Prenatal diagnosis of mos46,X,del(Y)(q11.2)/45,X by cytogenetic and molecular studies with multiplex STR analysis

OBJECTIVES: To present the prenatal diagnosis of a fetus of mos46,X,del(Y)(q11.2)/45,X by cytogenetic and molecular analysis. CASE AND METHODS: A 35-year-old pregnant woman came to our hospital for amniocentesis, and fetal chromosomal aberrations with mos46,X, + mar/45,X were found. Fluorescence in situ hybridization revealed the existence of a Y centromere on the marker chromosome. Analysis with six pairs of short tandem repeat markers showed that the genomic DNA extracted from the uncultured amniotic fluid cells contained a deletion of Yq11.1-Yq11.2. Spermatogenesis loci of the Y chromosome were studied using four sets of multiplex PCR. The proximal two markers DYS271 and KALY were present and the other 16 distal markers were deleted. No deletion was noted in the Y chromosome of the father. RESULTS: Cytogenetic and molecular analyses revealed deletions of AZFb, d, and c regions on Yq11.2-Yqter in the fetal Y chromosome. Postmortem examination of the fetus showed a grossly normal male fetus with normal external genitalia and testes. CONCLUSION: The present report demonstrates that molecular analysis using polymorphic microsatellite markers and multiplex PCR is a useful complement to cytogenetic methods for the identification and the characterization of Y-chromosomal deletions.     

Mosaic 45,X/46, XX at amniocentesis with high-level mosaicism for 45,X in a pregnancy with a favorable fetal outcome and postnatal decrease of the 45,X cell line

ObjectiveWe present mosaic 45,X/46, XX at amniocentesis with high-level mosaicism for 45,X in a pregnancy with a favorable fetal outcome and postnatal decrease of the 45,X cell line.Case reportA 20-year-old, primigravid woman underwent amniocentesis at 17 weeks of gestation because of the non-invasive prenatal testing (NIPT) result of −4.82 Z score in sex chromosome at 12 weeks of gestation suggestive of Turner syndrome in the fetus. Amniocentesis revealed a karyotype of 45,X [18]/46,XX [15], and simultaneous multiplex ligation-dependent probe amplification (MLPA) on the DNA extracted from uncultured amniocytes showed mosaic Turner syndrome. Prenatal ultrasound and parental karyotypes were normal. She was referred for genetic counseling at 24 weeks of gestation, and continuing pregnancy was encouraged. At 39 weeks of gestation, a 2550-g phenotypically normal female baby was delivered. The karyotypes of cord blood, umbilical cord and placenta were 45,X [24]/46,XX [16], 45,X [23]/46,XX [17] and 45,X [28]/46,X,del(X) (q23)[12], respectively. When follow-up at age two months, the neonate was phenotypically normal in development. The peripheral blood had a karyotypes of 45,X [16]/46,XX [24]. Interphase fluorescence in situ hybridization (FISH) analysis on 103 buccal mucosal cells showed normal disomy X signals in all cells.ConclusionHigh-level mosaicism for 45,X in 45,X/46, XX at amniocentesis can be associated with a favorable fetal outcome, cytogenetic discrepancy in various tissues, and postnatal decrease of the 45,X cell line.     

Detection of mosaicism for 46,X,i(Y) (q10) in the blood lymphocytes in a phenotypically normal male neonate with prenatally detected 45,X/46, XY at amniocentesis and cytogenetic discrepancy in various tissues

ObjectiveWe present detection of mosaicism for 46,X,i(Y) (q10) in the blood lymphocytes in a phenotypically normal male neonate with prenatally detected 45,X/46, XY at amniocentesis and cytogenetic discrepancy in various tissues.Case reportA 35-year-old, gravida 2, para 1, woman underwent amniocentesis at 17 weeks of gestation because of advanced maternal age. Amniocentesis revealed a karyotype of 45,X [8]/46,XY [15]. Simultaneous array comparative genomic hybridization (aCGH) on uncultured amniocytes revealed the result of arr (Y) × 0–1 with 25.493-Mb mosaic deletion of chromosome Yp11.31-q11.23. Prenatal ultrasound findings were unremarkable. The fetus had normal male external genitalia on fetal ultrasound. Following genetic counseling, the pregnancy was carried to 38 weeks of gestation, and a phenotypically normal male baby was delivered without any abnormalities of the male external genitalia. The cord blood had a karyotypes of 46,X,i(Y) (q10)[8]/45,X[3]/46,XY [29], and placenta had a karyotypes of 45,X [25]/46,X,i(Y) (q10)[7]/46,XY [8]. When follow-up at age two months, the neonate was normal in development. The peripheral blood had a karyotypes of 46,X,i(Y) (q10)[8]/45,X[5]/46,XY [27]. Interphase fluorescence in situ hybridization (FISH) analysis on 101 buccal mucosal cells showed normal X and Y signals in 101/101 cells.ConclusionFetuses with 45,X/46, XY at amniocentesis can be associated with mosaicism for 46,X,i(Y) (q10) in the blood lymphocytes, cytogenetic discrepancy in various tissues and a favorable outcome.     

Sonographic genital ambiguity in a fetus due to a mosaic 45,X/46,X,idic(Y)(qter-p11.32::p11.32-qter) karyotype

Nowadays, improved ultrasound techniques enable the detection of more subtle congenital abnormalities at an earlier stage of fetal development. Current cytogenetic techniques can characterize a chromosomal abnormality in greater detail. These advancements in both diagnostic possibilities have helped to answer many questions but have also created new issues and dilemmas in counselling. This is illustrated by this case report of a 35-year-old woman, who presented at the end of the second trimester of her first pregnancy. Sonographic examination indicated an abnormal external genital in a male fetus. A differential diagnosis of hypospadia was made. During follow-up, an amniocentesis was performed, and this showed a 45,X/46,X,idic(Y)(qter-p11.32::p11.32-qter) karyotype as the cause of the sonographic findings. Cytogenetic characterization of the isodicentric Y chromosome and pre- and post-natal findings in the child are reported. Cases with a similar karyotype reported in the literature are reviewed.     

Gonadal dysgenesis and somatic stigmata in patients with 45,X/46,Xr(X) ring chromosome

Two cases of gonadal dysgenesis and stigmata of Turner's syndrome with ring chromosome X are described. Their features support the idea that ring chromosome X should be considered as a deletion in the genetic sense, affecting both the gonadal and statural determinants. Without knowing the cytogenetic findings, these patients are usually labeled as having Turner's syndrome. Furthermore, endocrine data and histologic examination of the gonads are indistinguishable from those of individuals with 45,X or 46XX gonadal dysgenesis.     

High-level mosaicism for 45,X in 45,X/46,X,idic(Y)(q11.2) at amniocentesis in a pregnancy with a favorable outcome and postnatal progressive decrease of the 45,X cell line

ObjectiveWe present prenatal diagnosis of high-level mosaicism for 45,X in 45,X/46,X,idic(Y)(q11.2) at amniocentesis in a pregnancy with a favorable outcome and postnatal progressive decrease of the 45,X cell line.Case reportA 36-year-old, gravida 4, para 3, woman underwent amniocentesis at 17 weeks of gestation because of advanced maternal age. Amniocentesis revealed a karyotype of 45,X[22]/46,X,idic(Y)(q11.2)[4]. Prenatal ultrasound was unremarkable, and the fetus had normal male external genitalia. Repeat amniocentesis was performed at 20 weeks of gestation, and the second amniocentesis revealed a karyotype of 45,X[24]/46,X,idic(Y)(q11.2)[3]. Simultaneous interphase fluorescence in situ hybridization (FISH) analysis on uncultured amniocytes revealed that 60% (62/103 cells) were Y-deleted cells. After genetic counseling, the parents decided to continue the pregnancy, and a 3020-g male baby was delivered with a body length of 52 cm, normal male genital organs and no phenotypic abnormalities. The karyotypes of cord blood, umbilical cord and placenta were 45,X[20]/46,X,idic(Y)(q11.2)[20], 45,X[31]/46,X,idic(Y)(q11.2)[9] and 45,X[40], respectively. At age one month, FISH analysis on urinary cells and buccal mucosal cells revealed 11.5% (7/61 cells) and 13.6% (16/118 cells), respectively for mosaicism for the Y-deleted cells. At age five month, the karyotype of peripheral blood was 45,X[9]/46,X,idic(Y)(q11.2)[31]. FISH analysis on buccal mucosal cells showed no abnormal Y-deleted cell (0/101 cells). At age 11 month, the karyotype of peripheral blood was 45,X[5]/46,X,idic(Y)(q11.2)[35]. FISH analysis on 102 buccal mucosal cells showed no abnormal signals. The infant was doing well with normal physical and psychomotor development.ConclusionHigh-level mosaicism for 45,X in 45,X/46,X,idic(Y)(q11.2) at amniocentesis can be associated with a favorable outcome and progressive decrease of the 45,X cell line.     

Prenatal diagnosis of 45,X/46,XY mosaicism--a review and update

A total of 54 cases with prenatal diagnosis of 45,X/46,XY mosaicism was reviewed. Of 47 cases with information on phenotypic outcome, 42 cases (89.4 per cent) were reported to be associated with a grossly normal male phenotype. Three cases (6.4 per cent) were diagnosed as having mixed gonadal dysgenesis with internal asymmetrical gonads. Two other cases were questionably abnormal. In 40 cases with successful cytogenetic confirmatory studies, the overall rate of cytogenetic confirmation of 45,X/46,XY from tissues derived from fetus/liveborn/placenta was 70.0 per cent. This review shows a major difference in the phenotypic outcome between postnatal diagnosis and prenatal diagnosis. Due to the ascertainment bias, almost all known patients with postnatal diagnosis of 45,X/46,XY mosaicism are phenotypically abnormal. Therefore, caution must be used in translating information derived from postnatal diagnosis to prenatal diagnosis. This review calls for collection of more data on 45,X/46,XY mosaicism diagnosed prenatally, more long-term follow-up of liveborn infants, and pathological studies of all abortuses. Emphasis is placed also on the importance of genetic counselling, ultrasound examination, and cytogenetic confirmation.     

Isodicentric Yp: prenatal diagnosis and outcome in 12 cases

OBJECTIVES: 1.To present the prenatal cytogenetic findings and postnatal outcome of 12 cases with an isodicentric chromosome composed of the short arm of the Y chromosome.2.To review the literature and provide recommendations for cytogenetic analysis and counseling. METHODS: Prenatal and postnatal cytogenetic data and clinical findings of isodicentric Yp ascertained in six institutions were gathered and reviewed. RESULTS: Nine of the twelve cases were referred for advanced maternal age (AMA), one of which was a twin pregnancy with one twin having an increased nuchal translucency measurement. The remaining cases were referred owing to a family history of hemophilia and an abnormal maternal serum screen, respectively. Nine of these pregnancies resulted in the birth of a normal-appearing male infant with subsequent normal growth and psychomotor development. Follow-up ranged from birth to 7 years. In two cases, the pregnancy was terminated and the fetuses showed male external genitalia. In the case ascertained because of an increased nuchal translucency measurement, the prenatal diagnosis of 45,X was made. At birth, there were ambiguous genitalia, and postnatal cytogenetic studies found an isodicentric Yp. In 11 of the 12 cases, mosaicism was present. CONCLUSION: Our cases show that the prenatal finding of an isodicentric Yp, with or without 45,X mosaicism, is compatible with normal male phenotype in most cases, particularly in the absence of other anomalies. To ensure accuracy in cytogenetic reporting and prenatal counseling, the identification of a structurally abnormal or small Y chromosome, either alone or in the presence of 45,X colonies, should be followed immediately by confirmatory molecular cytogenetic investigations as well as by ultrasound determination of the phenotypic sex of the fetus.     

Discrepancy between cytogenetic and FISH results on an amniotic fluid sample of 45,X/46,X,idic(Y)(p11)

The presence of abnormal ultrasound markers showing a thick nuchal fold with short middle phalanx of the fifth finger in an otherwise normal-appearing female fetus led to the sampling of amniotic fluid at 16 weeks gestation. Cytogenetic analysis with routine G-banding showed a 45,X karyotype in all 20 cells analysed from two flasks. However, fluorescent in situ hybridization on uncultured cells showed presence of a Y signal in 9 cells, 11 cells showing a single signal for the X. A cytogenetic analysis of the fetal blood at 23 weeks confirmed the presence of two cell lines, 45,X and 46,X, idic(Y)(p11). The couple opted to have the pregnancy terminated. However, the fetus was not available to carry out confirmatory tests.     

1例嵌合型45,X/46,X,r(Y)患者的遗传学分析

目的:应用细胞遗传学和分子生物学技术分析1例嵌合型45,X/46,X,r(Y)患者的核型。方法:应用常规染色体标本制备方法进行G-显带和C-显带;并应用CEPX(DXZ1,Xp11.1-q11.1,Spectrum Green,Vysis)探针、LSI SRY(Yp11.3,Spectrum Orange,Vysis)探针和CEP18(D18Z1,18p11.1-q11.1,Spectrum Aqua,Vysis)与患者的中期分裂相进行荧光原位杂交(fluorescence in situ hybridization,FISH);同时应用PCR技术对患者进行Y染色体微缺失检测。结果:结合G-显带、C-显带、FISH检测结果和Y染色体微缺失的检测结果,确定该患者核型为46,X,r(Y)(p11.3q12)[85]/45,X[15]。Yq11区生精基因微缺失检测未显示该患者存在缺失。结论:细胞遗传学检测结合FISH可以诊断复杂的染色体异常,为患者提供正确的遗传咨询和生育指导。     

Prenatal diagnosis of a case with tetrasomy 9p confirmed by cytogenetics,FISH, microarray analysis and review

ObjectiveTetrasomy 9p is a rare fetal condition. Cases are usually mosaic. Here, we present a non-mosaic tetrasomy 9p case with cytogenetic analysis, fluorescence in situ hybridization, microarray data, ultrasound findings, and phenotypic presentation.Case reportA pregnancy was referred to cytogenetic analysis because of increased nuchal translucency in prenatal ultrasound at 13 weeks of gestation. Prenatal laboratory analysis revealed an extra marker chromosome with a non-mosaic pattern. Ultrasonographic findings were unilateral cleft lip and palate, micrognathia, and atrioventricular septal defect at the 17th week; additionally, ventriculomegaly, left axis deviation of the fetal heart, and a single umbilical artery were determined at the 23rd week.ConclusionPhenotypic severity in non-mosaic tetrasomy 9p widely differs depending on the chromosomal content. We recommend performing appropriate genetic tests in those pregnancies with the suspicion of tetrasomy 9p, evaluating the mosaic state, and following those cases with detailed ultrasonographic examinations.     

High-level mosaicism for 45,X in 45,X/46,XX at amniocentesis in a pregnancy with a favorable outcome and postnatal progressive decrease of the 45,X cell line

ObjectiveWe present prenatal diagnosis of high-level mosaicism for 45,X in 45,X/46,XX at amniocentesis in a pregnancy with a favorable outcome and postnatal progressive decrease of the 45,X cell line.Case reportA 32-year-old, gravida 2, para 1, woman underwent amniocentesis at 17 weeks of gestation because of the abnormal first-trimester maternal serum screening result indicating a 1/34 risk for Down syndrome. Amniocentesis revealed a karyotype of 45,X[27]/46,XX[15]. Simultaneous array comparative genomic hybridization (aCGH) on uncultured amniocytes revealed 12% mosaicism for monosomy X. Prenatal ultrasound was normal. The pregnancy was carried to term, and a 2780-g phenotypically normal female baby was delivered. The cord blood had a karyotype of 45,X[12]/46,XX[28]. At age one month, the peripheral blood had a karyotype of 45,X[13]/46,XX[27]. Interphase fluorescence in situ hybridization (FISH) analysis on the buccal mucosal cells revealed 2% (2/102 cells) mosaicism for monosomy X, compared with 1% (1/100 cells) in the normal control. When follow-up at age one year, she was doing well with normal physical and psychomotor development. Her body weight was 9.9 Kg (50th – 85th centile), and her body height was 75 cm (50th – 85th centile). The peripheral blood had a karyotype of 45,X[4]/46,XY[36].ConclusionHigh-level mosaicism for 45,X in 45,X/46,XX at amniocentesis can be associated with a favorable outcome and postnatal progressive decrease of the 45,X cell line.     

Progressive increase of the mosaic level for 45,X in 45,X/46, XX at different amniocenteses and postnatal progressive decrease of the 45,X cell line in a mosaic 45,X/46, XX fetus with a favorable outcome

ObjectiveWe present progressive increase of the mosaic level for 45,X in 45,X/46, XX at different amniocenteses and postnatal progressive decrease of the 45,X cell line in a mosaic 45,X/46, XX fetus with a favorable outcome.Case reportA 35-year-old, primigravid woman underwent amniocentesis at 16 weeks of gestation because of the advanced maternal age. Amniocentesis revealed a karyotype of 45,X [6]/46,XX [14]. Among 20 colonies of cultured amniocytes, six colonies had a karyotype of 45,X, whereas the other 14 colonies had a karyotype of 46,XX. Simultaneous array comparative genomic hybridization (aCGH) on uncultured amniocytes revealed the result of arr [GRCh37] (X) × 1 [0.42] (1–22) × 2. Prenatal ultrasound findings were unremarkable. Repeat amniocentesis at 33 weeks of gestation revealed a karyotype of 45,X [13]/46,XX [7]. Among 20 colonies of cultured amniocytes, 13 colonies had a karyotype of 45,X, whereas the other seven colonies had a karyotype of 46,XX. Simultaneous interphase fluorescence in situ hybridization (FISH) analysis on 100 uncultured amniocytes revealed that 44 cells had monosomy X consistent with 44% mosaicism for 45,X, whereas the rest cells had disomy X. At 38 weeks of gestation, a 2675-g phenotypically normal female baby was delivered. The karyotypes of cord blood, umbilical cord and placenta were 45,X [12]/46,XX [28], 45,X [12]/46,XX [28] and 46,XX [40/40], respectively. When follow-up at age three months, the neonate was normal in development. The karyotypes of peripheral blood was 45,X [4]/46,XX [36], and interphase FISH analysis on 100 buccal mucosal cells showed monosomy X in 11 cells consistent with 11% mosaicism for 45,X, whereas the rest cells had disomy X.ConclusionProgressive increase of the mosaic level for 45,X in 45,X/46, XX at different amniocenteses can be associated with a favorable outcome and postnatal progressive decrease of the 45,X cell line.     

45,X/46,X,del(Yq) sex chromosome mosaicism--analysis of the phenotypic expression

Three female patients with Turner-syndrome (sexual infantilism, short stature and somatic Turner-stigmata) have been analysed cytogenetically by means of different banding techniques. A deletion of the distal heterochromatic band Yq12 of the Y chromosome was observed in a mosaic with a 45,X-cell line, i.e. the karyotype is 45,X/46,X,del(Y)(q12). In order to get information about the phenotypic expression of the 45,X/46,X,del(Yq) mosaicism all previously published cases have been reviewed. Comparing the phenotypes of all 45,X/46,X,del(Yq) mosaic cases three different phenotype categories of sexual development can be distinguished: female individuals with sexual infantilism and Turner-stigmata, individuals with ambiguous genitals, ranging from clitoris hypertrophy of female genitals to hypospadia of males, male individuals, who are infertile (azoospermic). A comparison of the appearance of external genitals with the status of gonads of all patients revealed an unequivocal relationship between the gonad status and the resulting phenotype category. Furthermore, the role of Y-chromosomal loci determining testicular differentiation (biological function of H-Y antigen) for male development has been emphasized. The effect of the 45,X-cell line on the expression of short stature and somatic Turner-stigmata is independent of sexual development. Considering the great phenotypic variability of the 45,X/46,X,del(Yq) mosaicism it seems impossible to deduce a definitive phenotype. This problem is acute in prenatal diagnosis especially.     

Perinatal cytogenetic discrepancy in a pregnancy with mosaic 45,X/46, XY at amniocentesis and a favorable outcome

ObjectiveWe present perinatal cytogenetic discrepancy in a pregnancy with mosaic 45,X/46, XY at amniocentesis and a favorable outcome.Case reportA 38-year-old, primigravid woman underwent amniocentesis at 17 weeks of gestation because of advanced maternal age. Amniocentesis revealed a karyotype of 45,X[2]/46,XY[6]. Level II ultrasound at 20 weeks of gestation was unremarkable, and the fetus had normal male external genitalia. Following genetic counseling, the woman decided to continue the pregnancy. At 39 weeks of gestation, a healthy male baby was delivered with a body weight of 3410 g and a body length of 54.5 cm. The male external genital organs were normal. The cord blood had a karyotype of 46, XY (40/40 cells). The umbilical cord had a karyotype of 45,X[1]/46,XY[39]. During follow-up at age one month, his body weight was 4.4 Kg (15th-50th centile), and his body length was 56 cm (50th-85th centile). The infant was doing well. Interphase fluorescence in situ hybridization analysis on 100 buccal mucosal cells revealed no abnormal Y-deletion cell, and all cells contained one Y signal.ConclusionPerinatal cytogenetic discrepancy may occur in the pregnancy with mosaic 45,X/46, XY at amniocentesis.     

Evaluation of sex chromosome aneuploidies in women with Turner's syndrome by G-banding and FISH. A serial case study

OBJECTIVE: To evaluate sex chromosome aneuploidies in patients with Turner's syndrome using two cytogenetic techniques. STUDY DESIGN: A sample of 35 women with a clinical suspicion of Turner syndrome was examined in the Hospital of Obstetrics and Gynecology, Instituto Mexicano del Seguro Social, Monterrey, Mexico. They were subjected to a conventional cytogenetic technique with G-banding and to fluorescence in situ hybridization (FISH) using a specific alpha satellite X chromosome (DXZ1) and specific alpha satellite Y chromosome (DYZ1). RESULTS: Using both techniques, 17 cases (48.57%) showed the same karyotype. Using FISH: (1) in 8 cases the presence of the Y chromosome was confirmed, (2) in 18 cases (51.43%) a new cell line was identified, (3) in 2 cases (5.71%) the derivative X was clarified, and (4) in 3 cases (8.57%) the origin of the chromosome markers (1 of X chromosome and 2 of Y chromosome) was delineated. FISH highlighted the differences between the initial diagnosis, based on G-banding, and the final diagnosis, determined by specific probes for the X and Y chromosomes. CONCLUSION: FISH is a useful tool in the detection of low-frequency cell lines and identification of the nature and origin of derivative chromosomes and unknown chromosome markers that have important implications for the treatment of patients with Turner's syndrome.     

Prenatal diagnosis of a 45,X male with a SRY-bearing chromosome 21

Male phenotype associated with a 45,X karyotype is an infrequent finding. We present a case diagnosed prenatally on amniocentesis performed for maternal age. The male phenotype was associated with a translocation of a distal part of Yp including the pseudoautosomal SHOX gene and SRY gene on the short arm of a chromosome 21. By DNA analysis we could show that the X chromosome was of maternal origin and that the breakpoint was in interval 3 of the Y chromosome. Mechanisms and genetic counselling are discussed based on a review of published cases of 45,X and XX males.     

Two pregnancies and the loss of the 46,XX cell line in a 45,X/46,XX Turner mosaic patient

Two successful pregnancies in a patient with a 45,X karyotype are reported. Twelve pregnancies have been reported in 9 monosomy X patients and 57 pregnancies in 24 patients with both a 45,X and a 46,XX cell line. The patient reported here was diagnosed at 10 years of age as a Turner mosaic (45,X/46,XX), but showed no evidence of a normal cell line in any of the four tissues analyzed 15 years later. The difficulty in detecting mosaicism as well as the stability of autosomal and sex chromosomal mosaicism are discussed. An argument is made for early cytogenetic evaluation, utilizing multiple tissues, and analyzing an adequate number of cells.