G6PD-Puerto Limón: A new deficient variant of glucose-6-phosphate dehydrogenase associated with congenital nonspherocytic hemolytic anemia

Summary H-Y antigen was examined in eight male patients with X polysomies, namely four patients with 47,XXY, one patient with 48,XXXY, two patients with 49,XXXXY, and one patient with the mosaic 47,XXY/49,XXXXY. In all patients the H-Y antigen titers were lower than in normal 46,XY males. However, a linear correlation between the number of additional X chromosomes and the reduction of H-Y antigen titers could not be demonstrated. Such a correlation would be expected if the gene for the repressor of H-Y antigen expression is active also on the additional X chromosomes.     

X-linked genes of the H-Y antigen system in the wood lemming (Myopus schisticolor)

Summary H-Y antigen was investigated in 18 specimens representing six different sex chromosome constitutions of the wood lemming (Myopus schisticolor). The control range of H-Y antigen was defined by the sex difference between normal XX females (H-Y negativeper definitionem) and normal XY males (H-Y positive, full titer). H-Y antigen titers of the X^*Y and X^*0 females were in the male control range, while in the X^*X and X0 females the titers were intermediary. Data were obtained with two different H-Y antigen assays: the Raji cell cytotoxicity test and the peroxidase-antiperoxidase (PAP) method. Fibroblasts, gonadal cells, and spleen cells were checked. Presence of full titers of H-Y antigen in the absence of testis differentiation is readily explained by the assumption of a deficiency of the gonadspecific receptor of H-Y antigen. Since sex reversal is inherited as an X-linked trait, genes for this receptor are most likely X-linked. The implications of our findings are discussed in connection with earlier findings concerning H-Y antigen in XY gonadal dysgenesis in man and the X0 situation in man and mouse.     

Genetic aspects of H-Y antigen

Summary While it remains to be clarified what detection of H-Y antigen by current methods means, the existence of a factor governing testicular differentiation of the indifferent gonadal anlage seems to be well established. There are various kinds of evidence that H-Y antigen as a biologically meaningful factor has a complex genetical basis. There is the contribution of the Y chromosome which, independent of the number of other chromosomes, especially of X chromosomes, leads to a male phenotype. The X chromosome must be involved also because structural aberrations of its distal short arm influence the expression of the H-Y structural gene. Due to examples of autosomal inheritance of various forms of sex reversal, an autosomal gene is assumed to be involved as well. Arguments are presented favoring the assumption that the structural H-Y gene is autosomal, while genes on the X and Y chromosomes have a controlling function.This genetic control mechanism for H-Y antigen seems to have evolved secondary to placentation in mammals. In non-mammalian vertebrates, H-Y antigen is controlled by other factors, e.g. steroid hormones. While the functional role of H-Y antigen in directing differentiation of the heterogametic gonad appears to have been preserved during evolution, the mechanism of its control has changed. This latter mechanism is only poorly understood.     

Mitotic cycles in human cell strains with sex chromosomes aneuploidy

Summary A persistence of the embryonic type of mitotic cycle was found in postnatal strains with aneuploidy of sex chromosomes (45,X; 47,XXX; 49,XXXXX;47,XYY;49,XXXXY). Life-span and proliferating activity of the strains did not differ from those of diploid postnatal cells.     

A gene controlling H-Y antigen on the X chromosome

Summary The existence of a strict correlation between presence of testicular tissue and presence of H-Y antigen in mammals and man leads to the conclusion that H-Y antigen is an essential differentiation factor in testicular morphogenesis. Presence of low titers of this differentiation antigen even in fertile females indicates that its morphogenetic effect depends on a threshold. Here, studies on H-Y antigen in female individuals with various deletions of the X-chromosome are reported. It turns out that deletion of Xp results in the synthesis of reduced amounts of H-Y antigen, while deletion of Xq does not. In a fertile female with only Xp223 deleted due to an X/Y translocation, including the distal Yq, presence of a reduced H-Y titer allows for the tentative assignment of a controlling gene repressing the H-Y structural gene. From the cases studied, it follows that the H-Y structural gene is autosomal and under the control of X- and Y-linked genes. The conception emerges that interaction between X- and Y-linked genes or their products results in variation of the H-Y antigen titer. The fate of the indifferent gonadal anlage to differentiate into the male or the female direction will depend on the titer of H-Y antigen reached by the action or interaction of the controlling genes involved.Supported by the Deutsche Forschungsgemeinschaft (SFB 46)     

Parental origin of the extra chromosomes in polysomy X

Five polymorphic index markers were analyzed by polymerase chain reaction (PCR) to ascertain the parental origin of the extra X chromosomes in seven polysomic cases (one 49,XXXXX, three 49,XXXXY, two 48,XXXY, and one 48, XXYY). All four X chromosomes in 49, X polysomies were maternal in origin and the extra X chromosomes in 48 X polysomies were paternal. In each case the multiple X chromosomes were contributed by a single parent. Taken together with previously reported cases, these data support a single mechanism of sequential nondisjunction during either maternal or paternal gametogenesis as the cause of higher order sex chromosome polysomy.     

Effects of sex chromosome dosage on corpus callosum morphology in supernumerary sex chromosome aneuploidies

Background

Supernumerary sex chromosome aneuploidies (sSCA) are characterized by the presence of one or more additional sex chromosomes in an individual’s karyotype; they affect around 1 in 400 individuals. Although there is high variability, each sSCA subtype has a characteristic set of cognitive and physical phenotypes. Here, we investigated the differences in the morphometry of the human corpus callosum (CC) between sex-matched controls 46,XY (N =99), 46,XX (N =93), and six unique sSCA karyotypes: 47,XYY (N =29), 47,XXY (N =58), 48,XXYY (N =20), 47,XXX (N =30), 48,XXXY (N =5), and 49,XXXXY (N =6).

Methods

We investigated CC morphometry using local and global area, local curvature of the CC boundary, and between-landmark distance analysis (BLDA). We hypothesized that CC morphometry would vary differentially along a proposed spectrum of Y:X chromosome ratio with supernumerary Y karyotypes having the largest CC areas and supernumerary X karyotypes having significantly smaller CC areas. To investigate this, we defined an sSCA spectrum based on a descending Y:X karyotype ratio: 47,XYY, 46,XY, 48,XXYY, 47,XXY, 48,XXXY, 49,XXXXY, 46,XX, 47,XXX. We similarly explored the effects of both X and Y chromosome numbers within sex. Results of shape-based metrics were analyzed using permutation tests consisting of 5,000 iterations.

Results

Several subregional areas, local curvature, and BLDs differed between groups.Moderate associations were found between area and curvature in relation to the spectrum and X and Y chromosome counts. BLD was strongly associated with X chromosome count in both male and female groups.

Conclusions

Our results suggest that X- and Y-linked genes have differential effects on CC morphometry. To our knowledge, this is the first study to compare CC morphometry across these extremely rare groups.

     

Abnormalities of human sex chromosomes

Summary The cytogenetic study of a pair of identical, mentally-retarded twins with the chromosome complement 48,XXXY is reported, along with extensive clinical and endocrinological studies of one twin.The genetic and clinical features of 30 reported 48,XXXY individuals were summarized and compared to those of 47,XXY and 49,XXXXY individuals. For 47,XXY the mean maternal age clearly is increased; for 48,XXXY it appears definitely but only slightly increased; and for 49,XXXXY it may not be increased at all. Developmental defects, similar in type, appear to be progressively more marked when an additional 1, 2, or 3 X chromosomes are added to the normal male chromosome complement. 47,XXY individuals may be either normal in intelligence or mentally retarded, whereas severe mental retardation has been present in all those with the complements 48,XXXY and 49,XXXXY.The interesting suggestion of increased twining associated with poly-X male complements is noted.

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Zusammenfassung Die cytogenetische Untersuchung eines Paares eineiiger, geistig zurückgebliebener Zwillinge mit dem Chromosomenstatus 48,XXXY wird dargestellt; bei dem einen Paarling konnten außerdem ausgedehnte klinische und endokrinologische Studien durchgeführt werden.Außerdem wurden die genetischen und klinischen Merkmale der 30 bekannten Fälle mit 48,XXXY dargestellt und mit denen von Patienten mit 47,XXY und mit 49,XXXXY verglichen. Bei Fällen mit 47,XXY ist das mütterliche Alter deutlich erhöht; bei 48,XXXY ist es eindeutig, aber nur leicht erhöht; es sieht so aus, als ob es für 49,XXXXY überhaupt nicht erhöht wäre. Defekte der Entwicklung, die dem Typ nach ähnlich sind, scheinen dem Ausmaß nach desto mehr ausgeprägt zu sein, je mehr X-Chromosomen zusätzlich bei dem normalen männlichen Chromosomensatz vorhanden sind. 47,XXY Individuen können entweder schwachsinnig sein oder eine normale Intelligenz haben; dagegen zeigten alle Fälle mit 48,XXXY und 49,XXXXY einen schweren Schwachsinn.Es wird die interessante Frage aufgeworfen, ob die Zwillingshäufigkeit bei Poly X-Männern erhöht ist.

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Research supported by grants HD 04134, HL 09011, RR-47, AM-11105, and TIAM 53950-11 from the National Institutes of Health.     

Polymorphic karyotypes and sex chromosomes in the tufted deer (Elaphodus cephalophus): cytogenetic studies and analyses of sex chromosome-linked genes

Different diploid chromosome numbers have been reported for the tufted deer Elaphodus cephalophus (female, 2n = 46/47; male, 2n = 47/48) in earlier reports. In the present study, chromosomal analysis of seven tufted deer (5 male symbol, 2 female symbol) revealed that the karyotype of these animals contains 48 chromosomes, including a pair of large heteromorphic chromosomes in the male. C-banding revealed these chromosomes to be very rich in constitutive heterochromatin. Chromosome banding and PCR of sex chromosome-linked genes (SRY, ZFX, ZFY) performed on DOP-PCR products of single microdissected X and Y chromosomes confirmed that the large telocentric chromosome without secondary constriction is the X chromosome whereas the subtelocentric chromosome is the Y. The increased size of both, the X and Y chromosome, appears to be at least partially attributable to the presence of substantial amounts of heterochromatin.     

Turner syndrome patients are H-Y positive

Summary H-Y antigen was examined in six patients exhibiting the characteristic features of Turner syndrome. Five of the patients were of the karyotype 45,X, and one was a mosaic 45,X/46,Xi(Xq). H-Y antigen was detected in all of them, however, compared to male controls, their antigen titer was reduced. Within the intermediate range between female and male controls, considerable interindividual variation was detected among the patients which could be due at least in part to biological variation. The findings permit the inference that the H-Y structural gene is not Y-linked, and support the assumptions of an X-linked gene escaping inactivation and of it controlling the expression of the H-Y structural gene. It is probable that the structural gene itself is autosomal. The results also suggest that male gonadal differentiation is dependent on a threshold level of H-Y antigen concentration.Supported by the Deutsche Forschungsgemeinschaft (SFB 46)     

XXXXY syndrome in a phenotypic male infant with associated cardiac abnormalities

Summary A boy with 49,XXXXY karyotype is described with only mild mental retardation at 18 months. Physical abnormalities included patent ductus arteriosus, undescended testes, small penis, bilateral epicanthal folds, and incurved 5th digits with small middle phalanges. Literature review showed 7 previous cases of XXXXY patients with congenital heart disease. 23% of buccal cells showed 1 sex chromatin body; 26% showed 2 and 11% 3. Autoradiography demonstrated 3 heavily labelled X chromosomes. The heteropyknotic behavior of X Chromosomes in excess of one may provide some measure of protection against excessive numbers of X chromosomes, bence the relatively normal development of some XXXXY patients.This study was supported in part by research grant AM-02504 from the National Institute of Arthritis and Metabolic Diseases U.S. Public Health Service.     

What causes the abnormal phenotype in a 49,XXXXY male?

Summary The chromosome replication pattern of a man with 49,XXXXY was analyzed using ³H-thymidine and autoradiography as well as BrdU and acridine orange. The former technique showed a highly irregular replication pattern; the latter revealed one early replicating X chromosome, and the other three more or less asynchronously replicating. Two hypotheses seem to explain best the abnormal phenotype of males with an XXXXY sex chromosome constitution: (1) The number of the always active regions (tip of Xp) and of the possibly always active regions (the Q-dark regions on both sides of the centromere) is increased from one to four. (2) The replication pattern of the late-replicating X chromosomes is highly asynchronous, which might affect the phenotype. The possibility that more than one X chromosome might remain active in some cells, an even more abnormal and obviously deleterious situation, is still open.     

H-Y antigen as a tool for the determination of the heterogametic sex in Amphibia

H-Y antigen was investigated in three amphibian species with different degrees of sex-chromosome differentiation: Bufo bufo, Triturus vulgaris, and Pyxicephalus adspersus. No heteromorphic sex chromosomes were found in B. bufo, but an examination of the progeny of hermaphrodites (Ponse, 1942) indicated that the female of this species was heterogametic (ZW). Sex chromosomes differing only by a very small heterochromatic region at their telomeres were found in the male of T. vulgaris (XY). Pyxicephalus adspersus revealed high differentiated ZW sex chromosomes. The results of the H-Y antigen studies on these three species indicate that H-Y antigen is expressed only in the heterogametic sex, irrespective of differences in morphological differentiation of the sex chromosomes. Therefore, H-Y antigen could be a valuable tool in determining the heterogametic sex, not only in Amphibia but possibly also in other vertebrate species that have either evolved no heteromorphic sex chromosomes or where sex-reversal experiments are not possible.     

H-Y antigen expression in a case of XX true hermaphroditism

Summary Cells from an XX true hermaphrodite expressed a reduced amount of H-Y antigen when compared with normal XY cells and with cells from his father, who had an XY/XX chromosomal constitution. His mother had a normal karyotype and was H-Y negative. The four brothers of the patient were clinically and karyotypically normal. An X-Y interchange followed by random inactivation of the X chromosome is proposed to explain the H-Y antigen titer found in the patient.     

XY gonadal dysgenesis and the H-Y antigen

Summary H-Y antigen was determined in 12 patients affected by XY gonadal dysgenesis. Of these, three proved to be H-Y negative, and nine, including two sisters, were H-Y positive; two of the unrelated positive cases exhibited a reduced antigen titer. Therefore, this clinical condition must be genetically heterogeneous. It is assumed that in the negative cases and possibly in those with reduced antigen titer, the H-Y generating system is affected by mutation, while in the regular positive cases the target cells are unable to respond due to a defect of the gonad-specific H-Y antigen receptor.I dedicate this article to the memory of Ilse Aschmoneit     

Changes in chromosome positioning may contribute to the development of diseases related to X-chromosome aneuploidy

The radial positions of the centromeric regions of chromosomes 1 and X were determined in normal male fibroblasts (XY) and in fibroblasts from a patient with a rare case of XXXXY polysomy. The centromeric regions and presumably the whole territories of active X chromosomes were demonstrated to occupy similar, although not identical, positions in XY and XXXXY cells. The centromeres of inactive X chromosomes (Barr bodies) were located closer to the nuclear periphery as compared with the centromeres of active X chromosomes. In addition, it was established that the nuclear radial position of gene-rich chromosome 1 was changed in XXXXY cells as compared to normal XY cells. The data are discussed in the context of the hypothesis postulating that changes in nuclear positioning of chromosomal territories induced by the presence of extra copies of individual chromosomes may contribute to the development of diseases related to different polysomies.     

Testis-determining H-Y antigen in XO males of the mole-vole (Ellobius lutescens)

The XO sex chromosome constitution has been found in both sexes of the mole-vole (Ellobius lutescens) belonging to the rodent family Microtinae. This enigmatic species has apparently been enduring a 50% zygotic lethality. The current serological study revealed the presence in XO males and the absence from XO females of H-Y (histocompatibility Y) antigen. In all the mammalian species studied thus far, the expression of H-Y antigen strictly coincided with the presence of testicular tissue and not necessarily with the presence of the Y chromosome. The testis-organizing function of the H-Y gene appears to have been confirmed.In the mole-vole, X linkage of the testis-organizing H-Y gene is favored over its autosomal inheritance. Only X linkage of the H-Y gene creates a compelling evolutionary need to change the female sex chromosome constitution from XX to XO, and to abandon the dosage compensation by an X inactivation mechanism, so that the nonproductive X^H-YX zygote can be eliminated as an embryonic lethal. With regard to the electrophoretic mobilities of three X-linked marker enzymes, however, a genetic difference between the male-specific X^H-Y and the female-specific X was not detected. This might reflect a relatively recent speciation.     

Dicentric Y chromosome in a patient with gonadal dysgenesis and seminoma

Summary A male patient with ambiguous external genitalia developed a seminoma in the left inguinal region; his internal genitalia included a streak gonad on the right and a small uterus.Cytogenetic studies demonstrated a dicentric Y chromosome with unstable behavior during cell division, which resulted in 45,X/46,X,dic(Y)/47,X,dic(Y),dic(Y) mosaicism.Immunogenetic studies allowed the identification of the male-determining H-Y antigen on both leukocytes and red cells of the patient.The significance of these results is discussed with respect to recent data on the genetic control of H-Y antigen.This work was supported in part by CNR Centro di studio per l'Immunogenetica e l'Istocompatibilità     

Genetic control of H-Y synthesis. A hypothesis

Summary In view of the claimed serological H-Y positivity observed in patients with ovarian dysgenesis (for example, 45,X) and in XO mice (neither of whom have a Y chromosome), it is suggested that genetic control is exercised over the H-Y system by structural genes on the pairing segments of the X and Y chromosomes, acting on an autosomally coded H-Y precursor.     

A restriction-fragment-length difference detected by the anonymous probe DXS199 exhibits non-Mendelian inheritance.

Anonymous DNA probes were isolated from an X chromosome-enriched flow-sorted library. One of these probes, DXS199, identified a restriction-fragment difference that failed to show Mendelian segregation. All normal females were found to have two AvaII fragments of 6.5 kb and 6.0 kb, whereas all normal males had only the 6.5-kb fragment. DNA from a 49,XXXXY male was found to have both 6.0- and 6.5-kb AvaII fragments, in the same 3:1 ratio as seen in the inactive:active number of X chromosomes. This variant, which reflects a structural difference between active and inactive X chromosomes, is likely to be due to a methylation site on the active X chromosome.