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.

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.

Rapid aneuploidy testing (knowing less) versus traditional karyotyping (knowing more) for advanced maternal age: what would be missed, who should decide?

OBJECTIVES: The application of rapid aneuploidy testing as a stand-alone approach in prenatal diagnosis is much debated. The major criticism of this targeted approach is that it will not detect other chromosomal abnormalities that will be picked up by traditional karyotyping. This study aimed to study the nature of such chromosomal abnormalities and whether parents would choose to terminate affected pregnancies. DESIGN: Retrospective study on a cytogenetic database. SETTING: Eight public hospitals in Hong Kong. PARTICIPANTS: The karyotype results of 19 517 amniotic fluid cultures performed for advanced maternal age (>or=35 years) from 1997 to 2002 were classified according to whether they were detectable by rapid aneuploidy testing. The outcomes of pregnancies with abnormal karyotypes were reviewed from patient records. RESULTS: In all, 333 (1.7%) amniotic fluid cultures yielded abnormal karyotypes; 175 (52.6%) of these were detected by rapid aneuploidy testing, and included trisomy 21 (n=94, 28.2%), trisomy 18 or 13 (n=21, 6.3%), and sex chromosome abnormalities (n=60, 18.0%). The other 158 (47.4%) chromosomal abnormalities were not detectable by rapid aneuploidy testing, of which 63 (18.9%) were regarded to be of potential clinical significance and 95 (28.5%) of no clinical significance. Pregnancy outcomes in 327/333 (98.2%) of these patients were retrieved. In total, 143 (42.9%) of these pregnancies were terminated: 93/94 (98.9%) for trisomy 21, 20/21 (95.2%) for trisomy 18 or 13, 19/60 (31.7%) for sex chromosome abnormalities, and 11/63 (17.5%) for other chromosomal abnormalities with potential clinical significance. There were no terminations in the 95 pregnancies in which karyotyping results were regarded to be of no clinical significance. CONCLUSIONS: 'Knowing less' by the rapid aneuploidy stand-alone testing could miss about half of all chromosomal abnormalities detectable by amniocentesis performed for advanced maternal age. Findings from two fifths of the latter were of potential clinical significance, and the parents chose to terminate one out of six of the corresponding pregnancies. If both techniques are available, parents could have enhanced autonomy to choose.

Prenatal detection of a de novo Yqh-acrocentric translocation.

OBJECTIVES: To identify the extra chromosomal material on 46,XX,21p+ for prenatal diagnosis. DESIGN AND METHODS: Conventional cytogenetic studies using GTG (G bands by trypsin using Giemsa) and CBG (C bands by barium hydroxide using Giemsa) techniques were performed on chromosomes at metaphase obtained from cultured amniocytes and parental blood lymphocytes. Molecular cytogenetic techniques, QF-PCR (quantitative fluorescent polymerase chain reaction), FISH (fluorescent in-situ hybridization), and DA-DAPI (Distamycin A and 4,6-diamino-2-phenylindole) staining, were then used to clarify the extra material present on fetal chromosome 21 p. RESULTS: The extra material on fetal chromosome 21 p has originated from Yqh, most likely at PAR2 (the secondary pseudoautosomal region). The karyotype should be 46,XX,der(21)t(Y;21)(q12;p13)de novo.ish der(21)t(Y;21)(q12;p13) (EST Cdy16c07+). CONCLUSION: This case demonstrates the usefulness of molecular techniques in the investigation of rare chromosomal rearrangements.