congenital dyserythropoietic anemia (CDA) associated with compound heterozygosity for Krüppel-like factor 1 (KLF1) gene mutations. Fetal cardiomegaly was first detected on routine mid-trimester scan in a pregnant woman with normal mean corpuscular volume (MCV) and Rhesus positive status. The fetus subsequently developed hydrops fetalis, and cordocentesis showed severe fetal anemia with a hemoglobin (Hb) level of 3.4 g/dL. Common causes of fetal anemia including Hb Bart's disease, parvovirus infection, and red cell antibodies were excluded. In view of the marked increase in erythroblasts at various stages of erythropoiesis, the diagnosis of CDA was suspected. We screened the couple for previously reported KLF1 gene mutations, showing that the mother was heterozygous for the c.525_526insCGGCGCC, p.Gly176Argfs*179 mutation, and her husband heterozygous for c.1012C>A, p.Pro338Thr mutation. The fetus was a compound heterozygote for these two KLF1 mutations. After counseling, repeated intrauterine transfusions were given at 27, 29, and 34 weeks' gestation; the hydrops fetalis was resolved. The baby was delivered at 34 weeks' gestation and required monthly blood transfusions but was otherwise thriving. Bone marrow aspiration at 10 months of age showed the features of ineffective erythropoiesis, compatible with CDA. In conclusion, hydrops fetalis can rarely be due to CDA associated with a compound heterozygous mutation for KLF1 gene mutations, and be managed by repeated intrauterine transfusions. Our present report adds to the wide clinical spectrum of KLF1 mutations.

Spread of X inactivation on chromosome 15 is associated with a more severe phenotype in a girl with an unbalanced t(X; 15) translocation.

We report on a baby girl with multiple congenital abnormalities, including cleft palate, intrauterine growth restriction, and double outlet right ventricle (DORV) with ventricular septal defect. She had an unbalanced chromosome translocation t (X;15) resulting in monosomy 15pter → p10 and trisomy Xq13.1 → q28. All three copies of Xq encompass the XIST gene. It is known that X chromosome inactivation could spread to the autosome part of an unbalanced translocation involving chromosome X and an autosome. To confirm the spread of X chromosome inactivation on chromosome 15, we evaluate the methylation change by the HumanMethylation450 BeadChip, a whole genome DNA methylation micorarray that includes 15,259 probes spanning 717 genes on chromosome 15. Results showed there was gain in DNA methylation of more than 20% in 586 CpG sites spanning the long arm of chromosome 15. We further examined the hypermethylated CpG sites located in CpG-island promoter, because genes subjected to X chromosome inactivation will have an increase in DNA methylation level in this region. A total of 75 sites representing 24 genes were hypermethylated. Nearly all of these probes are located in region proximal to the breakpoint, from 15q11.2 to 15q21.3 (35Mb) suggesting that X inactivation was spread to the proximal region of 15q. Gain of DNA methylation, especially in the CpG-island promoter, can result in functional inactivation of genes, and therefore could potentially worsen the phenotype of our patient.

Whole-genome array CGH evaluation for replacing prenatal karyotyping in Hong Kong.

OBJECTIVE: To evaluate the effectiveness of whole-genome array comparative genomic hybridization (aCGH) in prenatal diagnosis in Hong Kong. METHODS: Array CGH was performed on 220 samples recruited prospectively as the first-tier test study. In addition 150 prenatal samples with abnormal fetal ultrasound findings found to have normal karyotypes were analyzed as a 'further-test' study using NimbleGen CGX-135K oligonucleotide arrays. RESULTS: Array CGH findings were concordant with conventional cytogenetic results with the exception of one case of triploidy. It was found in the first-tier test study that aCGH detected 20% (44/220) clinically significant copy number variants (CNV), of which 21 were common aneuploidies and 23 had other chromosomal imbalances. There were 3.2% (7/220) samples with CNVs detected by aCGH but not by conventional cytogenetics. In the 'further-test' study, the additional diagnostic yield of detecting chromosome imbalance was 6% (9/150). The overall detection for CNVs of unclear clinical significance was 2.7% (10/370) with 0.9% found to be de novo. Eleven loci of common CNVs were found in the local population. CONCLUSION: Whole-genome aCGH offered a higher resolution diagnostic capacity than conventional karyotyping for prenatal diagnosis either as a first-tier test or as a 'further-test' for pregnancies with fetal ultrasound anomalies. We propose replacing conventional cytogenetics with aCGH for all pregnancies undergoing invasive diagnostic procedures after excluding common aneuploidies and triploidies by quantitative fluorescent PCR. Conventional cytogenetics can be reserved for visualization of clinically significant CNVs.

A prenatal case of split-hand malformation associated with 17p13.3 triplication - a dilemma in genetic counseling.

Copy number gain of 17p13.3 has been shown to be associated with developmental delay/autism and Split-Hand-Foot malformation. We report a case of fetus with bilateral split-hand malformation detected on prenatal ultrasound. Array comparative genomic hybridization detected 2 maternally inherited copy number gains in the 17p13.3 region with one of them involving the BHLHA9 gene and part of the YWHAE gene. The mother is normal in intelligence with mild right foot anomaly only. Although the BHLHA9 copy gain is known to be associated with split-hand-foot malformation, the penetrance and expressivity is highly variable. More challenging is the effect of partial YWHAE copy number gain on neurodevelopment is inconclusive based on current literature. This case highlights the difficulties of prenatal genetic counseling in array comparative genomic hybridization findings in clinical situation with incomplete understanding of genotype-phenotype correlation.

Noninvasive prenatal molecular karyotyping from maternal plasma.

Fetal DNA is present in the plasma of pregnant women. Massively parallel sequencing of maternal plasma DNA has been used to detect fetal trisomies 21, 18, 13 and selected sex chromosomal aneuploidies noninvasively. Case reports describing the detection of fetal microdeletions from maternal plasma using massively parallel sequencing have been reported. However, these previous reports were either polymorphism-dependent or used statistical analyses which were confined to one or a small number of selected parts of the genome. In this report, we reported a procedure for performing noninvasive prenatal karyotyping at 3 Mb resolution across the whole genome through the massively parallel sequencing of maternal plasma DNA. This method has been used to analyze the plasma obtained from 6 cases. In three cases, fetal microdeletions have been detected successfully from maternal plasma. In two cases, fetal microduplications have been detected successfully from maternal plasma. In the remaining case, the plasma DNA sequencing result was consistent with the pregnant mother being a carrier of a microduplication. Simulation analyses were performed for determining the number of plasma DNA molecules that would need to be sequenced and aligned for enhancing the diagnostic resolution of noninvasive prenatal karyotyping to 2 Mb and 1 Mb. In conclusion, noninvasive prenatal molecular karyotyping from maternal plasma by massively parallel sequencing is feasible and would enhance the diagnostic spectrum of noninvasive prenatal testing.

A newborn with a 790 kb chromosome 17p13.3 microduplication presenting with aortic stenosis, microcephaly and dysmorphic facial features - is cardiac assessment necessary for all patients with 17p13.3 microduplication?

While deletion of chromosome 17p13.3 (encompassing PAFAH1B1 and YWHAE genes) is known to result in Miller-Dieker syndrome (OMIM 247200), 17p13.3 microduplication gives rise to a condition commonly associated with developmental delay and autism spectrum disorder. We report a Chinese newborn presenting with dysmorphic features, microcephaly and valvar aortic stenosis, who was confirmed to have a 790 kb microduplication in chromosome 17p13.3 by array comparative genomic hybridization (aCGH). The patient passed away at 4 months of age with presumably life-threatening event associated with his cardiac condition. From literature review, congenital heart diseases of various kinds were identified in up to 20% of patients with 17p13.3 microduplication. We propose cardiac assessment should be part of the comprehensive evaluation of these patients.

Noninvasive prenatal diagnosis of fetal trisomy 18 and trisomy 13 by maternal plasma DNA sequencing.

Massively parallel sequencing of DNA molecules in the plasma of pregnant women has been shown to allow accurate and noninvasive prenatal detection of fetal trisomy 21. However, whether the sequencing approach is as accurate for the noninvasive prenatal diagnosis of trisomy 13 and 18 is unclear due to the lack of data from a large sample set. We studied 392 pregnancies, among which 25 involved a trisomy 13 fetus and 37 involved a trisomy 18 fetus, by massively parallel sequencing. By using our previously reported standard z-score approach, we demonstrated that this approach could identify 36.0% and 73.0% of trisomy 13 and 18 at specificities of 92.4% and 97.2%, respectively. We aimed to improve the detection of trisomy 13 and 18 by using a non-repeat-masked reference human genome instead of a repeat-masked one to increase the number of aligned sequence reads for each sample. We then applied a bioinformatics approach to correct GC content bias in the sequencing data. With these measures, we detected all (25 out of 25) trisomy 13 fetuses at a specificity of 98.9% (261 out of 264 non-trisomy 13 cases), and 91.9% (34 out of 37) of the trisomy 18 fetuses at 98.0% specificity (247 out of 252 non-trisomy 18 cases). These data indicate that with appropriate bioinformatics analysis, noninvasive prenatal diagnosis of trisomy 13 and trisomy 18 by maternal plasma DNA sequencing is achievable.

Non-invasive prenatal assessment of trisomy 21 by multiplexed maternal plasma DNA sequencing: large scale validity study.

OBJECTIVES: To validate the clinical efficacy and practical feasibility of massively parallel maternal plasma DNA sequencing to screen for fetal trisomy 21 among high risk pregnancies clinically indicated for amniocentesis or chorionic villus sampling. DESIGN: Diagnostic accuracy validated against full karyotyping, using prospectively collected or archived maternal plasma samples. SETTING: Prenatal diagnostic units in Hong Kong, United Kingdom, and the Netherlands. PARTICIPANTS: 753 pregnant women at high risk for fetal trisomy 21 who underwent definitive diagnosis by full karyotyping, of whom 86 had a fetus with trisomy 21. Intervention Multiplexed massively parallel sequencing of DNA molecules in maternal plasma according to two protocols with different levels of sample throughput: 2-plex and 8-plex sequencing. MAIN OUTCOME MEASURES: Proportion of DNA molecules that originated from chromosome 21. A trisomy 21 fetus was diagnosed when the z score for the proportion of chromosome 21 DNA molecules was >3. Diagnostic sensitivity, specificity, positive predictive value, and negative predictive value were calculated for trisomy 21 detection. RESULTS: Results were available from 753 pregnancies with the 8-plex sequencing protocol and from 314 pregnancies with the 2-plex protocol. The performance of the 2-plex protocol was superior to that of the 8-plex protocol. With the 2-plex protocol, trisomy 21 fetuses were detected at 100% sensitivity and 97.9% specificity, which resulted in a positive predictive value of 96.6% and negative predictive value of 100%. The 8-plex protocol detected 79.1% of the trisomy 21 fetuses and 98.9% specificity, giving a positive predictive value of 91.9% and negative predictive value of 96.9%. CONCLUSION: Multiplexed maternal plasma DNA sequencing analysis could be used to rule out fetal trisomy 21 among high risk pregnancies. If referrals for amniocentesis or chorionic villus sampling were based on the sequencing test results, about 98% of the invasive diagnostic procedures could be avoided.

Systematic identification of placental epigenetic signatures for the noninvasive prenatal detection of Edwards syndrome.

BACKGROUND: Noninvasive prenatal diagnosis of fetal aneuploidy by maternal plasma analysis is challenging owing to the low fractional and absolute concentrations of fetal DNA in maternal plasma. Previously, we demonstrated for the first time that fetal DNA in maternal plasma could be specifically targeted by epigenetic (DNA methylation) signatures in the placenta. By comparing one such methylated fetal epigenetic marker located on chromosome 21 with another fetal genetic marker located on a reference chromosome in maternal plasma, we could infer the relative dosage of fetal chromosome 21 and noninvasively detect fetal trisomy 21. Here we apply this epigenetic-genetic (EGG) chromosome dosage approach to detect Edwards syndrome (trisomy 18) in the fetus noninvasively. PRINCIPAL FINDINGS: We have systematically identified methylated fetal epigenetic markers on chromosome 18 by methylated DNA immunoprecipitation (MeDIP) and tiling array analysis with confirmation using quantitative DNA methylation assays. Methylated DNA sequences from an intergenic region between the VAPA and APCDD1 genes (the VAPA-APCDD1 DNA) were detected in pre-delivery, but not post-delivery, maternal plasma samples. The concentrations correlated positively with those of an established fetal genetic marker, ZFY, in pre-delivery maternal plasma. The ratios of methylated VAPA-APCDD1(chr18) to ZFY(chrY) were higher in maternal plasma samples of 9 male trisomy 18 fetuses than those of 27 male euploid fetuses (Mann-Whitney test, P=0.029). We defined the cutoff value for detecting trisomy 18 fetuses as mean+1.96 SD of the EGG ratios of the euploid cases. Eight of 9 trisomy 18 and 1 of 27 euploid cases showed EGG ratios higher than the cutoff value, giving a sensitivity of 88.9% and a specificity of 96.3%. CONCLUSIONS: Our data have shown that the methylated VAPA-APCDD1 DNA in maternal plasma is predominantly derived from the fetus. We have demonstrated that this novel fetal epigenetic marker in maternal plasma is useful for the noninvasive detection of fetal trisomy 18.

Prenatal findings and delineation of de novo concurrent partial trisomy 7q(7q31.2 --> qter) and partial monosomy 6q(6q26 --> qter) by high-resolution array CGH.

OBJECTIVE: We investigated the application of microarray-based comparative genomic hybridization (array CGH) on a fetus showing hemivertebrae and intra-abdominal mass at 15 weeks. METHODS: Conventional karyotyping and high-resolution array CGH techniques using 244K CGH microarray were performed to investigate the possibility of genomic imbalance on the opted chorionic villus sample. RESULTS: G-banded fetal chromosome analysis showed 46,XY,der(6)t(6;7)(q26;q31.2)pat. Whole genome scan by array CGH fine mapped the origin of the aberrant chromosomes to be a partial single copy gain of 42.5 Mb from chromosome region 7:116266547 --> qter and concurrent partial single copy loss of 8.1 Mb from chromosome region 6:162756975 --> qter. Pathological examination of the abortus showed gastrointestinal malformations, hemivertebrae with scoliosis, clinodactyly and club feet. CONCLUSIONS: Prenatal and perinatal findings of concurrent trisomy 7q and monosomy 6q were unique. This study demonstrated array CGH can interrogate the entire genome at a resolution and rapidity unattainable by conventional cytogenetic techniques and may have wide application in prenatal diagnosis.

Chromosomal anomalies and Y-microdeletions among Chinese subfertile men in Hong Kong.

OBJECTIVE: To report the type and frequency of chromosomal anomalies and Y-microdeletions among Hong Kong Chinese subfertile men with sperm concentrations lower than 5 million/mL. DESIGN. Retrospective study. SETTING: A reproductive centre in Hong Kong. PARTICIPANTS: A total of 295 Chinese subfertile men who underwent both karyotyping and Y-microdeletion studies from 2000 to 2007 were categorised as having non-obstructive azoospermia (n=71), very severe oligospermia (sperm concentration>0 and 2 and <5 million/mL, n=66). MAIN OUTCOME MEASURES: Karyotyping and Y-microdeletion studies. RESULTS: The prevalence of chromosomal anomalies and Y-microdeletions in the study population were 8.5% (25/295; 95% confidence interval, 5.6-12.3%) and 6.4% (19/295; 3.9-9.9%), respectively. The total prevalence of chromosomal anomalies and Y-microdeletions was 13.2% (39/295; 95% confidence interval, 9.6-17.6%) as five cases of non-obstructive azoospermia showed both Y structural alterations and AZFbc deletion. The corresponding figures for chromosomal anomalies in the groups with non-obstructive azoospermia, very severe oligospermia, and severe oligospermia were 21.1% (15/71; 95% confidence interval, 12.3-32.4%), 5.7% (9/158; 2.6-10.5%), and 1.5% (1/66; 0.0-8.2%). While for Y-microdeletions they were 8.5% (6/71; 3.2-17.5%), 8.2% (13/158; 4.5-13.7%) and 0% (0/66; 0.0-4.4%), respectively. The respective overall prevalence rates for chromosomal anomalies and Y-microdeletions in these groups were: 22.5% (16/71; 13.5-34.0%), 13.9% (22/158; 8.9-20.3%), and 1.5% (1/66; 0.0-8.2%). CONCLUSIONS: Our findings strongly support the recommendation for both karyotyping and Y-microdeletion analyses in subfertile men with sperm concentrations of 2 million/mL or lower before they undergo assisted reproduction treatment.