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Objective: To review medical records of pregnant women with positive non-invasive prenatal testing (NIPT) results for sex chromosome abnormalities who attended Tuen Mun hospital between 2015 and 2021. Patient decision after prenatal diagnosis, confirmatory diagnostic testing results, and pregnancy/neonatal outcomes were summarised. Methods: Medical records of women with abnormal NIPT results for sex chromosome abnormalities who attended Tuen Mun Hospital between January 2015 and December 2021 were retrospectively reviewed. Results: 56 Chinese women attended our prenatal diagnostic clinic with abnormal NIPT results for sex chromosome abnormalities involving 45, X (n=17), 47, XXY (n=10), 47, XXX (n=6), 47, XYY (n=8), disproportionate level of sex chromosomes (n=9), copy number variants of sex chromosomes (n=3), and suspected maternal sex chromosome imbalance (n=3). 53 had singleton pregnancies and three had dichorionic-diamniotic twin pregnancies. 58.9% had conventional combined Down syndrome screening; 15.2% of them were at high risk for trisomy 21. 33 (58.9%) of the patients opted for invasive diagnostic test: amniocentesis (n=29), chorionic villus sampling (n=3), and chorionic villus sampling followed by amniocentesis (n=1). Confirmatory cytogenetic test results (including postnatal results) were available in 35 cases. The overall positive predictive value of NIPT to detect fetal sex chromosome aneuploidies was 71.4%; the value was 42.9% for detecting 45, X, 100% for detecting 47,XXY, 80% for detecting 47,XXX, and 83.3% for detecting 47,XYY. False positive results were observed in three cases of confined placental mosaicism and three cases of vanishing twin pregnancies. Two women with 47,XXX and one woman with mosaic 45,X/46,XX were also incidentally discovered. Conclusion: Positive NIPT results for sex chromosome abnormalities can be caused by true fetal sex chromosome abnormalities, confined placental mosaicism/placental mosaicism, vanishing twins, and maternal X chromosome abnormalities. Multidisciplinary management can help prenatal counselling and genetic diagnosis. Follow-up confirmatory cytogenetic analysis prenatally and/or postnatally is useful to characterise the numeric or structural fetal sex chromosome abnormalities and their mosaic patterns, and can maximise the benefits of prenatal genetic screening in obtaining more genetic information to support pregnancy management and clinical care of affected unborn child. [ABSTRACT FROM AUTHOR]

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 β-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 (εγδβ)0-thalassemia [(εγδβ)0-thal], also inherited from the father. The fetus had a worsening anemic conditionin uteroand 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 (εγδβ)0-thal is usually mild, therefore, with accurate prenatal diagnosis this condition is salvageable byin uteroand early neonatal transfusions, preventing adverse pregnancy and neonatal outcomes. [ABSTRACT FROM AUTHOR]

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.

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., (© 2014 Wiley Periodicals, Inc.)

22q11.2 deletion syndrome (22q11.2DS) is a multi-systemic disorder with high phenotypic variability. Under-diagnosis in adults is common and recognition of facial dysmorphic features can be affected by age and ethnicity. This study aims to determine the prevalence of undiagnosed 22q11.2DS in adult Chinese patients with conotruncal anomalies and to delineate their facial dysmorphisms and extra-cardiac manifestations. We recruited consecutively 156 patients with conotruncal anomalies in an adult congenital heart disease (CHD) clinic in Hong Kong and screened for 22q11.2DS using fluorescence-PCR and fluorescence in-situ hybridization. Assessment for dysmorphic features was performed by a cardiologist at initial screening and then by a clinical geneticist upon result disclosure. Clinical photographs were taken and childhood photographs collected. Eighteen patients (11.5%) were diagnosed with 22q11.2DS, translating into 1 previously unrecognized diagnosis of 22q11.2DS in every 10 adult patients with conotruncal anomalies. While dysmorphic features were detected by our clinical geneticist in all patients, only two-thirds were considered dysmorphic by our cardiologist upon first assessment. Evolution of facial dysmorphic features was noted with age. Extra-cardiac manifestations included velopharyngeal incompetence or cleft palate (44%), hypocalcemia (39%), neurodevelopmental anomalies (33%), thrombocytopenia (28%), psychiatric disorders (17%), epilepsy (17%) and hearing loss (17%). We conclude that under-diagnosis of 22q11.2DS in Chinese adults with conotruncal defects is common and facial dysmorphic features may not be reliably recognized in the setting of adult CHD clinic, referral for genetic evaluation and molecular testing for 22q11.2DS should be offered to patients with conotruncal defects., (Copyright © 2014 Elsevier Masson SAS. All rights reserved.)

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., (Copyright © 2013 Elsevier Masson SAS. All rights reserved.)

We report on a male infant with de novo unbalanced t(5;15) translocation resulting in a 17.23 Mb deletion within 15q11.2-q14 and a 25.12 kb deletion in 5pter. The 15q11.2-q14 deletion encompassed the 15q11.2-q13 Prader-Willi syndrome (PWS) critical region and the recently described 15q13.3 microdeletion syndrome region while the 5pter deletion contained no RefSeq genes. From our literature review, patients with similar deletions in chromosome 15q exhibit expanded phenotype of severe developmental delay, protracted feeding problem, absent speech, central visual impairment, congenital malformations and epilepsy in addition to those typical of PWS. The patient reported herein had previously unreported anomalies of mega cisterna magna, horseshoe kidney and the rare neonatal interstitial lung disease known as pulmonary interstitial glycogenosis. Precise breakpoint delineation by microarray is useful in patients with atypical PWS deletions to guide investigation and prognostication., (Copyright © 2013 Wiley Periodicals, Inc.)

Background: Sublingual misoprostol has been shown to be effective in medical abortion. A prospective double-blinded placebo-controlled trial was done to compare the efficacy and side-effects of sublingual to oral misoprostol when used with mifepristone for medical abortion from 12 to 20 weeks gestation., Methods: A total of 120 women at 12-20 weeks of gestation were randomized to receive 200 mg oral mifepristone followed by either sublingual or oral misoprostol 400 mg every 3 h for a maximum of five doses 36-48 h later. The course of misoprostol was repeated if the woman did not abort within 24 h., Results: There was no significant difference (P = 0.43) in the success rate at 24 h [relative risk = 1.075; 95% confidence interval (CI): 0.94-1.19]. Abortion occurred in 91.4% in the sublingual group (95% CI: 81.0-96.7%) as compared to 85.0% (95% CI: 73.7-92.1%) in the oral group. The median induction-to-abortion interval was significantly shorter (P = 0.009) in the sublingual group (5.5 h) as compared to the oral group (7.5 h). The incidence of fever was higher in the sublingual group (P < 0.0001). The incidences of other side-effects were similar., Conclusion: Sublingual misoprostol, when combined with mifepristone, is effective for medical abortion in the second trimester. The induction-to-abortion interval is shorter when sublingual misoprostol is used when compared to oral misoprostol.