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11/19. transplantation of stem cells of embryonic liver in a patient with severe combined immunodeficiency.

    A patient had severe combined immunodeficiency syndrome and X-chromosomal recessive heredity. Since the parents and siblings were not suitable as HLA-compatible bone marrow donors, stem cells from embryonic liver were transplanted intravenously in 3 stages (6 X 10(6); 3.5 X 10(6), and 9 X 10(7]. transplantation was tolerated well; there were no signs of a graft-versus-host reaction. Examination of the immunological condition after transplantation showed evidence of T-cell reconstitution, immunohistochemistry revealed beginning immune globulin production. The child died at the age of 5 months due to respiratory failure.
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12/19. Confirmation of prenatal diagnosis of sex chromosome mosaicism.

    prenatal diagnosis of mosaicism causes problems in interpretation and in genetic counselling. Part of the difficulty with any prenatal diagnosis of mosaicism is interpretation of results without knowing the exact origin, embryonic or extraembryonic, of the abnormal cell line. To confuse the issue in cases of prenatal diagnosis of 45,X/46,XY mosaicism is the recent demonstration that a diagnosis of 45,X/46,XY made prenatally is not necessarily associated with the same phenotype as when diagnosed postnatally. We present two cases of prenatal diagnosis of sex chromosome mosaicism (45,X/46,XY and 45,X/47,XYY). Posttermination examination of the phenotypically normal male fetuses and their placentas established that the placenta was the most likely source of the 45,X cell line. An approach to confirming the prenatal diagnosis of sex chromosome mosaicism and establishing its origin utilizing detailed cytogenetic examination of both fetus and placenta is suggested.
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13/19. Presumptive mosaic origin of an XX/XY female with ambiguous genitalia.

    A child with ambiguous genitalia had an XX/XY karyotype in all tissues examined. Analyses of 11 informative polymorphisms, both chromosomal and genetic (Rh and HLA), showed no difference between the two cell lines. It is unlikely that the child originated from fertilisation of the egg and the second polar body by two sperms; therefore, we hypothesise that the child originated from an XXY zygote after mitotic errors during cleavage. Recent findings of differences in the chromosome constitution between the extra-embryonic tissues and the fetus support this view.
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14/19. Testicular regression syndrome.

    Recently, the testicular regression syndrome has been reported as being representative of a clinical range of XY agonadal persons. A patient with aberrant fetal sexual development is described. Of particular interest is that all of the tissues examined--the rudimentary uterine horn and the 2 fallopian tubes--displayed an XY chromosome complement. Correlation was made between the known temporal events of embryogenesis of the testes and the apparent time of regression of the testes. In this patient, the insult to testicular development, with subsequent testicular regression, occurred between 48 and 60 days after fertilization. This review supports the previously reported thesis that in certain XY persons the testes are irreparably damaged at a critical stage in fetal development, and that this critical stage is represented by a range of abnormalities of genital development. Possible causes and simplified nomenclature for such gonadal damage are presented.
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15/19. Clinical, pathologic, and genetic findings in a case of 46,XY pure gonadal dysgenesis (Swyer's syndrome). II. Presence of h-y antigen.

    Evidence that expression of histocompatibility-Y (H-Y) antigen on human cells is determined by a Y-linked gene is provided by data demonstrating that male subjects with two Y chromosomes have higher antigen levels than male subjects with one y chromosome. The widespread evolutionary conservation of h-y antigen and its association with the y chromosome suggest that the antigen has a specific, crucial function. We surmise that this function is the differentiation of the embryonic gonad into whichever mature gonad, testis or ovary, typifies the heterogametic sex of each species. Of particular interest are individuals whose gonadal sex does not correspond to their somatic genotype. In the present article, we report positive results in the first case of 46,XY pure gonadal dysgenesis (Swyer's syndrome) to be typed for h-y antigen. This case suggests that the presence of h-y antigen may not be sufficient to complete masculinization of the embryonic mammalian gonad. Alternatively, a mutant gene may govern expression of a cell surface component which cross reacts with h-y antigen but which lacks the ability to function in the virilization of the gonad.
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16/19. Lack of X inactivation associated with maternal X isodisomy: evidence for a counting mechanism prior to X inactivation during human embryogenesis.

    We have previously reported functional disomy for X-linked genes in females with tiny ring X chromosomes and a phenotype significantly more abnormal than turner syndrome. In such cases the disomy results from failure of these X chromosomes to inactivate because they lack dna sequences essential for cis X inactivation. Here we describe a novel molecular mechanism for functional X disomy that is associated with maternal isodisomy. In this case, the severe mental retardation and multiple congenital abnormalities in a female with a mosaic 45,X/ 46,X,del(X)(q21.3-qter)/ 46X,r(X) karyotype are associated with overexpression of the genes within Xpter to Xq21.31 in many of her cells. Her normal X, ring X, and deleted linear X chromosomes originate from the same maternal x chromosome, and all are transcriptionally active. None expresses X inactive specific transcript (XIST), although the locus and region of the putative X inactivation center (XIC) are present on both normal and linear deleted X chromosomes. To our knowledge, this is the first report of a functional maternal X isodisomy, and the largest X chromosome to escape inactivation. In addition, these results (1) show that cis inactivation does not invariably occur in human females with two X chromosomes, even when the XIC region is present on both of them; (2) provide evidence for a critical time prior to the visible onset of X inactivation in the embryo when decisions about X inactivation are made; and (3) support the hypothesis that the x chromosome counting mechanism involves chromosomal imprinting, occurs prior to the onset of random inactivation, and is required for subsequent inactivation of the chromosome.
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17/19. Y to X translocation in man.

    Five new cases are added to the single published instance of Yq to Xp translocation(Xt) in man. It is shown that the anomaly can occur as a mutational event during meiosis, and can be inherited from a parent, but also that it can arise in a 47,XXY embryo. In individuals with 46,XXt karyotype the gonadal development, sexual differentiation, gonadal function and fertility are within the range of normal females. They do not present overt or discrete signs of virilisation. However, somatic stigmata, and more specifically short stature, are present in all patients. There is no uniform pattern of Xt inactivation which varies from random to apparently preferential inactivation. This phenomenon may be important for the better understanding of X-inactivation which for the Xt the authors believe is random but followed by differential proliferation of the resulting two types of cells.
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18/19. A patient with Simpson-Golabi-Behmel syndrome and hepatocellular carcinoma.

    Simpson-Golabi-Behmel syndrome (SGBS) is an X linked disorder characterised by pre- and postnatal overgrowth, coarse facial features, and visceral and skeletal abnormalities. Like other overgrowth syndromes, in the SGBS there is an increased risk for developing neoplasia, mainly embryonic, such as Wilms tumour. We report a 3 year old male patient with SGBS and hepatocellular carcinoma, a previously undescribed tumour associated with the syndrome.
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19/19. Case report: high fertilization rate in conventional in-vitro fertilization utilizing spermatozoa from an oligozoospermic subject presenting microdeletions of the y chromosome long arm.

    A case is reported in which a high fertilization rate was achieved by conventional in-vitro fertilization (IVF), using spermatozoa from an oligozoospermic man carrying a microdeletion of the long arm of the y chromosome. The patient presented with idiopathic infertility of 10 years duration; the fertility status of his wife was completely normal. After IVF, five out of eight oocytes retrieved showed normal fertilization and four showed normal embryo cleavage. Four embryos were transferred; however, pregnancy did not result. These results demonstrate that spermatozoa from oligozoospermic patients carrying a Yq microdeletion are fully competent in achieving capacitation, acrosome reaction and fertilizing ability during IVF. Therefore, although definitive conclusions cannot be made from a single case report, we suggest that Yq microdeletion analysis should be considered in oligozoospermic patients undergoing conventional IVF.
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