Partial deletion of an X chromosome

Ullrich-Turner syndrome associated with interstitial deletion of Xp11.4 leads to p22.31

The full phenotype of the Ullrich-Turner syndrome (UTS) is thought to be due to loss of the short arm of X. We report a 16-year-old girl with lack of secondary sexual development, amenorrhea, and short stature. She had thyroiditis and numerous other UTS manifestations and was found to have a non-mosaic 46,X,del(Xp) chromosome abnormality. Breakpoints occurred at p11.4 and p22.31, with a loss of the intervening segment.

Clinical and cytogenetic aspects of X-chromosome deletions

Karyotype/phenotype correlations in six non-mosaic patients with dysgenetic ovaries and partial deletions of the X-chromosome (three patients with short arm, and three with long arm deletions) are presented and the pertinent literature is analysed. It would appear that functioning ovarian tissue is present more often in patients with a short arm deletion than in those with a deleted long arm. This may represent a difference in the strength of two sets of controlling factors, but it can also be related to break point position. This in turn may be misinterpreted due to the difficulty in distinguishing between terminal and interstitial deletions in the long arm. Stature may be a heterochromatic effect, but if specific genetic factors influencing stature exist, then they would appear to be situated mostly on the short arm of the X-chromosome, although some 'statural determinants' occur also on the long arm and could be located rather close to the centromere. Deletions of the short arm of the X-chromosome were almost always associated with some features of the Turner phenotype, and could possibly be related to a gene dosage effect.

A synopsis of the human Y chromosome

Phenotypic features and functions known to depend on the presence of the Y chromosome or the H-Y antigen are discussed in relation to structural anomalies of the Y chromosome and other abnormalities of sexual and somatic development. Recent knowledge about molecular organization of constitutive heterochromatin in relation to the human Y is presented. An attempt is made at assigning different functions, genes and DNA sequences to different regions of the Y chromosome.

Analysis of DNA replication patterns of human fibroblast chromosomes: the replication map

A replication map of human fibroblast chromosomes from two diploid human female fibroblast lines, 46,XX and 46,X, del (X)(q13), was determined using the 'fluorescent plus Giemsa' (FPG) technique. Each chromosome was found to stain homogeneously dark when thymidine was incorporated for the entire S phase of that particular cell. As the duration of exposure to thymidine progressively decreased by increasing the incubation time in bromodeoxyuridine, the staining intensity of chromosomes decreased and, concurrently, gaps in the staining began to appear. These gaps coincide with R bands and represent the earliest areas to complete DNA synthesis. As these areas widen and increase in frequency, first Q and G bands appear, and finally C bands. Homologous X chromosomes were easily differentiated by either a comparison of the bands present or their staining intensity. The replication kinetics of the structurally abnormal heterocyclic X chromosome were very similar to those of the normal heterocyclic X chromosome. The X chromosome with deletion of a portion of the long arm was consistently late in replication.

Short-arm deletion of an X chromosome (45,XO/46,XX p--)

A 31-year-old female patient with short stature, signs of gonadal dysgenesis, and slight Turner signs is described with a mosaic 45,XO/46,XX del (X) (qter leads to p11) determined with trypsin Giemsa-banding and C-staining. BUdR incorporation indicated the deleted X to be late replicating.

Short arm deletion of an X chromosome, 46,XXp-

A 27-year-old patient of short stature with primary amenorrhea and other slight Turner signs showed a 46,XX,del(X) (qter leads to p11:) karyotype, identified by a combination of fluorescence and giemsa-banding technique. By BUdR incorporation the deleted X chromosome was shown to be the late replicating one.

Somatic stigmata of Turner's syndrome in a patient with 46,XXq-

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Xq- Turner's syndrome: reconsideration of hypothesis that Xp- causes somatic features in Turner's syndrome

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Apparent deletion of X chromosome in a prepuberal girl

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An unstable ring chromosome in a female infant with hypotonia, seizures, and retarded development

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