[Factors predisposing to chromosome pathology].
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Abnormalities, Drug-Induced↗
Biomedical subjects
O Zuffardi
Publications and source records attributed to O Zuffardi.
H-Y antigen in human X-autosome translocations.
The distal segment of the X chromosome short arm (Xp223) escapes X-inactivation in the normal female. This was shown by the activity of three genes assigned to this segment, those for Xg, STS, and H-YB. In contrast, in cases with non-random X-inactivation due to structural aberration of one X chromosome, the genes for Xg and STS may undergo inactivation. In this article, it is shown that in X-autosome translocation, the H-YB gene which modifies the activity of H-Y antigen, may be inactivated as well. Evidence is presented that in these cases, expression of all three genes on Xp223 is concordant.
Animals↗
The role of Yp in sex determination: new evidence from X/Y translocations.
A 33-year-old man had azoospermia and tubular atrophy as in the Klinefelter syndrome but short stature. He had a 46,X,t(X/Y) (Xqter lead to p22.3::Yp11 lead to Yqter) translocation and was H-Y antigen-positive. This excludes one of the genes controlling H-Y antigen from the terminal portion of the short arm of the Y chromosome. This case and the two similar ones in the literature indicate that the proximal Yp portion is required for the differentiation of a male gonad. The pattern of X inactivation was random in the patient's fibroblasts, whereas in the lymphocytes the translocated chromosome was preferentially inactivated; comparison with other cases shows that the quantity of Y chromosome material involved in these translocations does not influence the X inactivation patterns. In the three cases with this dicentric translocation the X chromosome centromere is consistently the active one. Our case indicates that the choice of which centromere is inactivated is independent of the replication pattern of the X chromosome. Our patient and a few other relevant cases from the literature confirm that factors controlling height are located on the distal portion of Xp and of Yp.
Adult↗
Agenesis of corpus callosum, ocular, and skeletal anomalies (X-linked dominant Aicardi's syndrome) in a girl with balanced X/3 translocation.
Aicardi's syndrome, which is characterized by agenesis of the corpus callosum, specific chorioretinal abnormalities, and defects of vertebrae and ribs, is considered a probable X-linked dominant trait with male lethality. All features of this syndrome were seen in a girl with a de novo balanced X/3 translocation (46,X,t(X;3)(p22;q12)). It is hypothesized that the clinical picture is the consequence of chromosome breakage within the Aicardi locus. Then, unusual X-inactivation patterns in blood and fibroblasts of this patient can be explained by somatic selection against cells with the Aicardi phenotype.
Abnormalities, Multiple↗
Duplication of the short arm of chromosome 9. Analysis of five cases.
Five females with duplication of the short arm of one chromosome 9 are reported, one tetrasomic and four trisomic for 9p. The tetrasomy is due to an isochromosome 9p while the trisomies are due in one case to an intrachromosomal duplication present in lymphocytes but not in fibroblasts, two are secondary to translocations with chromosomes 22 and 13 respectively, and one is a mosaic with a cell line with an additional deleted chromosome 9 present in lymphocytes and fibroblasts. This analysis indicates that duplications 9p may result in impairment of ovarian function. The phenotypic differences between trisomy and tetrasomy 9p are discussed.
Abnormalities, Multiple↗
Gene mapping and serendipity. The locus for torticollis, keloids, cryptorchidism and renal dysplasia (31430, Mckusick) is at Xq28, distal to the G6PD locus.
The syndrome of torticollis, keloids, cryptorchidism and renal dysplasia was described by Goeminne (1968) in a large family, and listed as X-linked incomplete dominant by McKusick (1978; No. 31430). We mapped the locus on the long arm of the X chromosome at band q28 and distal to the G6PD locus. This was achieved by the chance discovery in the literature that two females, each with a balanced X/autosome translocation involving Xq28, had partial manifestation of the syndrome as was the case with the females in the larger family of Goeminne (1968).
Abnormalities, Multiple↗
[Yq deletion in fetal syndrome (author's transl)].
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Child↗
Preferential maternal derivation in inv dup(15): analysis of eight new cases.
Eight patients are reported with a de novo extra inverted duplicated chromosome 15. The abnormal chromosome was considered to be the same in all cases, but its precise delineation remained uncertain and was defined as either 15pter leads to 15q12::15q12 leads to 15pter or 15pter leads to 15q11::15q13 leads to 15pter. Analysis with various techniques of the satellite regions of the bisatellited chromosomes demonstrated maternal derivation in six and paternal derivation in one of the seven families. A non-sister chromatid exchange between the two homologous chromosomes 15 is considered a likely origin of the inv dup(15) in the cases with maternal derivation; in the only case of paternal derivation, however, the abnormal chromosome originated from one single chromosome 15. The clinical findings confirm that patients with inv dup(15) have mental and developmental retardation and are frequently affected by seizures, while severe physical malformations are absent.
Abnormalities, Multiple↗
The "cat eye syndrome": dicentric small marker chromosome probably derived from a no.22 (tetrasomy 22pter to q11) associated with a characteristic phenotype. Report of 11 patients and delineation of the clinical picture.
Eleven patients with the so-called Cat Eye syndrome are reported including a more detailed description of the original cases reported by Schmid and Fraccaro. All cases had, in addition to a normal karyotype, a small extra G-like chromosome which appeared to be an isochromosome for the juxtacentromeric region (pter to q11) of an acrocentric chromosome. None were mosaics. Clinical findings and further cytogenetic studies in a few cases suggest that these markers probably derive from a No. 22 chromosome. Characteristic features of the Cat Eye syndrome in these 11 patients and those reviewed from the literature are: ocular coloboma which may involve the iris, choroid and/or optic nerve, preauricular skin tags and/or pits which are probably the most consistent feature, congenital heart defect, anal atresia with a fistula, renal malformations such as unilateral absence, unilateral or bilateral hypoplasia, and cystic dysplasia, and antimongoloid position of eyes. Intelligence is usually low-normal, although moderate retardation is also seen. There is great variability in the clinical findings ranging from near normal to lethal malformations. Less frequent, but also characteristic findings are: microphthalmia, microtia with atresia of the external auditory canal, intrahepatic or extrahepatic biliary atresia and malrotation of the gut. Direct transmission of the marker from one generation to the other was observed in both sexes. In those families, there was considerable variability in the clinical findings between affected family members. These cases show that there is a bias of ascertainment for patients who have the more striking malformations, especially those with ocular coloboma and anal atresia, a combination which appears to be present in only a minority of cases. Many mildly affected patients probably remain undetected. It is proposed that the term Cat Eye syndrome should be applied only to cases with trisomy or tetrasomy of not more than 22pter to q11 and without additional duplication or deletion of another autosomal segment.
Adolescent↗
Trisomy 16q21 = to qter.
A case of trisomy 16q secondary to a paternal 16/18 translocation is described. A comparison of this case with the few other cases of trisomy 16q described in the literature indicates that trisomy for the long arm of chromosome 16 results in a severely affected phenotype and early death. Conversely, patient with trisomy 16p do not have gross abnormalities. We postulate that the prenatal lethality of full trisomy 16 is mainly due to the trisomy for the long arm.
Abnormalities, Multiple↗
Assignment by deletion mapping of the steroid sulfatase X-linked ichthyosis locus to Xp223.
A male child and his mother who are nullisomic and monosomic, respectively, for the distal portion of Xp because of an unbalanced X-Y translocation were tested for steroid sulfatase activity after clinical examination had yielded evidence for ichthyosis in the boy. Deficiency of steroid sulfatase was found in the male patient, while in his mother enzyme levels were in the heterozygous range. These results, based on cytogenetic evidence obtained with an elongation technique, indicate that the STS locus is at Xp 223.
Adult↗
Cd bands and centromeric function in dicentric chromosomes.
The Cd technique was applied to two cases of dicentric attached X chromosomes (XpXp and XqXq) and to cells from an established cell line of tumor origin (MaNo9) in which dicentrics with two active centromeres were present and dicentrics with one active and one inactive centromere. It was confirmed that the Cd technique discriminates between active and latent centromeres, and it was demonstrated that true dicentrics and dicentrics with one latent centromere can co-exist in the same cells. This indicates that the mechanism of centromere inactivation is a phenomenon that is specific to each chromosome and not generalized at the level of the individual cell.
Cell Line↗
Turner syndrome patients are H-Y positive.
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 to 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.
Cytotoxicity Tests, Immunologic↗
rDNA levels in infertile male carriers of Robertsonian translocations.
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Adult↗
Ring chromosome and latent centromeres.
A ring 12 chromosome was found in a male child with minor phenotypic alterations. No obvious loss of chromosome material was detected. Since there is no other case of a ring 12 in the literature, it was not possible to determine whether the phenotype was due to (invisible) terminal deletions or to karyotypic variation. In lymphocyte cultures 9% of the cells had either no or two rings, but the patient's RBC had normal activities of the enzymes lactate dehydrogenase B and peptidase B, whose loci are located on the proximal portions of 12p and 12q, respectively. Dicentric rings were found in 37 cells, and all had two active centromeres, in contrast with the relatively frequent finding of latent centromeres in translocated dicentric autosomes. Two latent centromeres were found in one tricentric "rod-shaped" open ring 12, probably derived from a tetracentric ring. It is postulated that latent centromeres are rare in ring chromosomes because, if consistent suppression of centromeres in excess of one took place at each duplication, rings with four, eight, or more centromeres would be formed rather frequently, which is not the case.
Cells, Cultured↗
Familial XX true hermaphroditism and the H-Y antigen.
Two 46,XX sibs, one of female, one of male gender, and both with ambiguous external genitalia and ovotestis, were H-Y positive. The mother was H-Y negative. It is assumed that the underlying mutation was transmitted by the father, resulting in an autosomal dominant mode of inheritance. The common origin and the nature of the mutation leading to XX sex reversal are discussed.
Adolescent↗
BSu restriction of DNA from cases exhibiting sex-chromosome abnormalities.
The restriction endonuclease BSu, an isoschizomer of the enzyme HaeIII, cleaves human DNA to yield classes of fragments that are characteristic of the DNA of individuals having a Y chromosome. The fragments concerned are therefore diagnostic of the presence of Y-chromosome DNA and have been studied here with the intention of confirming the origin of various translocations thought, on other grounds, to involve the Y. The absence of the fragments from DNA of a case exhibiting absence of the fluorecent region of Yq suggests that the DNA concerned maps predominantly to Yq. Normal gender in the absence of the BSu fragments indicates that they do not function in sex determination.
Adult↗
Nullisomy for the distal portion of Xp in a male child with a X/Y translocation.
An unbalanced X/Y translocation was found in a male child with malformed external genitalia and in his mother, who are respectively nullisomic and monosomic for the distal portion of Xp and have the translocated distal segment of Yq in excess. The loss of the distal portion of Xp is supposed to be the cause of the phenotypic abnormalities present in these subjects. The phenotype of our subjects is compared with those of the other cases of X/Y translocation described in the literature.
Dermatoglyphics↗