Search

Donor-derived hematopoiesis was assessed in 17 patients who received allogeneic marrow grafts from HLA-matched siblings between 1971 and 1980. Complete blood counts were normal or near normal in all patients except one. Chimerism analyses, using either dual-color XY-chromosome fluorescence in situ hybridization (FISH) or analysis of variable number tandem repeat loci, indicated that 15 out of 16 patients had greater than 97% donor-derived hematopoiesis, whereas 1 patient had indeterminate chimerism. All 12 recipients of grafts from female donors exhibited polyclonal hematopoiesis by X-linked clonal analysis with the use of molecular probes. Of the 17 recipients, 9 exhibited a less than 1.0-kilobase shortening of granulocyte telomere length compared with their respective donors, according to terminal restriction fragment analysis or flow-FISH with a fluorescein-labeled peptide nucleic acid probe. These data suggest that under standard transplantation conditions, the stem cell proliferative potential is not compromised during hematopoietic reconstitution. (Blood. 2000;96:3991-3994)

Objective: Although most methods for selecting the sex of offspring by sorting spermatozoa are ineffective at shifting the ratio of Y- to X-containing cells, some commercial sources continue to offer such services. Our objective was to evaluate commercially "sorted" samples with use of dual-color fluorescence in situ hybridization and to identify variations in assessment by comparing motile and total sperm populations, donors, observers, and fluorescence in situ hybridization probes., Study Design: Cryopreserved sperm from seven anonymous donors were processed as for insemination. Sperm cells from each total sample or motile subfraction were prepared for fluorescence in situ hybridization by incubation with disulfide-reducing agents to expand sperm nuclei. Two sets of X and Y chromosome-specific, fluorophore-labeled deoxyribonucleic acid probes were used. At least 400 nuclei from each preparation were classified independently by three blinded observers. Hybridization efficiency, aneuploidy, and sex chromosome content were evaluated in subsets of five unsorted, five female-oriented, and five male-oriented samples. Total and motile subfractions were compared with eight samples. Fluorescence in situ hybridization probes were compared in five paired unsorted samples., Results: No differences were detected between washed samples and paired motile subfractions. No differences in hybridization and aneuploidy were detected between groups of sorted samples. The Y/X ratio was significantly different between the sorted groups. However, male-oriented samples had a lower Y/X ratio than female-oriented samples did. Observer and probe choice accounted for small but significant variations that did not alter conclusions about the X/Y ratio for sorted samples., Conclusion: In a series of 10 sorted samples from one commercial source, dual-color fluorescence in situ hybridization demonstrated a small but significant shift in the sex chromosome ratios among samples. However, this shift was opposite to that expected by the orientation of the sorted samples.

Unlike the centromeres of other species, the "compound' centromeres of the Indian muntjac span over exceptionally extended regions (Brinkley et al., 1984). We extend this concept and show that some of these centromeres are divisible into several chromomeres in which the light staining regions alternate with the dark staining C-band positive segments. Unlike the centromeres of other species where the centromere replicates as one unit, the replication of the sub-units constituting the centromere of the X-chromosome in the muntjac occurs at different times as at least three independent segments. The CREST staining of the centromere regions of even the smallest (Y2) chromosome is interrupted by non-staining segments. Electron microscopy shows similar interruptions in the continuity of the trilamellar kinetochore. Sister chromatid exchanges occur in the region of the centromeres and chromatid breaks within the centromere region occur in the non-fluorescent segments. We interpret these data to suggest that the centromere regions of the Indian muntjac are made up of independent multiple centromeres interrupted by non-centromeric chromatin. Relevance of these parameters in mutagenesis is briefly discussed.

Almost half of all cases of severe hemophilia A are caused by recurrent DNA inversions, which disrupt the factor VIII (FVIII) gene. These inversions generally occur between a region of intron 22 (int22h) and one of two homologous copies of this region, located 300 to 400 kb telomeric to the FVIII gene. They are routinely detected by a Bcl I Southern blot assay in which the sizes of two of the three normal hybridization bands are characteristically altered. However, atypical hybridization patterns have been observed, and this report describes the first detailed analysis of a hemophilia A patient with such a pattern. The abnormal result was found to be caused by a novel FVIII inversion involving an extra copy of int22h from a site only 70 to 200 kb telomeric of the FVIII gene. Polymerase chain reaction (PCR) allowed one of the inversion junctions to be analyzed, showing that the int22h sequence at this inversion junction was truncated. This patient and his novel inversion provide further evidence that int22h is associated with instability in Xq28.

T-cell prolymphocytic leukemia (T-PLL), a rare form of mature T-cell leukemias, and ataxia telangiectasia clonal proliferation, a related condition occurring in patients suffering from ataxia telangiectasia, have been associated to translocations involving the 14q32.1 or Xq28 regions, where are located the TCL1 and MTCP1 putative oncogenes, respectively. The MTCP1 gene is involved in the t(X;14)(q28;q11) translocation associated with these T-cell proliferations. Alternative splicing generates type A and B transcripts that potentially encode two entirely distinct proteins; type A transcripts code for a small mitochondrial protein, p8MTCP1, and type B transcripts, containing an additional open reading frame, may code for 107 amino-acid protein, p13MTCP1. The recently cloned TCL1 gene, also involved in translocations and inversions associated with T-cell proliferations, codes for a 14-kD protein that displays significant homology with p13MTCP1. We have generated rabbit antisera against this putative p13MTCP1 protein and screened for expression of p13MTCP1 normal lymphoid tissues and 33 cases of immature and mature lymphoid T-cell proliferations using a sensitive Western blot assay. We also investigated the MTCP1 locus configuration by Southern blot analysis. The p13MTCP1 protein was detected in the three T-cell proliferations with MTCP1 rearrangements because of t(X;14) translocations, but neither in normal resting and activated lymphocytes nor in the other T-cell leukemias. Our data support the hypothesis that p13MTCP1 and p14TCL1 form a new protein family that plays a key role in the pathogenesis of T-PLL and related conditions.

Males with a 46,XX karyotype generally have Y chromosomal material translocated to the pseudoautosomal region of the X chromosome. We have delineated two such cases using two color fluorescent in situ hybridization with probes from the short arm (DYZ2), centromere (DYZ3), and long arm (DYZ1) of the Y chromosome and a centromeric probes for the X chromosome (DXZ1). Using these techniques, the two patients are identified as having the karyotype 46,X,der(X)t(X;Y) (p22;p11) and a phenotype consistant with this translocation. Azoospermia in these patients is explained by the absence of Y long arm material including the recently identified candidate gene family for spermatogenesis.

The cause of the Rett syndrome remains unknown but is thought to be related to X-chromosome abnormalities. Restriction fragment length polymorphism analysis was employed to search for X-chromosome DNA rearrangements and uniparental disomy in 16 probands and their families. Eighteen different probes, each specific for an area on either the long or the short arm of the X-chromosome, were used. DNA rearrangements were not detected at any of the tested loci. In addition, at each informative locus evidence of both maternal and paternal contributions was found in all probands. Thus, no evidence of either chromosomal abnormality or uniparental disomy was found in the population studied. If uniparental disomy is indeed a causative genetic mechanism for the Rett syndrome, its occurrence may only be infrequent.

In the past few years, clinical, cytogenetic and molecular analysis of patients with complex phenotypes has led to the identification of syndromes caused by deletions of adjacent disease genes on a chromosome. These conditions, referred to as contiguous deletion syndromes, are an important component of the syndromes recognized in medical genetics, and the DNA from patients affected by these disorders is useful for the mapping and cloning of disease genes.

A 25-year-old phenotypic female with primary amenorrhoea was referred for chromosomal analysis. Earlier she had undergone hormonal therapy but showed no response. The secondary sex characters were of female type, with poor breast development. Laparoscopic findings revealed the presence of a very small uterus; the right ovary was found to be undeveloped and the left was absent. Cytogenetic study revealed a case of triple-X with deletion of the terminal region of the long arm of one of the X chromosomes [Xq27.3]. Among the 100 buccal mucosa cells analysed, 30 cells showed double Barr bodies. Hormonal studies using RIA technique revealed normal levels of prolactin (9.1 ng/ml), a high level of FSH and LH (135 and 61 mIU/ml) and low levels of estradiol and progesterone (12 pg/ml and 0.20 ng/ml respectively). To our knowledge, this may be the first report of a triple X with deletion of the X chromosome associated with primary amenorrhoea.

A de novo paracentric inversion of the short arm of an X chromosome (p11.2p22.1) was observed in a 17-year-old girl studied because of primary amenorrhea and a Turner phenotype. To our knowledge this is only the second case of a paracentric inversion of the X chromosome short arm reported, the first having been briefly described in 1982, in a young lady with the Turner phenotype. In spite of its balanced appearance, there is little doubt that this rearrangement is the cause of the phenotypic anomalies of the patient, probably as the result of gene(s) modification(s) at the breakpoints on the X chromosome, or because the inverted gene sequence resulted in modifications by position effect. It has become increasingly difficult to recognize obvious phenotype-genotype correlations in Turner syndrome, given the multiplicity of chromosome rearrangements--some of them quite subtle--which are associated with ovarian dysgenesis.

Twenty independent man-mouse (Cl1D,LA/TK-, HPRT-) and man-hamster (CH,HPRT-) hybrids using female human cells with balanced reciprocal translocation XX,t(X;5)(q21;q11) were analyzed for human genes localized on chromosome 5 (HEXB), on chromosome X (PGK, GALA, HPRT, G6PD) and for the different chromosomes in relation with the balanced reciprocal translocation (chr.5, chr.5q-, chr.Xq+, chr.X). The different results obtained indicate that the genes for human markers HEXB, PGK are on Xq+, and that the genes for human markers GALA, G6PD are on 5q-. These data implicate finally the following localizations: HEXB on 5q11 leads to 5qter; PGK on Xq21 leads to Xpter; GALA, HPRT, G6PD on Xq21 leads to Xqter.

In the 'doubling-dose' method currently used in genetic risk evaluation, two principle assumptions are made and these are: (1) there is proportionality between spontaneous and induced mutations and (2) the lesions that lead to spontaneous and induced mutations are essentially similar. The studies reported in this paper were directed at examining the validity of these two assumptions in Drosophila. An analysis was made of the distribution of sex-linked recessive lethals induced by MR, one of the well-studied mutator systems in Drosophila. Appropriate genetic complementation tests with 15 defined X-chromosome duplications showed that MR-induced lethals occurred at many sites along the X-chromosome (in contrast to the known locus specificity of MR-induced visible-mutations); some, but not all these sites at which recessive lethals arose in the MR-system are the same as those known to be hot-spots for X-ray-induced lethals. With in situ hybridization we were able to demonstrate that a majority of MR-induced lethals is associated with a particular mobile DNA sequence, the P-element, i.e. they arose as a result of transposition. The differences between the profiles of MR-induced and X-ray-induced recessive lethals, and the nature of MR-induced and X-ray-induced mutations, thus raise questions about the validity of the assumptions involved in the use of the 'doubling-dose' method.

Hereditary X-linked thrombocytopenia occurs either as isolated thrombocytopenia or as a part of the Wiskott-Aldrich syndrome (WAS). We studied X-linked thrombocytopenia in a family with eight affected male members, none of whom exhibited the increased susceptibility to infection that occurs in WAS. We found a significant linkage between thrombocytopenia and DXS 146, a marker on the proximal part of the short arm of the X-chromosome. WAS has previously been mapped to the same chromosomal region. The present findings indicate that X-linked thrombocytopenia and WAS are closely related and may even be caused by different mutations of the same gene. This view is supported by our findings of atopic symptoms and minor deviations in immunologic variables among some of the affected subjects.

A 16 year-old girl with short stature and gonadal dysgenesis was found to have a chromosomal complement consisting of 46,X,dic(X) (qter yields p22::p22 yields qter). When comparing her clinical features with 7 other cases who appeared to have precisely the same abnormal dicentric X, it was found that even though the percent of 45,X cells present varied considerably from patient to patient, these patients were remarkably similar and the stigmata, of Turner's syndrome were minimal in this group as a whole.

X-specific DNA probes were used to characterize the r(X) of a 45,X/46,X,r(X) female patient with Incontinentia pigmenti. It was found to be of maternal origin. Breakpoints were shown to be in or distal to p11.22 and between q12.2 and q13.1. When considering all known cases of Incontinentia pigmenti and X rearrangements at least four different break sites on the X have been shown.

The karyotypes of 4 species of bats, Artibeus lituratus (Phyllostomatidae), Pipistrellus pipistrellus (Vespertilionidae), Pteropus alecto and P. giganteus (Pteropodidae), were studied after several banding techniques. For A. lituratus, in which an X-autosome translocation was observed, an analyse of the replication pattern in the rearranged chromosome was also made after BrdU incorporation.

Spontaneous interchange between the X chromosomes and the C(2L) autosomal compound in their centromeric regions was studied in y/XY;C(2L);C(2R) and In(1)dl-49+BM1/XY;C(2L);C(2R) Drosophila melanogaster females. These females were mated with F(2L)/F(2L);C(2R) males. Interchange occurrence was recorded as the appearance of an F1 individual with a half-translocation of either X . 2L or Y . 2L type. 37 interchanges were recovered in y/XY and 67 in In(1)/XY females. The majority of the interchanges were of meiotic origin. The interchanges were mainly C(2L)-XY; the most frequent type of half-translocation was Y . 2L;dl-49+BM1. Inversion increased about 5-fold the interchange frequency. In the course of C(2L)-XY interchange, the other X chromosome and C(2R) compound regularly paired and disjoined. In y/XY females, 8 crossover half-translocations of meiotic origin were recovered. The results obtained indicate that meiotic pairing between the X's and C(2L) occurred in the females examined. According to our estimates, XY-C(2L) pairing is associated with interchange in the heterochromatic centromeric regions with a frequency of 10(-3). The recovery of crossover half-translocations supports the chromocentral model of non-homologous pairing and allows us to assume that a chromosome may simultaneously pair with a homologue and a non-homologue. The disjunction pattern of this trivalent depends on its structure in each particular case. The chromosome-segregation pattern resulting from spontaneous interchanges was similar to that resulting from radiation-induced interchanges in the immature oocytes described by Parker. This similarity suggests that non-homologue pairing occurs in the immature oocytes too. The non-homologue-pairing pattern established by the interchange test conformed well with that previously established in y/XY and In(1)XY females by the distribution test.

A long X-chromosomal inversion in the mouse was used to suppress crossing-over and thereby to scan 85% of the X-chromosome, or 5% of the genome, for recessive lethal mutations induced by radiation. After a fractionated absorbed dose of 500 + 500 rad X-rays 24 h apart to spermatogonia, 2/536 irradiated and 0/529 control X-chromosomes carried a confirmed lethal. This corresponds to a rate for recessive lethals of 1.9 x 10(-6)/rad/X-chromosome for single exposures (allowing for the enhancing effect of fractionation). This is believed to be the first demonstration of the induction of transmissible X-linked lethals in mammals. The results are consistent with previous findings by other methods and indicate the relatively low rate of induction of lethals and the value of inversions in detecting them.

In the rad-4 mutant of C. elegans there is a specific increase in the number of 'Disjunction Regulator Regions' (DDR) present on the synaptonemal complexes (SC) in pachytene nuclei. These DRRs either promote disjunction or inhibit nondisjunction of the X-chromosome as evidenced by the 10-fold decrease in the rate of X-chromosome nondisjunction as compared to the wild-type. The structure of the tripartite SC is normal, thus, the decrease in the rate of X-chromosome nondisjunction in the rad-4 mutant is not related to the structure of the SC but may be related to the number of DRRs. Other changes are also associated with the sensitivity to irradiation, i.e. the pachytene nuclear morphology is altered such that nuclei and nucleoli are 50% the size of wild-type. In addition, the autosomal: X-chromosome size ratio is reduced in the rad-4 mutant. That there are six SCs confirms n = 6 in this mutant and of these six SCs three can be identified: (1) the XX bivalent, SC No. 1, is the shortest and pairs synchronously with the autosomes; (2) the longest bivalent, SC No. 6, carries the nucleolar organizer region at one extreme end; and (3) SC No. 5 has two DRRs located approximately one micron apart from each other.

The authors present the clinical and cytogenetic studies of a white malformed baby with dup (3p) secondary to the malsegregation of a maternal balanced (X;3) (p22.3;p21) translocation. Besides the typical clinical features he also presented polydactyly of both hands. X-replication findings of the mother's lymphocytes did not strictly follow the usual inactivation pattern of balanced X;A translocations.

In a patient suffering from X-linked chronic granulomatous disease (X-CGD)--a disorder of phagocytesuperoxide generation--and McLeod syndrome, characterized by the absence of the red cell Kell antigen, we identified a deletion of the entire X-CGD gene by means of DNA hybridization with a cDNA probe. Our findings suggest that the X-CGD and McLeod loci are physically close in the p21 region of the X chromosome proximal to the Duchenne muscular dystrophy locus.

Three patients with male habitus, short stature and testicular differentiation are described. All had mos 45,X/46,XY, the ratio of the two stemlines varying between the patients and between different tissues. The Y chromosome was abnormal, lacking the brilliant QFQ fluorescence and dark CGB staining characteristic of the distal part of the normal Y. Detailed banding studies suggested that the short arm and proximal part of the long arm were normal, while the distal part of the long arm was molecularly or otherwise altered, resulting in abnormal staining properties. Two of the patients were tested for H-Y antigen and found to be positive. These data and those collected from the literature are compatible with a model in which the primary lesion in X/XY mosaicism is a molecular alteration in the reiterated Y-specific DNA sequences (and possibly neighbouring sequences) of a 46,XY zygote resulting in the frequent mitotic loss of the Y and the emergence of a 45,X line. Provided the testis-determining gene(s) near the centromere are normal, testes are formed and the patient is H-Y antigen-positive. The extent of male or female differentiation depends in part on the prevalence, time of occurence, and distribution of the 45,X line and possibly in part on the alteration of other genes involved in sex differentiation and located on Yq further from the centromere.

Cultured secondary Syrian hamster embryo cells exposed to 0.5 N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) microgram/ml medium exhibited chromatid type of aberrations consisting of gaps, breaks and exchanges. Although no specific chromosome or chromosome segment was preferentially affected, chromosomes belonging to the larger groups tended to more often involved. G-band analysis demonstrated that 80% of the lesions occurred in negative bands, 9% involved the centromere, 3% were on non-banded heterochromatin, and approximately 8% of the lesions could not be definitely categorized by G-band analysis. Whether the lesions occur at positive bands or at the interface between negative and positive bands is difficult to discern by the G-band resolution. The Y chromosome compared to autosomes of similar size rarely had lesions. X chromosome damage was found in both the euchromatic and heterochromatic arms. However, both sex chromosomes, as well as an autosome (E20) which is heterochromatic on its long arm, were not found joined to the chromatids of other chromosomes, further emphasizing that chromosomes with large heterochromatic areas are isolated in terms of chromatid exchange events. The analysis of MNNG induced chromosome damage indicates that the negative bands are the primary site of damage and points of exchange.

Cytogenetic characterizations were made of lymphocyte colonies established from somatic mutation assays for 6-thioguanine (TG) resistance in Hiroshima atomic bomb survivors. G-banded chromosomes were analyzed in both TG-resistant (TGr) and wild-type colonies. Included were 45 TGr and 19 wild-type colonies derived from proximally exposed A-bomb survivors, as well as colonies from distally exposed control individuals who did not receive a significant amount of A-bomb radiation (18 TGr and 9-wild type colonies). Various structural and numerical chromosome abnormalities were observed in both TGr and wild-type colonies. Aberrations of the X chromosome, on which the hypoxanthine guanine phosphoribosyl transferase (HPRT) locus is present, were found in 6 colonies: 2 resistant colonies from controls (45,X/46,XX; 46,X,ins(X)), 3 resistant colonies (45,X/46,XX/46,X, + mar; 46,X,t(Xq +;14q-); 46,Y,t(Xq-;5q +)), and 1 wild-type colony (45,X/47,XXX) from proximally exposed persons. In cases with exchange aberrations, each of the break points on the X chromosome was situated proximally to band q26 where the HPRT locus is known to be assigned. DNA-replicating patterns were also studied, and it was found that abnormal X chromosomes showed early replicating patterns, while normal X chromosomes showed late replicating patterns.