Chimerism and multiple numerical chromosome imbalances in a spontaneously aborted fetus

We report on a case of chimerism and multiple abnormalities of chromosomes 21, Xand Yin spontaneous abortion specimen. To the best our knowledge the present case is the first documented chimera in a spontaneously aborted fetus. The application of interphase fluorescence in situ hybridization (FISH) using chromosome enumeration and site-specific DNA probes showed trisomy X in 92 nuclei (23 %), tetrasomy X in 100 nuclei (25 %), pentasomy of chromosome X in 40 nuclei (10 %), XXY in 36 nuclei (9 %), XXXXXXYY in 12 nuclei (3 %), XXXXXYYYYY in 8 nuclei (2 %), trisomy 21 and female chromosome complement in 40 nuclei (10 %), normal female chromosome complement in 72 nuclei (18 %) out of 400 nuclei scored. Our experience indicates that the frequency of chimerism coupled with multiple chromosome abnormalities should be no less than 1 : 400 among spontaneous abortions. The difficulties of chimerism identification in fetal tissues are discussed.     

The mechanism of secondary nondisjunction in Drosophila melanogaster females

Bridges (1916) observed that X chromosome nondisjunction was much more frequent in XXY females than it was in genetically normal XX females. In addition, virtually all cases of X nondisjunction in XXY females were due to XX <--> Y segregational events in oocytes in which the two X chromosomes had failed to undergo crossing over. He referred to these XX <--> Y segregation events as "secondary nondisjunction." Cooper (1948) proposed that secondary nondisjunction results from the formation of an X-Y-X trivalent, such that the Y chromosome directs the segregation of two achiasmate X chromosomes to opposite poles on the first meiotic spindle. Using in situ hybridization to X and YL chromosomal satellite sequences, we demonstrate that XX <--> Y segregations are indeed presaged by physical associations of the X and Y chromosomal heterochromatin. The physical colocalization of the three sex chromosomes is observed in virtually all oocytes in early prophase and maintained at high frequency until midprophase in all genotypes examined. Although these XXY associations are usually dissolved by late prophase in oocytes that undergo X chromosomal crossing over, they are maintained throughout prophase in oocytes with nonexchange X chromosomes. The persistence of such XXY associations in the absence of exchange presumably facilitates the segregation of the two X chromosomes and the Y chromosome to opposite poles on the developing meiotic spindle. Moreover, the observation that XXY pairings are dissolved at the end of pachytene in oocytes that do undergo X chromosomal crossing over demonstrates that exchanges can alter heterochromatic (and thus presumably centromeric) associations during meiotic prophase.     

Distribution of α1-(PI) phenotypes in chromosome abnormalities

Summary PI phenotypes (including subtypes) were determined for 168 individuals with chromosomal abnormalities ascertained in Adelaide. These included patients with mosaicism, trisomy 21, trisomy 13, trisomy 18, and various sex chromosome aberrations (45,X, 47,XXX, 47,XXY, 47,XYY, and 48,XXXY). Data did not support an existing proposition that mildly deficient PI phenotypes predispose to abnormal chromosome segregation during mitosis or meiosis. Phenotypic distributions of each group were statistically similar to control populations of cord bloods and bloods donors.     

Incidence of major chromosome aberrations in 12,319 newborn infants in Tokyo

Summary In order to ascertain the frequency of chromosome aberrations among newborn infants in Japan, a chromosome survey of a large number of newborn infants is in progress. A consecutive series of 12,319 newborn babies, 6382 male and 5937 female, have been screened for clinical manifestations of autosomal aberrations and for sex chromatin and sex chromosome aberrations. Chromosome studies were carried out on 694 infants with suspected chromosome aberrations. The clinically abnormal infants were screened by conventional staining, and banding techniques have been used in the part of the study performed since 1974. Of the clincally abnormal infants, 25 had abnormal karyotypes, including two males with a 47,XXY complement, one female with a 45,X complement, three male infants with a 47,XYY complement, two with trisomy 13 syndrome, three with trisomy 18 (including one case of mosaicism), eleven with Down's syndrome (including one case of mosaicism), one with B5p partial trisomy, one with cri-du-chat syndrome, and one with Y/D translocation. The overall results are comparable to those of previous population cytogenetic studies only in the autosomal trisomies and sex chromosome abnormalities and in that the observed frequencies were comparable to those found in studies in Caucasians.To whom offprint requests should be sent     

47,XXY males: sex chromosomes and tooth size.

Permanent tooth crowns of 47,XXY males were found to be generally larger than those of control males and females and their first-degree male and female relatives. These results suggest that tooth-size increase in 47,XXY males is due to a direct genetic effect and support the concept of the presence of a specific growth gene (or genes) in the human X and Y chromosomes. The effect of this gene (or genes) seems to be the promotion of tooth growth, and the Y chromosome is more effective than the X chromosome in this respect.     

Different chromosome Y abnormalities in Turner syndrome.

A 17-year-old phenotypically female girl was referred for evaluation because of short stature and primary amenorrhea. Cytogenetic analysis showed a mosaic 46,XY/45,X/47,XYY/46,X,idic(Yq)/47,XY,idic(Yq)/48,XXY,idic(Yq)/46,X,t(C;Y) karyotype. Conventional cytogenetic results were supplemented with fluorescence in situ hybridization (FISH) techniques to ensure a better characterization of abnormalities. By using FISH, a supernumerary marker chromosome derived from chromosome Y which could not be detected by conventional cytogenetics was revealed. Furthermore, additional abnormalities and their frequencies were highlighted by the application of DNA probes specific for X and Y chromosomes. Thus, FISH proved useful in determining low frequency cell lines which would need analysis of a large number of good quality metaphase spreads by conventional cytogenetic techniques: it helped in identifying the nature and the origin of unknown markers and rearrangements which have important implication in sexual differentiation and development of gonadal tumours.     

Cytogenetics and fluorescence in situ hybridization assessment of sex-chromosome mosaicism in Klinefelter's syndrome

A retrospective study was carried out in 152 infertile men to determine the prevalence of sex chromosome abnormalities among non-obstructive azoospermic and severe oligospermic men (n = 51) and to evaluate the feasibility of fluorescence in situ hybridization (FISH) techniques to assess mosaicism in Klinefelter's patients in comparison with conventional cytogenetics. Cytogenetic analysis were performed for 51 infertile men and among 14 chromosomal abnormalities found, nine were compatible with Klinefelter's syndrome. FISH staining with a CEP X/CEP Y probes were performed for Klinefelter's patients and for five of them; testes were biopsied for histopathologic examination. Six Klinefelter's patients showed a non-mosaic 47,XXY and three showed a 47,XXY/46,XY mosaic by G or R banding analysis of 20 cells with a ratio of 17%, 20% and 33%, respectively. FISH analysis confirmed mosaicism in only one patient (the first) in whom a third cells population was found. There was no relationship between the ratios of mosaicism by banding and FISH analysis. Conventional histopathologic findings in five non-mosaic Klinefelter's patients confirm the diagnosis of Sertoli Only Cells syndrome. FISH is recommended in Klinefelter's syndrome to define exactly the cytogenetic statute as mosaic or non-mosaic and then discussing prognosis and decision regarding fertility counseling.     

Cytogenetic analysis reveals clonal proliferation of smooth muscle cells in atherosclerotic plaques

Summary Cytogenetic analysis of primary cell cultures from human atherosclerotic fibrous plaques revealed clonal chromosome abnormalities in 13 of the 18 cases studied. Loss of the Y chromosome and del(13)(q14) were present as single clonal abnormalities in eight cases; in five cases separate clones were found involving loss of the Y and a XXY karyotype, trisomy 10 and 18, loss of the Y and trisomy 7. A variety of single numerical and structural abnormalities were present in all but two of the 18 cases. Immunocytochemical studies were performed on cells from the same cultures used for cytogenetic analysis using monoclonal antibodies to human leucocyte common antigen, to human vimentin and to muscle actin. The immunoreactivity was positive for actin in 70–80% of the cells; 100% of the cells were positive for vimentin and all cells were ALC negative. These results indicated that the chromosomal abnormalities are present in the smooth muscle cells of the plaque. The hypothesis is proposed that the proliferation leading to the atherosclerotic lesion may primarily represent a hyperplastic response to mechanical and biological injuries and that this reactive proliferation is, in turn, associated with a tendency to chromosome instability.     

Chromosome studies in 500 induced abortions.

A survey of the chromosome constitution in 500 induced abortions (5-12 menstrual weeks) was undertaken over a period of 1 1/2 years. There were 34 cases (6.8%) of gross chromosome anomalies: 2 cases of trisomy A; 5 of trisomy C (including XXX and XXY); 1 of mosaic trisomy C; 4 of trisomy D; 2 of trisomy E; 2 of trisomy G; 1 of double trisomy E and G; 1 of XYY; 4 of monosmy C (including XO); 2 of mosaic monosomy C; 1 of mosaicism of ring D chromosome; 1 of extra small metacentric chromosome; 3 of triploidy (including triploidy with double trisomy C and G); and 5 of tetraploidy and its mosaicism. An increased risk for the occurrence of trisomic anomalies was found with advancing age of the mothers. In contrast, the production of monosomies was not age-related. Trisomies were the most common type of anomalies and were found almost at random, regardless of the characteristics of chromosomes. Neither satellited nor small chromosomes were predominantly involved in the formation of chromosome anomalies.     

Spontaneous interchanges in females of Drosophila melanogaster

Summary Herein is described an attempts to establish chromosome pairing-interchange relationships in Drosophila melanogaster female. For this purpose, the formation of half-translocations was studied in XXY and XX females bearing compounds of the second pair of autosomes. With respect to XXY females, it was expected that the free Y chromosome would pair with these compounds and that half-translocations involving 2L would arise. In as much as compound chromosomes in XX females had no partner for pairing, the formation of half-translocations involving 2L was not expected.Half-translocations were registered in the F₁ from crosses of XX and XXY females to b j pr cn/T(Y;2)C males. The cross was designed to permit the detection of very rarely occurring non-homologue interchanges.Offspring number was 335 in XX females and 550 in XXY females. The majority of offspring consisted of individuals arisen from the spontaneous restitution of compounds and the formation of 2n egg cells. Based on phenotype, the offspring of XX females contained 4 individuals with half-translocations involving 2L; there were 48 such flies among the offspring of XXY females. As confirmed by progeny analysis, 38 half-translocations occurred in XXY females and none in XX females. Of the 31 spontaneous interchanges in XXY females 28 were recorded between the Y and the left compound, one between the Y and the right compound, and one between the X and the left compound. Non-homologue interchanges were of oogonial origin judging by the fact that individuals with half-translocations arose in clusters. Unlike Y — left compound interchanges, the interchanges between autosomal compounds seem to be of meiotic origin.     

Replication pattern of the X and Y chromosomes in partially synchronized human lymphocyte cultures

The replication pattern of the X and Y chromosomes at the beginning of the synthetic phase was studied in human lymphocyte cultures partially synchronized by the addition of 5-fluoro-2-deoxyuridine (FUdR). The data were evaluated statistically by an analysis of the distribution of silver grain counts over the X and Y chromosomes. —In cells from normal females, one of the X chromosomes began replication later than any other chromosomes of the complement. The short arm of the late replicating X chromosome started replication earlier than the long arm. The telomeric region of the short arm was a preferential site of DNA synthesis at the beginning of replication. —In partially synchronized lymphocyte cultures from a patient with the XXY syndrome, the Y chromosome started replication together with the late replicating X chromosome. The Y chromosome most frequently replicated synchronously with the short arm of the X. The centromeric region of the Y chromosome initiated synthesis before the telomeric region and appeared to replicate synchronously with the telomeric region of the short arm of the X. These findings are discussed with reference to the pairing of the X and Y chromosomes at meiosis.Supported in part by the National Institute of Health Research Grant HD-01979 and National Foundation Birth Defects Research Grant CRCS-40. Dr. Knight was a predoctoral fellow under National Institute of Health Training Program HD-00049-09.     

Interphase cytogenetics reveals somatic pairing of chromosome 17 centromeres in normal human brain tissue, but no trisomy 7 or sex-chromosome loss

Nuclei isolated from normal human brain tissue, collected from six autopsies, were hybridized with a panel of nine satellite DNA probes specific for the centromeric regions of chromosomes 1, 6, 7, 10, 11, 17, 18, and the X and Y chromosomes. The results did not confirm the recently reported trisomy 7 and loss of sex chromosomes observed in metaphases obtained from normal brain tissue after short-term cultures; however, cells of all six brains displayed somatic pairing of the chromosome 17 centromeres in approximately 50% of the nuclei.     

Coexistence of inverted Y, chromosome 15p+ and abnormal phenotype.

In this study, we report conventional and molecular cytogenetic studies in a patient with multiple anomalies who is a carrier of a pericentric inversion on chromosome Y and a chromosome 15p+. His parents were phenotypically normal. The father is a carrier of a pericentric inversion of chromosome Y, and the mother carries a large chromosome 15p+ variant. The inverted Y chromosome was demonstrated by GTG- and CBG-banding, and DAPI-staining. The presence of extra chromosomal material on the chromosome 15p, that was C-band and DAPI positive, was demonstrated by trypsin G-banding. This suggests that the extra chromosomal material contained repetitive DNA sequences. NOR-staining indicated the presence a nuclear organizer region at the junction of the chromosome 15p+ material. Fluorescence in situ hybridization (FISH), with chromosome X and Y painting probes, alpha- and classic-satellite probes specific for chromosome Y, alpha- and beta-satellite III probes for chromosome 15 were used to elucidate the nature of both the inverted Y chromosome and chromosome 15p+. The result with chromosome X and Y painting probes, alpha-satellite, classic-satellite, and DYS59 probes specific for chromosome Y revealed the rearrangement of the Y chromosome was an inv(Y)(p11.2q11.22 or q11.23). FISH with alpha-satellite and beta-satellite III probes for chromosome 15 demonstrated that the extra chromosomal material on the chromosome 15 probably represents beta-satellite III sequences. The possible roles of the simultaneous occurrence of an inverted Y and the amplified DNA sequence on chromosome 15p in the abnormal phenotype of the proband are discussed.     

A 48,XXY,+21 Down syndrome patient with additional paternal X and maternal 21

Summary The origin of meiotic nondisjunction of the extra chromosomes X and 21 was studied in a patient with the karyotype 48,XXY,+21 using DNA polymorphisms. The extra chromosome X was the result of paternal first meiotic nondisjunction of X and Y. The extra chromosome 21 was derived from the mother. The meiotic error in the mother most probably occurred in meiosis II. Thus, this is a combination caused by the chance occurrence of two independent events.     

Dependence on genic balance for synaptonemal complex formation in Drosophila melanogaster

Electron microscopic examination of gonads of Drosophila melanogaster with different genotypes, including a metafemale 3X;2A and an intersex XXY;3A have revealed that the formation of synaptonemal complexes is controlled by the genic balance, i.e., the ratio of X chromosomes to autosomes. The Y chromosome is not involved in the genetic control of the formation of precursors of the central element of synaptonemal complexes in males, nor does it disturb their formation in XXY females. Hyperploidy for sections 1-3A and 18A-20 of the X chromosome does not lead to the appearance of synaptonemal complexes in males and does not interfere with their formation in females. Females hyperploid for extensive regions of the X chromosome (sections 1-11A, 11A-20, and 8C-20) are fertile and show apparently normal formation of synaptonemal complexes. Hyperploidy for sections 8C-11A of the X results in a sharp decrease in the viability of females, in abnormal differentiation of ovary cells, and in the lack of synaptonemal complexes. These data suggest a possible important role for the sections 8C-11A in the genic balance controlling the formation of synaptonemal complexes in D. melanogaster. The lack of synaptonemal complexes in hypoploid females may be the result of abnormal cell differentiation in gonads.     

Increased incidence of hyperhaploid 24,XY spermatozoa detected by three-colour FISH in a 46,XY/47,XXY male

Meiotic segregation of gonosomes from a 46,XY/47,XXY male was analysed by a three-colour fluorescence in situ hybridisation (FISH) procedure. This method allows the identification of hyperhaploid spermatozoa (with 24 chromosomes), diploid spermatozoa (with 46 chromosomes) and their meiotic origin (meiosis I or 11). Alpha satellite DNA probes specific for chromosomes X, Y and 1 were observed on 27,097 sperm nuclei. The proportions of X-and Y -bearing sperm were estimated to 52.78% and 43.88%, respectively. Disomy (24,XX, 24,YY, 24,X or Y,+1) and diploidy (46,XX, 46,YY, 46,XY) frequencies were close to those obtained from control sperm, whereas the frequency of hyperhaploid 24,XY spermatozoa (2.09%) was significantly increased compared with controls (0.36%). These results support the hypothesis that a few 47,XXY germ cells would be able to complete meiosis and to produce mature spermatozoa.     

多重荧光定量PCR技术快速诊断21三体及18三体方法的建立及临床应用

利用收集的20例21三体、3例18三体DNA样本及40例正常人DNA样本,选择多对21、18号染色体短串联重复序列分子标记,建立多重荧光定量PCR检测技术用于21三体、18三体的快速产前诊断;利用建立的方法对165例产前诊断病例及4例消化道畸形新生儿进行检测,并与核型分析结果相比较。169例病例中共诊断21三体4例,18三体1例,所有病例均在1～3d得到结果,无漏诊和误诊,并利用建立的多重荧光定量PCR技术为5例核型分析失败的病例提供了明确的产前诊断。对于同期B超检查胎儿结构异常的22例胎儿,则采用传统的核型分析,检出1例(45,X),1例(47,XXY)。结果表明建立的多重荧光定量PCR技术可快速、准确地诊断21三体和18三体,减轻核型分析需时过长给孕妇带来的焦虑,可用于血清学筛查21三体、18三体高风险者及高龄孕妇,也适用于对其他遗传性疾病如遗传性耳聋进行产前诊断时并行检测以排除21三体和18三体。多重荧光定量PCR技术结合传统核型分析可更好的满足产前诊断的临床需求。     

Occlusion in 47,XXY (Klinefelter syndrome) men.

Occlusal morphology of permanent dentitions in 29 men with a 47,XXY chromosome complement (Klinefelter syndrome) was determined from dental casts. The results showed that a relatively frequent occlusal anomaly was mesial molar occlusion. Incisal open bite was also more common than in controls. Based on the present and previous observations of occlusal anomalies in various sex chromosome anomaly groups and normal controls, it is suggested that the presence of the Y chromosome in the genome is at least as important as the X chromosome for the development of harmonious occlusal morphology. The tendency towards sexual dimorphism in occlusal phenotype might result from a differential effect of the X and Y chromosomes on cellular activity which leads to different growth patterns.     

Differential sex chromosome replication and dosage compensation in polytene trichogen cells of Lucilia cuprina (Diptera: Calliphoridae)

Non banded sex chromosome elements have been identified in polytene trichogen cells of Lucilia cuprina using Y-autosome translocations, C-banding and Quinacrine fluorescence. The X chromosome is an irregular granular structure while the much smaller Y chromosome has both a dense darkly stained and a loosely organised segment. The X and Y chromosomes are underreplicated in polytene cells but comparison of C- and Q-banding characteristics of sex chromosomes in diploid and polytene tissues indicates that selective replication of non C-banding material occurs in both the sex chromosomes. Brightly fluorescing material in the Y chromosome is replicated to such an extent that it consists of half the polytene element, while the C-banding material, which makes up most of the diploid X chromosome, is virtually unreplicated. Differential replication also occurs in autosomes. In XXY males, and in males carrying a duplication of the X euchromatic region, a short uniquely banded polytene chromosome is formed. It is suggested that in males carrying two doses of X euchromatin a dosage compensation mechanism operates in which genes in one copy are silenced by forming a banded polytene chromosome.     

Q-banding of chromosomes in human spontaneous abortions

Chromosome studies of 242 spontaneous abortions were carried out by Q-banding technique. The abortuses were selected for study because they were phenotypically abnormal, had not progressed beyond 12 weeks development or were from women with repeated abortions. Chromosome anomalies were found in 126 (52%) of the abortuses. Of these, 71 (56%) were trisomies. Trisomies were found for all the autosomes except Nos. 1, 3, 5, 11, 17 and 18. Triploidy was the second commonest anomaly in this series, making up 26 (21%) of the total anomalies. About 70% of these had an XXY sex chromosome complement. Only 16 (13%) of the abortuses had X monosomy, a lower frequency than would be expected in an unselected study. Tetraploidy was found in 8 abortuses and the 5 remaining specimens had various anomalies. These included 3 translocations, a trisomy 21,X monosomy and a ring chromosome 13. Except for the greater frequency of XXY than XXX sex chromosomes in the triploids, there was no evidence of a distortion of the sex ratio, either among the trisomic or among the chromosomally normal abortuses.