Yiu Man Chan

Women's uptake of non‐invasive DNA testing following a high‐risk screening test for trisomy 21 within a publicly funded healthcare system: findings from a retrospective review

The objective of the study was to evaluate the uptake of non‐invasive cell‐free fetal DNA screening test (NIDT) after a high‐risk screening result for trisomy 21

Chinese women's preferences for prenatal diagnostic procedure and their willingness to trade between procedures.

To assess Chinese womens preference for the choice of a prenatal diagnosis test, karyotyping or rapid aneuploidy, and its relationship to maternal psychological state.

Impact of replacing Chinese ethnicity‐specific fetal biometry charts with the INTERGROWTH‐21st standard

To assess the impact of adopting the INTERGROWTH‐21st biometry standards in a Chinese population.

Miscarriage after invasive prenatal diagnostic procedures: how much risk our pregnant women are willing to take?

To elicit the level of risk of prenatal diagnostic procedure‐related miscarriage that Chinese pregnant women were willing to accept.

Patient's Choice between a Non-Invasive Prenatal Test and Invasive Prenatal Diagnosis Based on Test Accuracy

Objective: To assess how pregnant women choose between a non-invasive DNA test (NIDT) and an invasive prenatal test (IPD) based on the accuracy of the test. Materials and Methods: Pregnant women who attended for first-trimester combined screening assessment of risk of Down syndrome were invited to participate in an interviewer-administered survey. Women were asked to choose between NIDT (variable detection rate but no miscarriage risk) and IPD (∼100% detection rate but 0.5-1% miscarriage risk) if their screening test was positive for Down syndrome using the standard gamble technique. Results: 358 women were approached of which 106 (29.6%) were unwilling to participate in the study as it had already been decided in advance which additional test they would have if they were screened positive. Of these 106 women, 70 (19.6%) would only choose IPD whereas 36 (10%) would only choose NIDT. Among those who agreed to undertake the gamble and participate in the study (n = 252), 50% were willing to accept NIDT as an alternative to IPD provided that NIDT had a detection rate of 95%. Conclusion: The majority can accept NIDT as an alternative to IPD provided that the test is 95% accurate in the diagnosis of Down syndrome. Current evidence indicates that the detection rate of NIDT will be higher than this level. Health professionals should consider NIDT as an alternative to IPD when counseling women with a positive screening test.

Increased bone turnover, osteoporosis, progressive tibial bowing, fractures, and scoliosis in a patient with a final-exon SATB2 frameshift mutation.

Haploinsufficiency of SATB2 causes cleft palate, intellectual disability with deficient speech, facial and dental abnormalities, and other variable features known collectively as SATB2‐associated syndrome. This phenotype was accompanied by osteoporosis, fractures, and tibial bowing in two previously reported adult patients; each possessed SATB2 mutations either predicted or demonstrated to escape nonsense‐mediated decay, suggesting that the additional bone defects result from a dominant negative effect and/or age‐dependent penetrance. These hypotheses remain to be confirmed, as do the specific downstream defects causing bone abnormalities. We report a SATB2 mutation (c.2018dupA; p.(H673fs)) in a 15‐year‐old patient whose SATB2‐associated syndrome phenotype is accompanied by osteoporosis, fractures, progressive tibial bowing, and scoliosis. As this homeodomain‐disrupting and predicted truncating mutation resides within the final exon of SATB2, escape from nonsense‐mediated decay is likely. Thus, we provide further evidence of bone phenotypes beyond those typically associated with SATB2‐associated syndrome in individuals with potential dominant‐negative SATB2 alleles, as well as evidence for age‐dependence of bone features. Elevations in alkaline phosphatase, urinary N‐telopeptide/creatinine ratio, and osteocalcin in the patient indicate increased bone turnover. We propose surveillance and treatment with osteoclast inhibitors to prevent fractures and to slow progressive bone deformities.

Prospective Assessment of the INTERGROWTH‐21 and WHO Estimated Fetal Weight Reference Curve

To assess the suitability of the new INTERGROWTH‐21st and World Health Organization (WHO) estimated fetal weight (EFW) references in a Southern Chinese population. A secondary aim was to determine the accuracy of EFW by assessing the difference between EFW and actual birth weight.

Prospective assessment of INTERGROWTH‐21st and World Health Organization estimated fetal weight reference curves

To assess the suitability of the new INTERGROWTH‐21st and World Health Organization (WHO) estimated fetal weight (EFW) references in a Southern Chinese population. A secondary aim was to determine the accuracy of EFW by assessing the difference between EFW and actual birth weight.

EP06.02: Prenatal visualisation of paraumbilical veins in a fetus with umbilical vein stricture: Electronic Poster Abstracts

gestation. The definitive diagnosis was confirmed with postnatal simple x-ray and genetic testing. Results: Eighteen fetuses underwent fetal CT. In 50% of them an ultrasound-based diagnosis was changed due to fetal CT. Under-ossification of metaphysis and calvarium were found while ossification of ribs and vertebral bodies was not detected by ultrasound. In contrast, with fetal CT, short and thin ribs, deep cuppings of metaphysis were determined and in severe cases fetal CT revealed the absence of ossification of calvarium, skull base and face, partial defects of vertebral bodies and thin and short ribs. These findings were confirmed with postnatal simple x-ray of the newborns. Conclusions: In order to make a prenatal diagnosis of HPP, simple ultrasound alone could be insufficient. Additional fetal CT would help to make an accurate diagnosis by enabling one to examine fetal bones with more precision. In addition to the shortening and deformity of long bones by ultrasound, flared metaphysis and absence of skull are useful signs for fetal diagnosis, which could be easily detected by fetal CT. Furthermore, fetal CT could be used to assess the severity of HPP by examining poor ossifications of trunk bones such as vertebral bodies and ribs of the fetuses.

Identification of fragile X pre-mutation carriers in the Chinese obstetric population using a robust FMR1 polymerase chain reaction assay: implications for screening and prenatal diagnosis

INTRODUCTION There is significant morbidity associated with fragile X syndrome. Unfortunately, most maternal carriers are clinically silent during their reproductive years. Because of this, many experts have put forward the notion of preconception or prenatal fragile X carrier screening for females. This study aimed to determine the prevalence of fragile X syndrome pre-mutation and asymptomatic full-mutation carriers in a Chinese pregnant population, and the distribution of cytosine-guanine-guanine (CGG) repeat numbers using a robust fragile X mental retardation 1 (FMR1) polymerase chain reaction assay. METHODS This was a cross-sectional survey in prospectively recruited pregnant women from a university hospital in Hong Kong. Chinese pregnant women without a family history of fragile X syndrome were recruited between April 2013 and May 2015. A specific FMR1 polymerase chain reaction assay was performed on peripheral blood to determine the CGG repeat number of the FMR1 gene. Prenatal counselling was offered to full-mutation and pre-mutation carriers. RESULTS In 2650 Chinese pregnant women, two individuals with pre-mutation alleles (0.08%, one in 1325) and one asymptomatic woman with full-mutation (0.04%, one in 2650) alleles were identified. The overall prevalence of pre-mutation and full-mutation alleles was 0.11% (1 in 883). Furthermore, 30 (1.1%) individuals with intermediate alleles were detected. In the 2617 women with normal CGG repeats, the most common CGG repeat allele was 30. CONCLUSIONS The overall prevalence of pre-mutation and asymptomatic full-mutation carriers in the Chinese pregnant population was one in 883, detected by a new FMR1 polymerase chain reaction assay.