Cost-effectiveness analysis of chromosomal microarray as a primary test for prenatal diagnosis in Hong Kong.

BACKGROUND: Chromosomal microarray (CMA) has been shown to be cost-effective over karyotyping in invasive prenatal diagnosis for pregnancies with fetal ultrasound anomalies. Yet, information regarding preceding and subsequent tests must be considered as a whole before the true cost-effectiveness can emerge. Currently in Hong Kong, karyotyping is offered free as the standard prenatal test while genome-wide array comparative genome hybridization (aCGH), a form of CMA, is self-financed. A new algorithm was proposed to use aCGH following quantitative fluorescent polymerase chain reaction (QF-PCR) as primary test instead of karyotyping. This study aims to evaluate the cost-effectiveness of the proposed algorithm versus the current algorithm for prenatal diagnosis in Hong Kong. METHODS: Between November 2014 and February 2016, 129 pregnant women who required invasive prenatal diagnosis at two public hospitals in Hong Kong were prospectively recruited. The proposed algorithm was performed for all participants in this demonstration study. For the cost-effectiveness analysis, cost and outcome (diagnostic rate) data were compared with that of a hypothetical scenario representing the current algorithm. Further analysis was performed to incorporate women's willingness-to-pay for the aCGH test. Impact of government subsidies on the aCGH test was explored as a sensitivity analysis. RESULTS: The proposed algorithm dominated the current algorithm for prenatal diagnosis. Both algorithms were equally effective but the proposed algorithm was significantly cheaper (p ≤ 0.05). Taking into account women's willingness-to-pay for an aCGH test, the proposed algorithm was more effective and less costly than the current algorithm. When the government subsidy reaches 100%, the maximum number of diagnoses could be made. CONCLUSION: By switching to the proposed algorithm, cost saving can be achieved whilst maximizing the diagnostic rate for invasive prenatal diagnosis. It is recommended to implement aCGH as a primary test following QF-PCR to replace the majority of karyotyping for prenatal diagnosis in Hong Kong.

Paternal uniparental disomy of chromosome 19 in a pair of monochorionic diamniotic twins with dysmorphic features and developmental delay.

BACKGROUND: We report here clinical, cytogenetic and molecular data for a pair of monochorionic diamniotic twins with paternal isodisomy for chromosome 19. Both twins presented with dysmorphic features and global developmental delay. This represents, to our knowledge, the first individual human case of paternal uniparental disomy for chromosome 19 (UPD19). METHODS: Whole-exome sequencing, together with conventional karyotype and SNP array analysis were performed along with genome-wide DNA methylation array for delineation of the underlying molecular defects. RESULTS: Conventional karyotyping on amniocytes and lymphocytes showed normal karyotypes for both twins. Whole-exome sequencing did not identify any pathogenic sequence variants but >5000 homozygous exonic variants on chromosome 19, suggestive of UPD19. SNP arrays on blood and buccal DNA both showed paternal isodisomy for chromosome 19. Losses of imprinting for known imprinted genes on chromosome 19 were identified, including ZNF331, PEG3, ZIM2 and MIMT1. In addition, imprinting defects were also identified in genes located on other chromosomes, including GPR1-AS, JAKMP1 and NHP2L1. CONCLUSION: Imprinting defects are the most likely cause for the dysmorphism and developmental delay in this first report of monozygotic twins with UPD19. However, epigenotype-phenotype correlation will require identification of additional individuals with UPD19 and further molecular analysis.

A fetus coexisting with a complete hydatidiform mole with trisomy 9 of maternal origin.

A complete hydatidiform mole (CHM) coexisting with a viable fetus is a rare finding in pregnancies. Accurate diagnosis often relies on ultrasonographic, histopathological and molecular techniques in the definite diagnosis. To the best of our knowledge, a liveborn fetus coexisting with CHM with trisomy 9 has not been described. The use of molecular genotyping and immunohistochemical laboratory investigations enabled the CHM to be fully characterized. Postzygotic diploidization of a triploid conception arising from dispermy is the proposed mechanism of its formation.

Bridging the gap from prenatal karyotyping to whole-genome array comparative genomic hybridization in Hong Kong: survey on knowledge and acceptance of health-care providers and pregnant women.

PURPOSE: The use of array comparative genomic hybridization (aCGH) has been increasingly widespread. The challenge of integration of this technology into prenatal diagnosis was the interpretation of results and communicating findings of unclear clinical significance. This study assesses the knowledge and acceptance of prenatal aCGH in Hong Kong obstetricians and pregnant women. The aim is to identify the needs and gaps before implementing the replacement of karyotyping with aCGH. Questionnaires with aCGH information in the form of pamphlets were sent by post to obstetrics and gynecology doctors. METHOD: For the pregnant women group, a video presentation, pamphlets on aCGH and a self-administered questionnaire were provided at the antenatal clinic. RESULT: The perception of aCGH between doctors and pregnant women was similar. Doctors not choosing aCGH were more concerned about the difficulty in counseling of variants of unknown significance and adult-onset disease in pregnant women, whereas pregnant women not choosing aCGH were more concerned about the increased waiting time leading to increased anxiety. Prenatal aCGH is perceived as a better test by both doctors and patients. CONCLUSION: Counseling support, training, and better understanding and communication of findings of unclear clinical significance are necessary to improve doctor-patient experience.

Fetal Hyperthyroidism with Maternal Hypothyroidism: Two Cases of Intrauterine Therapy.

Fetal hyperthyroidism can occur secondary to maternal autoimmune hyperthyroidism. The thyroid-stimulating hormone receptor antibody (TRAb) transferred from the mother to the fetus stimulates the fetal thyroid and causes fetal thyrotoxicosis. Fetuses with this condition are difficult to detect, especially after maternal Graves disease therapy. Here, we present two cases of fetal hyperthyroidism with maternal hypothyroidism and review the assessment and intrauterine therapy for fetal hyperthyroidism. Both women were referred at 22+ and 23+ weeks of gestation with abnormal ultrasound findings, including fetal heart enlargement, pericardial effusion, and fetal tachycardia. Both women had a history of Graves disease while in a state of hypothyroidism with a high titer of TRAb. A sonographic examination showed a diffusely enlarged fetal thyroid with abundant blood flow. Invasive prenatal testing revealed no significant chromosomal aberration. Low fetal serum TSH and high TRAb levels were detected in the cord blood. Fetal hyperthyroidism was considered, and maternal oral methimazole (MMI) was administered as intrauterine therapy, with the slowing of fetal tachycardia, a reduction in fetal heart enlargement, and thyroid hyperemia. During therapy, maternal thyroid function was monitored, and the dosage of maternal levothyroxine was adjusted accordingly. Both women delivered spontaneously at 36+ weeks of gestation, and neonatal hyperthyroidism was confirmed in both newborns. After methimazole and propranolol drug treatment with levothyroxine for 8 and 12 months, both babies became euthyroid with normal growth and development.

Outcome of twin pregnancies after amniocentesis.

AIM: The aim of this study was to assess the miscarriage and fetal loss rates of twin pregnancies after amniocentesis. MATERIAL AND METHODS: The outcome of 140 twin pregnancies that had amniocentesis performed from 1997 to 2006 was reviewed. RESULTS: Among 140 twin pregnancies with amniocentesis, 35 were excluded (fetuses with structural anomalies, post-selective feticide, abnormal fetal karyotype, twin-twin transfusion syndrome [TTTS], termination of pregnancy, and unknown outcome). For the remaining 105 twin pregnancies, 102 had live births of all fetuses. One dichorionic twin had silent miscarriage of one fetus at 23 weeks. Another dichorionic twin had intrauterine death of one fetus at unknown gestation. One patient had preterm delivery at 32 weeks with neonatal death of one twin due to severe intrauterine growth restriction. The miscarriage rate (one or both fetuses) for twins before 24 weeks was 0.96% (1/105), the pregnancy loss (one or both fetuses) within 4 weeks of amniocentesis was 0.96% (1/105). The total fetal loss rate was 0.96% (2/210) for twins. CONCLUSION: Our cohort showed a low fetal loss rate after amniocentesis for uncomplicated twin pregnancies.

Maternal serum anti-Mullerian hormone level is not superior to chronological age in predicting Down syndrome pregnancies.

OBJECTIVE: To compare the difference in maternal serum anti-Mullerian hormone (AMH) level between Down syndrome pregnancies and unaffected pregnancies, and to evaluate its performance as a screening marker for Down syndrome pregnancy. METHOD: A total of 145 pregnancies affected by foetal Down syndrome and 290 unaffected controls matched with maternal age and gestational age were selected, and their archived first or second trimester serum retrieved for AMH assay. RESULTS: There was no significant difference in maternal serum AMH level between pregnancies affected and unaffected by foetal Down syndrome. Our first trimester serum samples had higher AMH concentration compared to second trimester samples. CONCLUSIONS: Maternal serum AMH level, as a marker of ovarian age, is not superior to chronological age in predicting Down syndrome pregnancies. Despite the cross-sectional nature of our study, the variation of maternal serum AMH concentration with gestational age warrants further investigation.

Prenatal diagnosis and long-term follow-up of a Chinese patient with mosaic variegated aneuploidy and its molecular analysis.

Mosaic variegated aneuploidy (MVA) is a rare genetic disorder caused by mutations in BUB1B, CEP57, or TRIP13. We describe the prenatal diagnosis, molecular characterization, and clinical management of a long-lived patient with BUB1B-related MVA.

Expanded Carrier Screening in Chinese Population - A Survey on Views and Acceptance of Pregnant and Non-Pregnant Women.

OBJECTIVE: Recessive genetic diseases impose physical and psychological impacts to both newborns and parents who may not be aware of being carriers. Expanded carrier screening (ECS) allows screening for multiple genetic conditions at the same time. Whether or not such non-targeted panethnic approach of genetic carrier screening should replace the conventional targeted approach remains controversial. There is limited data on view and acceptance of ECS in general population, as well as the optimal timing of offering ECS to women. This study assesses views and acceptance of ECS in both pregnant women and non-pregnant women seeking fertility counseling or checkup and their reasons for accepting or declining ECS. MATERIALS AND METHODS: This is a questionnaire survey with ECS information in the form of pamphlets distributed from December 2016 to end of 2018. Women were recruited from the antenatal clinics and the assisted reproductive unit at the Department of Obstetrics and Gynaecology, Queen Mary Hospital and the prepregnancy counseling clinic at the Family Planning Association of Hong Kong. RESULTS: A total of 923 women were recruited: 623 pregnant women and 300 non-pregnant women. There were significantly more non-pregnant women accepting ECS compared to pregnant women (70.7% vs. 61.2%). Eight hundred and sixty-eight (94%) women perceived ECS as at least as effective as or superior to traditional targeted screening. Significantly more pregnant women have heard about ECS compared with non-pregnant women (42.4% vs. 32.3%, P = 0.0197). Majority of women showed lack of understanding about ECS despite reading pamphlets that were given to them prior to filling in the questionnaires. Cost of ECS was a major reason for declining ECS, 28% (n = 256). Significantly more pregnant women worried about anxiety caused by ECS compared with the non-pregnant group (21.1% vs. 7.4%, P = 0.0006). CONCLUSION: Our study demonstrates that expanded carrier screening was perceived as a better screening by most women. Prepregnancy ECS maybe a better approach than ECS during pregnancy, as it allows more reproductive options and may cause less anxiety. Nevertheless, implementation of universal panethnic ECS will need more patient education, ways to reduce anxiety, and consensus on optimal timing in offering ECS.

Health professionals' involvement and information provision in genetic counseling following prenatal diagnosis of sex chromosome aneuploidy in Hong Kong.

This study supports training in genetic counseling for obstetricians and adoption of a multidisciplinary approach in the counseling process following prenatal diagnosis of sex chromosome aneuploidy.

The effect of volume of chorionic villi on long-term cell culture.

OBJECTIVE: It was the aim of our study to investigate the association between culture time and weight of villi obtained by transabdominal chorionic villus sampling (CVS). METHODS: We analyzed 1,442 villus samples. RESULTS: The gestational age at sampling ranged from 10 to 14 weeks. The weight of villi in these samples ranged from 1 to 80 mg (median 10 mg, interquatile range 7-12 mg). The culture time ranged from 5 to 24 days. Culture time was significantly and inversely correlated with the weight of villi obtained (r = -0.258, p < 0.01). Time was significantly longer when 5 mg or less of villi was obtained but the difference was only up to 2 days. CONCLUSIONS: Because the difference in culture time for different groups of villus samples was within 1-2 days, this relationship is statistically significant but has no clinical significance.

Use of clinical chromosomal microarray in Chinese patients with autism spectrum disorder-implications of a copy number variation involving DPP10.

BACKGROUND: Array comparative genomic hybridization (aCGH) is recommended as a first-tier genetic test for children with autism spectrum disorder (ASD). However, interpretation of results can often be challenging partly due to the fact that copy number variants (CNVs) in non-European ASD patients are not well studied. To address this literature gap, we report the CNV findings in a cohort of Chinese children with ASD. METHODS: DNA samples were obtained from 258 Chinese ASD patients recruited from a child assessment center between January 2011 and August 2014. aCGH was performed using NimbleGen-CGX-135k or Agilent-CGX 60k oligonucleotide array. Results were classified based on existing guidelines and literature. RESULTS: Ten pathogenic CNVs and one likely pathogenic CNV were found in nine patients, with an overall diagnostic yield of 3.5%. A 138 kb duplication involving 3' exons of DPP10 (arr[GRCh37] 2q14.1(116534689_116672358)x3), reported to be associated with ASD, was identified in one patient (0.39%). The same CNV was reported as variant of uncertain significance (VUS) in DECIPHER database. Multiple individuals of typical development carrying a similar duplication were identified among our ancestry-matched control with a frequency of 6/653 (0.92%) as well as from literature and genomic databases. CONCLUSIONS: The DPP10 duplication is likely a benign CNV polymorphism enriched in Southern Chinese with a population frequency of ~1%. This highlights the importance of using ancestry-matched controls in interpretation of aCGH findings.

Human chorionic gonadotropin and plasma protein-A in alpha0-thalassemia pregnancies.

OBJECTIVE: Maternal serum free beta-human chorionic gonadotropin (beta-hCG) and pregnancy-associated plasma protein-A (PAPP-A) have been used effectively in the screening of Down syndrome in the first trimester. In this study, we aim to measure the value of first-trimester maternal serum free beta-hCG and PAPP-A as predictors of homozygous alpha0-thalassemia-affected pregnancies. METHODS: Free beta-hCG and PAPP-A concentrations were measured in stored maternal serum samples obtained at 12 weeks of gestation from 22 women with fetuses affected by homozygous alpha0-thalassemia and from 436 controls matched for maternal age, ethnicity, and weight, as well as gestation at blood sampling. RESULTS: Maternal serum concentration of free beta-hCG was significantly increased in women with pregnancies affected by homozygous alpha0-thalassemia than in controls (P = .001). Concentrations of PAPP-A did not differ between the cases affected by homozygous alpha0-thalassemia and the controls (P = .652). CONCLUSION: Pregnancies affected by homozygous alpha0-thalassemia are associated with increased maternal serum free beta-hCG at 11-14 weeks of gestation. This serum analyte alone may not be clinically useful as a predictor of pregnancies affected by homozygous alpha0-thalassemia. However, the absence of ultrasound features of fetal anemia and hydropic changes, together with normal maternal serum free beta-hCG and PAPP-A in the first trimester, will be reassuring signs of normality for fetuses at risk of homozygous alpha0-thalassemia and, hence, enable women to avoid invasive tests in unaffected pregnancies.

Effectiveness of a Technology-Based Injury Prevention Program for Enhancing Mothers' Knowledge of Child Safety: Protocol for a Randomized Controlled Trial.

BACKGROUND: Provision of anticipatory guidance for parents is recommended as an effective strategy to prevent injuries among young children. Technology-based anticipatory guidance has been suggested to reinforce the effectiveness of injury prevention and improve parents' knowledge of child safety. OBJECTIVE: This study aims to examine the effectiveness of a technology-based injury prevention program with parental anticipatory guidance for enhancing mothers' knowledge of child safety. METHODS: In this randomized controlled trial, 308 mothers will be recruited from the antenatal clinics and postnatal wards of two major public hospitals in Hong Kong. Participating mothers will be randomly assigned into intervention and control groups. Mothers in the intervention group will be given free access to a technology-based injury prevention program with anticipatory guidance, whereas mothers in the control group will be given a relevant booklet on parenting. The injury prevention program, available as a website or on a mobile app, includes behavioral components based on the Theory of Planned Behavior. The primary outcome measure will be the change in the mother's knowledge of child safety. The secondary outcome measures will be age-appropriate domestic safety knowledge, attitudes, intentions, perceived behavioral control, and self-reported behavior related to home safety practice. We will also determine dose-response relationships between the outcome measures and the website and mobile app usage. RESULTS: Enrolment of participants will begin in October 2016. Results are expected by June 2018. CONCLUSIONS: Parents will be able to easily access the domestic injury prevention website to find information regarding child injury prevention. It is anticipated that the technology-based intervention will help parents improve their knowledge of child safety and raise their awareness about the consequences of domestic injuries and the importance of prevention. TRIAL REGISTRATION: Clinicaltrials.gov Clinicaltrials.gov NCT02835768; http://clinicaltrials.gov/ct2/show/NCT02835768 (Archived by WebCite at http://www.webcitation/6lbXYM6b9).

Diagnostic yield of array CGH in patients with autism spectrum disorder in Hong Kong.

BACKGROUND: Chromosomal microarray offers superior sensitivity for identification of submicroscopic copy number variants (CNV) and it is advocated to be the first tier genetic testing for patients with autism spectrum disorder (ASD). In this regard, diagnostic yield of array comparative genomic hybridization (CGH) for ASD patients is determined in a cohort of Chinese patients in Hong Kong. METHODS: A combined adult and paediatric cohort of 68 Chinese ASD patients (41 patients in adult group and 27 patients in paediatric group). The genomic DNA extracted from blood samples were analysed by array CGH using NimbleGen CGX-135K oligonucleotide array. RESULTS: We identified 15 CNV and eight of them were clinically significant. The overall diagnostic yield was 11.8 %. Five clinically significant CNV were detected in the adult group and three were in the paediatric group, providing diagnostic yields of 12.2 and 11.1 % respectively. The most frequently detected CNV was 16p13.11 duplications which were present in 4 patients (5.9 % of the cohort). CONCLUSIONS: In this study, a satisfactory diagnostic yield of array CGH was demonstrated in a Chinese ASD patient cohort which supported the clinical usefulness of array CGH as the first line testing of ASD in Hong Kong.

Can amnio-polymerase chain reaction alone replace conventional cytogenetic study for women with positive biochemical screening for fetal Down syndrome?

To determine whether amnio-polymerase chain reaction (amnio-PCR) can replace conventional cytogenetic study for confirming the karyotype of fetuses in women with positive biochemical screening for fetal Down syndrome. To check the accuracy of this technique in our laboratory, we first compared the amnio-PCR results with those of conventional cytogenetic study in 235 patients referred from June 1999 to December 2001 for prenatal diagnosis in a referral center in Hong Kong. We then reviewed the results of 1526 amniotic fluid cultures performed for positive fetal Down syndrome screening between January 1997 and December 2001 and classified them as detectable or not detectable by amnio-PCR, using the assumption that we had replaced conventional cytogenetic study with amnio-PCR. The 235 amnio-PCR results were all informative, without a false-positive or false-negative result. Of the 1526 cases with positive fetal Down syndrome screening and no ultrasound abnormalities, only two cases of sex chromosome abnormalities and two cases of marker chromosomes would have been missed if conventional cytogenetic study had been replaced by amnio-PCR.Amnio-PCR can be an alternative to conventional cytogenetic study for women with positive biochemical screening for fetal Down syndrome and no demonstrable fetal structural abnormality.

Cystic hygroma detected in the first trimester scan in Hong Kong.

OBJECTIVE: To investigate the outcome of fetuses with cystic hygroma (CH) diagnosed at the first trimester from a general population in Hong Kong. METHOD: This was a prospective study of 30 fetal cystic hygroma detected at 11 to 13 + 6 weeks' gestation in 8835 sequential unselected pregnancies. Fetal cystic hygroma was categorized as isolated cystic hygroma (ICH) or associated cystic hygroma (ACH) according to the presence of associated multiple congenital structural abnormalities (MCA). RESULTS: There were 10 cases of ICH and 20 cases of ACH. The karyotypes were obtained in 29 cases. In the ICH, 30% (3/10) were associated with chromosomal abnormalities. In the ACH, 65% (13/20) were associated with major chromosomal abnormalities. CONCLUSION: This study suggests that the prognosis of cystic hygroma detected in the first trimester is guarded, with high incidence of MCA (66.7%, 20/30) and chromosomal abnormalities (53.3%, 16/30). The findings support detailed ultrasound examination and invasive prenatal diagnosis for cystic hygroma.

Molecular basis of von Hippel-Lindau syndrome in Chinese patients.

BACKGROUND: Von Hippel-Lindau (VHL) syndrome is an autosomal dominant familial cancer syndrome predisposing the affected individuals to multiple tumours in various organs. The genetic basis of VHL in Southern Chinese is largely unknown. In this study, we characterized the mutation spectrum of VHL in nine unrelated Southern Chinese families. METHODS: Nine probands with clinical features of VHL, two symptomatic and eight asymptomatic family members were included in this study. Prenatal diagnosis was performed twice for one proband. Two probands had only isolated bilateral phaeochromocytoma. The VHL gene was screened for mutations by polymerase chain reaction, direct sequencing and multiplex ligation-dependent probe amplification (MLPA). RESULTS: The nine probands and the two symptomatic family members carried heterozygous germline mutations. Eight different VHL mutations were identified in the nine probands. One splicing mutation, NM_000551.2: c.463+1G > T, was novel. The other seven VHL mutations, c.233A > G [p.Asn78Ser], c.239G > T [p.Ser80Ile], c.319C > G [p.Arg107Gly], c.481C > T [p.Arg161X], c.482G > A [p.Arg161Gln], c.499C > T [p.Arg167Trp] and an exon 2 deletion, had been previously reported. Three asymptomatic family members were positive for the mutation and the other five tested negative. In prenatal diagnosis, the fetuses were positive for the mutation. CONCLUSIONS: Genetic analysis could accurately confirm VHL syndrome in patients with isolated tumours such as sporadic phaeochromocytoma or epididymal papillary cystadenoma. Mutation detection in asymptomatic family members allows regular tumour surveillance and early intervention to improve their prognosis. DNA-based diagnosis can have an important impact on clinical management for VHL families.

First-trimester fetal limb biometry in Chinese population.

OBJECTIVES: To establish reference ranges for fetal limb biometry obtained by transabdominal ultrasound examination at 12-14 weeks of gestation in Chinese women. METHODS: A total of 1489 normal singleton fetuses between 12(+0) and 14(+6) weeks of gestation were examined transabdominally by two experienced observers. The gestation was ascertained by measurement of fetal crown-rump length (CRL) or biparietal diameter (BPD) and head circumference (HC). The lengths of the humerus and femur were prospectively worked out. RESULTS: Gestation-specific reference ranges for limb measurements were calculated. The femur length (FL) (mean +/- SD) was 9.15 +/- 1.44 mm at 12-12(+6) weeks, 11.45 +/- 1.35 mm at 13-13(+6) weeks, and 13.64 +/- 1.60 mm at 14-14(+6) weeks; the corresponding humerus length (HL) (mean +/- SD) was 9.63 +/- 1.44 mm, 12.01 +/- 1.41 mm, 14.29 +/- 1.48 mm, respectively. CONCLUSIONS: There was a general increase in fetal limb biometry with gestation. Fetal limb length can be an early marker of early growth restriction as well as fetal skeletal dysplasia among women in the local population.