Bom Yi Lee

Molecular and Clinical Characteristics of 26 Cases with Structural Y Chromosome Aberrations

Structural abnormalities include various types of translocations, inversions, deletions, duplications and isochromosomes. Structural abnormalities of the Y chromosome are estimated to affect less than 1% of the newborn male population and are particularly hazardous for male reproductive function. The objective of this study was to characterize a group of patients with structural abnormalities of the Y chromosome. All patients who visited our laboratory between 2007 and 2010 underwent cytogenetic investigations. Among these, we detected 26 patients with structural abnormalities of the Y chromosome. To confirm the structural Y chromosome alterations, we used special bandings, FISH and multiplex PCR to detect Y chromosome microdeletions. Of the 26 patients presented here, 11 had an isodicentric Y chromosome, 7 had an inversion, 3 had a translocation, 2 had a derivative, 2 had a Yqs and 1 had a deletion. Sixteen were diagnosed with azoospermia, 8 as normal fertile males and 1 as a man who was unable to donate semen due to mental retardation. One of the patients having 45,X/46,X,idic(Y) was reported to be phenotypically female with primary amenorrhea and without uterus. Deletions of the AZFbc region were correlated with the sperm concentration (p < 0.05), but no correlation with the levels of FSH, LH, testosterone, prolactin and estradiol were found. The present report shows that the precise identification of structural Y chromosome aberrations may be clinically important for genetic counseling and assisted reproductive technology treatment.

Rapid Prenatal Diagnosis of Down Syndrome Using Quantitative Fluorescent PCR in Uncultured Amniocytes

Rapid prenatal diagnosis of common chromosome aneuploidies have been successful through quantitative fluoresent PCR (QF-PCR) assays and small tandem repeat (STR) markers. The purpose of our study was to investigate the clinical feasibility for rapid prenatal detection of Down syndrome using the quantitative fluorescent PCR in uncultured amniocytes. DNA was extracted from uncultured amniotic fluid of normal karyotype (n=200) and of Down syndrome (n=21). It was amplified using QF-PCR with four STR markers located on chromosome 21. Among normal samples, the ranges of diallelic peaks for at least one STR marker were 1.0-1.3 for D21S11, 1.0-1.4 for D21S1411 and 1.0-1.5 for D21S1270. Down syndrome samples showed trisomic triallelic patterns or trisomic diallelic patterns. The sensitivity, specificity, and efficiency of the assay for detecting Down syndrome were 95.4%, 100%, and 99.5%, respectively. Rapid prenatal diagnosis of Down syndrome using QF-PCR is a reliable technique that aids clinical management of pregnancy.

Non-invasive detection of fetal trisomy 21 using fetal epigenetic biomarkers with a high CpG density.

Abstract Background: Non-invasive prenatal test of trisomy 21 (T21) is being researched using fetal specific epigenetic biomarkers present in maternal plasma. We applied a methyl-CpG binding domain-based protein (MBD) method based on epigenetic characteristics of fetal specific-methylated regions with a high CpG density in HLCS on chromosome 21 and RASSF1A on chromosome 3 for the non-invasive detection of fetal T21 and estimated the diagnostic accuracy of the method. Methods: A nested case-control study was conducted with maternal plasma collected from 50 pregnant women carrying 40 normal and 10 T21 fetuses. A MBD method was used for enrichment of methylated DNA regions in maternal plasma. The levels of methylated HLCS (M-HLCS) and methylated RASSF1A (M-RASSF1A) were simultaneously measured by multiplex qPCR. Results: Levels of M-HLCS and M-RASSF1A were obtained in all cases. Levels were not different according to fetal gender (p>0.05 in both). The level of M-HLCS was significantly increased in women with a T21 fetus compared with controls (p<0.001). The level of M-RASSF1A was not different between two groups (p>0.05). In non-invasive fetal T21 detection, the specificity of M-HLCS level and the epigenetic-epigenetic ratio (EER) using M-HLCS and M-RASSF1A levels were 82.5% and 92.5%, respectively, at 90.0% sensitivity. Conclusions: Our findings suggest that the EER may be useful as a potential biomarker for the non-invasive detection of fetal T21, regardless of fetal gender. The MBD method can be used as an effective tool in the detection of methylated fetal specific markers with a high CpG density in maternal plasma.

Unusual Maternal Uniparental Isodisomic X Chromosome Mosaicism with Asymmetric Y Chromosomal Rearrangement

Infertile men with azoospermia commonly have associated microdeletions in the azoospermia factor (AZF) region of the Y chromosome, sex chromosome mosaicism, or sex chromosome rearrangements. In this study, we describe an unusual 46,XX and 45,X mosaicism with a rare Y chromosome rearrangement in a phenotypically normal male patient. The patients karyotype was 46,XX[50]/45,X[25]/46,X,der(Y)(pter→q11.222::p11.2→pter)[25]. The derivative Y chromosome had a deletion at Yq11.222 and was duplicated at Yp11.2. Two copies of the SRY gene were confirmed by fluorescence in situ hybridization analysis, and complete deletion of the AZFb and AZFc regions was shown by multiplex-PCR for microdeletion analysis. Both X chromosomes of the predominant mosaic cell line (46,XX) were isodisomic and derived from the maternal gamete, as determined by examination of short tandem repeat markers. We postulate that the derivative Y chromosome might have been generated during paternal meiosis or early embryogenesis. Also, we suggest that the very rare mosaicism of isodisomic X chromosomes might be formed during maternal meiosis II or during postzygotic division derived from the 46,X,der(Y)/ 45,X lineage because of the instability of the derivative Y chromosome. To our knowledge, this is the first confirmatory study to verify the origin of a sex chromosome mosaicism with a Y chromosome rearrangement.

Determination of the carrier frequencies of selected GJB2 mutations in the Korean population.

Abstract Objective: Mutations in the GJB2 gene are a major cause of hereditary hearing loss. However, only a few studies have investigated carrier frequencies of GJB2 mutations in the general population. The aim of this study was to estimate the carrier frequencies of three GJB2 mutations, including 235delC, V37I, and G45E, in the general Korean population. Design: A standard questionnaire of self-reported hearing loss was used to identify and recruit subjects. Screening for three mutations was performed using an allele-specific polymerase chain reaction (PCR), PCR-restriction fragment length polymorphism, and direct DNA sequencing. Study sample: A total of 1256 unrelated healthy individuals were analysed in the present study. Results: Of the 1256 individuals, 24 had GJB2 mutations; 11 were found to be heterozygous for 235delC, 11 were heterozygous and one was homozygous for V37I, and one was heterozygous for G45E. One individual had a compound heterozygous mutation of 235delC/V37I. The allele frequencies of 235delC, V37I, and G45E mutations were 0.44%, 0.52%, and 0.04%, respectively. The carrier frequency of either the 235delC or V37I mutation was estimated to be 0.88% with 95% binomial CI, 0.44–1.56. Conclusions: These results will facilitate diagnosis of, and genetic counseling for, hearing loss in Koreans. Sumario Objetivo: Las mutaciones del gene GJB2 son una causa muy importante de pérdidas auditivas hereditarias. No obstante, solamente pocos estudios han investigado las frecuencias portadoras de las mutaciones del GJB2 en la población general. El objetivo de este estudio fue estimar las frecuencias portadoras de tres mutaciones del GJB2, incluyendo la 235delC, V37I y G45E, en la población general de Corea. Diseño: Se utilizó un cuestionario estándar de pérdida auditiva auto-reportada para identificar y reclutar sujetos. El tamiz de las tres mutaciones se realizó usando una reacción en cadena de la polimerasa alelo-específica (PCR), el polimorfismo de los fragmentos de restricción PCR y la secuenciación directa de DNA. Muestra de estudio: Se analizaron en este estudio 1,256 individuos sanos, no relacionados, (sanos en este estudio). Resultados: De los 1,256 individuos, 24 tenían mutaciones del GJB2; 11 se encontraron como heterocigóticos para el 235delC, 11 fueron heterocig ticos y uno fue homocigótico para V37I y uno fue heterocigótico para G45E. Un individuo tenía una mutación heterocigótica compuesta del 235delC/V37I. Las frecuencias de las mutaciones del alelo de 235delC, V37I, y G45E fueron del 0.44%, 0.52%, y 0.04%, respectivamente. La frecuencia portadora de las mutaciones tanto del 235delC como del V37I se estimó en 0.88%, con CI binomial del 95% de 0.44-1.56. Conclusiones: Estos resultados facilitarán el diagnóstico y el asesoramiento genético en casos de pérdida auditiva en la población de Corea.

Paracentric Inversions Found in Prenatal Diagnosis

Inversions are balanced rearrangements of chromosomes, and the vast majority of paracentric inversions seem to be harmless. The risk of having a phenotypically abnormal child for carriers of paracentric inversions due to the production of unbalanced gametes resulting from recombination during meiotic crossover has been thought to be low. However, a few cases of abnormal offspring due to classic recombination of inversion have been described. Spontaneous abortion, infertility, and mental retardation and/or congenital malformation of offspring have also been reported among paracentric inversion carriers. In this study, we characterized paracentric inversions identified in 10 cases observed in prenatal diagnosis at our center during a five-year period. Paracentric Inversions Found in Prenatal Diagnosis

Preeclampsia is associated with an elevation of plasma sMet concentrations in the second trimester.

Abstract Objective: The aim of this study was to investigate the association between anti-angiogenic factor soluble c-Met (sMet) concentrations in maternal plasma and the risk of preeclampsia. Methods: The pregnant women included in this study (1) had subsequent preeclampsia (n = 52) and were compared to normal controls (n = 104) at the time of amniocentesis (15–20 weeks); and (2) had preeclampsia (n = 63) and were compared to normal controls (n = 112) at the time of diagnosis of preeclampsia (29–40 weeks). sMet concentrations were measured by ELISA. Non-parametric statistics were used for analysis. Results: Maternal plasma sMet concentrations were significantly higher in both women with subsequent preeclampsia (median: 1372.7 ng/ml versus 1100.5 ng/ml; p = 0.036) and women with preeclampsia (median: 1651.9 ng/ml versus 1364.7 ng/ml; p < 0.001) than in the controls. After adjusting for potential confounding factors, the risks of developing preeclampsia were as follows: adjusted odds ratio 2.5 (95% confidence interval, 1.2–5.2; p = 0.016) for second trimester sMet concentration with a cut-off value of 1223.5 ng/ml and 4.4 (95% confidence interval, 2.2–9.1; p < 0.001) for third trimester sMet concentration with a cut-off value of 1460.3 ng/ml. Conclusion: Elevated maternal plasma sMet concentrations were independently associated with the increased risk of preeclampsia.

A Prenatal Case of Paracentric Inversion of Chromosome 18, inv(18)(q21.1q22)

an abnormal child. Madan K et al reported out of 50 cases of paracentric inversion, 34 were familial with one or more pheno typically normal carriers in the family. Most paracentric inversions are likely to be harmless, but due to breakpoint variation or recombination, various clinical phenotypes are seen. Paracentric inversions can cause infertility, recurrent spontaneous abortion, 9) or abnormal children which includes mental retardation or microcephaly. We report a prenatally detected case of familial chromosome 18 paracentric inversion with normal clinical features (Fig. 1).

Clinical, Hormonal, and Genetic Evaluation of Idiopathic Nonobstructive Azoospermia and Klinefelter Syndrome Patients

To investigate the clinical, hormonal, and genetic factors in infertile men with idiopathic nonobstructive azoospermia (NOA) or azoospermic Klinefelter syndrome (KFS), a total of 556 and 96 patients, respectively, were included in this study. All patient samples were analyzed cytogenetically. Serum reproductive hormone levels were measured. Microdeletions in the azoospermia factor (AZF) region of the Y chromosome were detected by multiplex PCR using 16 specific sequence-tagged sites. FSH and LH levels in both NOA and KFS patients were significantly higher than the normal range, and the testosterone level in KFS patients was significantly lower. Ninety-two (95.8%) of the KFS patients showed non-mosaic 47,XXY karyotypes and 47,XXY,inv(9)(p11.1q13); the other KFS patients had mosaic karyotypes of 47,XXY/46,XY, 47,XXY/46,XX, and 47,XXY/48,XXXY/46,XX. Among the 556 idiopathic NOA patients with normal karyotypes, 67 (12.05%) had microdeletions in the AZF region of the Y chromosome. Microdeletions were most frequently detected in the AZFc region, followed by AZFa, AZFb, AZFbc, and partial AZFc deletions. However, Y chromosome microdeletions were not found in any of the azoospermic KFS patients. In view of the hormonal and genetic abnormalities in infertile men with idiopathic NOA and with azoospermic KFS, genetic testing for karyotype, Y chromosome microdeletions, and hormonal parameters is advocated.

Three cases of rare SRY-negative 46,XX testicular disorder of sexual development with complete masculinization and a review of the literature

Müllerian inhibiting factor that induces regression of Müllerian ducts that in females would differentiate into the uterus. These processes for sex determination do not occur in females in the absence of SRY. Sex differentiation related genes such as SOX9, FGF9, DAX1, WT1, RSPO1, and SOX10, which are located on either autosomes or the X chromosome, may have a role in gonad development and function. These genes were studied in Three cases of rare SRY-negative 46,XX testicular disorder of sexual development with complete masculinization and a review of the literature