Publications by authors named "Mary Hoi Yin Tang"

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.

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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.

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

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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.

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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.

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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).

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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.

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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.

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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.

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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.

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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).

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A low level of PAPP-A predicts adverse fetal outcomes. As Chinese pregnant women have a higher level of PAPP-A, the predictive performance of PAPP-A and its optimal cutoff value might be different. This study aims to establish a PAPP-A cutoff value in the Chinese population that identifies adverse fetal outcomes.

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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).

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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).

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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.

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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.

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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.

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Hemivertebra is a rare congenital spinal disorder where only one side of the vertebral body develops, leading to deformation of the spine, such as scoliosis or kyphosis. Previous reports suggest that the diagnosis may be based on antenatal sonographic examination after 14 weeks. We present the sonographic features of a fetus with solitary hemivertebra at 13 weeks' gestation confirmed by postmortem babygram, magnetic resonance imaging (MRI) and pathological examination.

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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).

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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.

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Purpose Of Review: Nuchal translucency is one of the important markers in the first trimester during antenatal screening for fetal Down's syndrome. With the observation of alterations in biochemical markers in pregnancies conceived after assisted reproduction, this review presents current information related to the thickness of nuchal translucency in these pregnancies.

Recent Findings: Early small studies did not demonstrate any discrepancy in the thickness of nuchal translucency in fetuses from assisted reproduction and from spontaneous pregnancies, but there has been recent evidence to suggest an increased level of nuchal translucency in singletons from various modes of assisted-reproduction technology.

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Objectives: Absence of the nasal bone in fetuses with trisomy 21 is a potential ultrasound marker for Down syndrome from the first trimester onwards. Racial differences in fetal nasal bone length have been reported. There was no reference range for the first-trimester fetal nasal bone length (NBL) in the Chinese population.

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Lethal multiple pterygium syndrome is a rare inherited disorder. Previous reports suggest that the diagnosis may be based on prenatal sonographic demonstration of severe limb flexion, absence of fetal motion, and a large cystic hygroma in the second and third trimesters. We present the sonographic features and postmortem features of a fetus with lethal multiple pterygium syndrome at 13 weeks of gestation, which shows that the condition can possibly be diagnosed in the first trimester of pregnancy.

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Objective: Maternal serum pregnancy-associated plasma protein-A (PAPP-A) and free beta-human chorionic gonadotrophin (beta-hCG) are useful markers in the screening of Down syndrome in the first trimester. We investigated the effect of intracytoplasmic sperm injection (ICSI), freezing and thawing of embryos on the levels of these two analytes in assisted reproduction pregnancies.

Methods: We recruited 149 women who conceived after assisted reproduction with fresh embryos (92 from conventional IVF and 57 from ICSI), 85 women who conceived with frozen-thawed embryos (54 from conventional IVF and 31 from ICSI) and 401 women with spontaneous conceptions as controls.

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