Monozygotic twins discordant for Ullrich-Turner syndrome

Ullrich-Turner syndrome occurred in one of a pair of female twins. The chromosome constitution of the affected twin was 45,X/46,XX and that of the normal twin 46,XX. Investigation of banded chromosomes, red cell antigens, HLA types, red cell enzymes, and serum proteins indicates monozygosity. The twins are discordant for height, pterygium colli, ovarian function, strabismus, dental eruption, external ear formation, hearing loss, and performance scores on the Wechsler Intelligence Test. All of these differences can be attributed to X monosomy in one cell line in the affected twin, presumably resulting from mitotic nondisjunction or anaphase lag early during embryonic development. Ten other pairs of apparently monozygotic twins discordant for the Ullrich-Turner syndrome have been reported previously, and the findings in these cases are reviewed.     

Monozygotic twins discordant for Ullrich-Turner syndrome

We describe 9-year-old twin girls who were thought to be monozygotic but who differed greatly in physical appearance and growth pattern. One twin had Ullrich-Turner syndrome (UTS), 45,X/46,XX mosaicism in peripheral blood, and only 45,X cells in skin fibroblasts. The phenotypically normal twin also had 45,X/46,XX mosaicism in blood but only 46,XX cells in cultured fibroblasts. Analysis of DNA marker patterns in blood lymphocytes and in skin fibroblasts confirmed monozygosity with a probability of 99.97%. This case is compared with other reported cases of discordance for UTS in twins. It is concluded that essentially all of the differences between the two twins can be explained by loss of an X chromosome early in embryogenesis with complete separation of 45,X and 46,XX cell lineages at the time of the twinning event. The presence of mosaicism in the peripheral blood of both twins is presumably due to anastomoses between the placentae resulting in a mixture of the two cell populations in the hematopoietic tissue.     

Ullrich-Turner syndrome with agenesis of the corpus callosum

We report on a 19-year-old woman with 45,X Ullrich-Turner syndrome who was severely mentally retarded and had hypotonia. Computer tomography (CT) scan showed agenesis of the corpus callosum. There have been few reports of gross developmental central nervous system (CNS) abnormalities in Ullrich-Turner syndrome. Only one case of Ullrich-Turner syndrome with agenesis of the corpus callosum has been reported. The high prenatal lethality of Ullrich-Turner syndrome may mask a CNS abnormality.     

Del (X)(p21.2) in a mother and two daughters with variable ovarian function

We report a family in which a woman with the mosaic karyotype 45,X/46,X,del(X)(p21.2) transmitted the deleted X chromosome to two daughters. The nature of the deletion was confirmed by fluorescent in situ hybridization (FISH). All three family members showed somatic Ullrich-Turner syndrome features, but only one daughter had ovarian failure. These observations have implications for the diagnosis of Ullrich-Turner syndrome and genotype/phenotype correlations of X chromosome deletions.     

Growth of heterokaryotic monozygotic twins discordant for Ullrich-Turner syndrome during the first years of life

The rare observation of different karyotypes in monozygotic (MZ) twins, i.e., heterokaryotic monozygosity, occurs due to chromosomal aberration in one of the twins after separation of the embryos. We report on the differences of heterokaryotic MZ Turkish twins who are discordant for Ullrich-Turner syndrome. Chromosomal analyses from peripheral lymphocytes revealed a 45,X/46,XX mosaicism in both twins. FISH analyses of buccal smears showed 99% of nuclei 45,X in twin A and 98% of nuclei 46,XX in twin B. These results are consistent with a non-mosaic 45,X and 46,XX karyotype, respectively. The girls showed a different growth pattern in the first years. As their genotype should be identical except for the number of X chromosomes, the difference in phenotype may be a pure result of loss of one X chromosome in the affected girl. Special interest is set on the spontaneous and growth hormone induced growth of the twins.     

Monozygotic twins with 45,X/46,XY mosaicism discordant for phenotypic sex

We report on two sets of monozygotic twins (MZTs) discordant for phenotypic sex ascertained at birth when the female twin was noted to have signs of the Ullrich-Turner syndrome. Cytogenetic investigations on the female of the first pair showed 45,X/46,XY mosaicism in lymphocytes but fibroblasts grown from two skin biopsies at separate sites and from gonadal tissue showed only 45,X cells. The male showed mosaicism in both blood lymphocytes and skin fibroblasts. In the second family, both twins also showed mosaicism in lymphocytes. The female had a 45,X karyotype in fibroblasts from skin and gonadal tissue, but in contrast to the first family, the male twin had a normal male karyotype in fibroblasts from skin biopsy and from connective tissue adjacent to the vas deferens. Discordant phenotypic sex in monozygotic twins is rare. As in our cases, the nine previously reported sets of MZTs all had mosaicism for sex chromosome abnormalities. A mitotic error leading to the loss of a Y chromosome prior to, accompanying, or following the twinning process would account for the reported combinations of karyotypes. Am. J. Med. Genet. 75:40–44, 1998. © 1998 Wiley-Liss, Inc.     

Follow-up of Ullrich's original patient with "Ullrich-Turner" syndrome

In 1930 Ullrich published the case of the prototype patient with what is now referred to as the Ullrich-Turner syndrome. In 1987 this patient was restudied at the age of 66 years. She permitted a cytogenetic study, a brief clinical evaluation, and reported about her life and adjustments to her condition. This patient had the striking findings of adults with the Ullrich-Turner syndrome and an unequivocal 45,X chromosome constitution in all cells examined, showing that she indeed has the Ullrich-Turner and not the Noonan syndrome. She reached a maximum height of 144.5 cm, had primary amenorrhea, failure of maturation of secondary sexual characteristics, and yet in many personal and professional ways had adjusted admirably to her condition.     

Monozygotic twins of discordant sex both with 45,X/46,X,idic(Y) mosaicism.

A female twin with short stature, unusual facial appearance, widely spaced nipples, and coarctation of the aorta was found to have a peripheral blood lymphocyte karyotype of 45,X(43%)/46,X,idic(Y)(p11). Her twin brother, also short with similar facial appearance, had the same mosaicism (40% 45,X). Cultured skin fibroblast studies showed discrepant karyotypes of 45,X (100%) in the girl and 45,X (78%)/46,X,idic(Y)(p11) in the boy. The mother and the father had normal chromosomes. Comparison of 27 biochemical markers yielded a likelihood of monozygosity of 0.9977. This report documents the occurrence of discordant phenotypic sex in monozygotic twins, involving gonadal dysgenesis with an abnormal dicentric Y, which presumably occurred de novo, followed by anaphase lag probably before the occurrence of twinning. Unequal distribution of the two resultant cell lines in various tissues of each twin could account for the development of the very different phenotypes, apparently normal boy and Ullrich-Turner girl.     

Chromosome 6q deletion and retinal cone dystrophy

In 1930 Ullrich published the case of the prototype patient with what is now referred to as the Ullrich-Turner syndrome. In 1987 this patient was restudied at the age of 66 years. She permitted a cytogenetic study, a brief clinical evaluation, and reported about her life and adjustments to her condition. This patient had the striking findings of adults with the Ullrich-Turner syndrome and an unequivocal 45,X chromosome constitution in all cells examined, showing that she indeed has the Ullrich-Turner and not the Noonan syndrome. She reached a maximum height of 144.5 cm, had primary amenorrhea, failure of maturation of secondary sexual characteristics, and yet in many personal and professional ways had adjusted admirably to her condition.     

Acro-renal polytopic defect

A female twin with short stature, unusual facial appearance, widely spaced nipples, and coarctation of the aorta was found to have a peripheral blood lymphocyte karyotype of 45, X(43%)/46, X, idic(Y)(p11). Her twin brother, also short with similar facial appearance, had the same mosaicism (40% 45, X). Cultured skin fibroblast studies showed discrepant karyotypes of 45, X (100%) in the girl and 45, X (78%)/46, X, idic(Y)(p11) in the boy. The mother and the father had normal chromosomes. Comparison of 27 biochemical markers yielded a likelihood of monozygosity of 0.9977. This report documents the occurrence of discordant phenotypic sex in monozygotic twins, involving gonadal dysgenesis with an abnormal dicentric Y, which presumably occurred de novo, followed by anaphase lag probably before the occurrence of twinning. Unequal distribution of the two resultant cell lines in various tissues of each twin could account for the development of the very different phenotypes, apparently normal boy and Ullrich-Turner girl.     

Ullrich-Turner phenotype with unusual manifestation in a patient with mosaicism 45,X/47,XX,+18

We report on a girl with Ullrich-Turner phenotype and 45,X/47,XX,+18 chromosomal mosaicism. Only two other patients with similar mosaicism have been reported, both girls with XY sex chromosome constitution. The face of the patient was highly asymmetric, the right side being almost normal, the left showing a typical Ullrich-Turner syndrome appearance. This clinical impression was strengthened by photographic doubling of both hemifaces. The patient had normal intelligence and did not show any stigmata of trisomy 18. © 1996 Wiley-Liss, Inc.     

Evidence of a normal mean telomere fragment length in patients with Ullrich-Turner syndrome.

Clinical and epidemiological studies suggest that premature ageing and increased morbidity and mortality is present in Ullrich-Turner syndrome. We studied telomere restriction fragment length (TRFL) in 30 women with Ullrich-Turner syndrome and 30 age-matched control women. All Turner women had the 45,X karyotype verified by karyotyping. We found no difference in the mean TRFL in the young age group (TS: 7011+/-521 vs C: 7285+/-917 bp, P = 0.3), or in the older age group (TS: 7357+/-573 vs C: 7221+/-621 bp, P = 0.6). In conclusion, our data suggest that Ullrich-Turner syndrome is not associated with excessive telomere loss, at least when studied in peripheral blood leucocytes, and thus quite different from other premature ageing syndromes.     

Survival of fetuses with 45,X: an instructive case and an hypothesis.

The high (greater than 95%) fetal loss rate of 45,X embryos and fetuses has led to the suggestion that fetal survival with this karyotype requires the presence of mosaicism. However, in many instances, even given a "mild Ullrich-Turner syndrome" phenotype, mosaicism is not detected. In a pregnancy studied for advanced maternal age, CVS cultured cells showed 65% 45,X and 35% 46,X,r(X). After termination, 2 fetal tissues showed 95% 45,X cells. It is suggested that infants with the 45,X karyotype likely had mosaicism for a structurally abnormal X or Y chromosome during embryogenesis, but the abnormal cell line disappeared prior to birth.     

Survival of fetuses with 45,X: An instructive case and an hypothesis

The high (> 95%) fetal loss rate of 45,X embryos and fetuses has led to the suggestion that fetal survival with this karyotype requires the presence of mosaicism. However, in many instances, even given a “mild Ullrich-Turner syndrome” phenotype, mosaicism is not detected. In a pregnancy studied for advanced maternal age, CVS cultured cells showed 65% 45,X and 35% 46,X,r(X). After termination, 2 fetal tissues showed 95% 45,X cells. It is suggested that infants with the 45,X karyotype likely had mosaicism for a structurally abnormal X or Y chromosome during embryogenesis, but the abnormal cell line disappeared prior to birth.     

FISH analysis helps identify low-level mosaicism in Ullrich-Turner syndrome patients.

PURPOSE: To search for X or Y chromosome mosaicism in 45,X individuals using fluorescent in situ hybridization (FISH). METHODS: From our series of 53 Ullrich-Turner syndrome patients, we used interphase FISH to evaluate the 19 who had an apparently nonmosaic 45,X karyotype with G-banding. RESULTS: Of those 19 patients, mosaicism was detected in seven (37%), five patients had an XX line, one had a monocentric isochromosome X, and one had a dicentric isochromosome X. No Y chromosome mosaic was identified. CONCLUSION: FISH analysis is a sensitive and cost-effective adjunct to karyotype analysis to identify sex chromosome mosaicism in UTS.     

45,X/46,X,+r(X) can have a distinct phenotype different from Ullrich-Turner syndrome.

We present a patient with 45,X/46,X,+r(X) mosaicism and lack of inactivation of either the normal or the ring X in the 46,X,+r(X) cells. The patient has mental retardation, syndactyly, minor facial anomalies, and a congenital heart defect. Although most patients with 45,X/46,X,+r(X) have the Ullrich-Turner syndrome, 2 previously described patients with this karyotype also had a distinct phenotype consisting of severe mental retardation, syndactyly, and abnormal face. The unusually severe phenotype in these patients was thought to be due to lack of X-inactivation of the ring X chromosome. The findings in our patient support this hypothesis.     

45,X/46,X, + r(X) can have a distinct phenotype different from Ullrich-Turner syndrome

We present a patient with 45,X/46,X, + r(X) mosaicism and lack of inactivation of either the normal or the ring X in the 46,X, + r(X) cells. The patient has mental retardation, syndactyly, minor facial anomalies, and a congenital heart defect. Although most patients with 45,X/46,X, + r(X) have the Ullrich-Turner syndrome, 2 previously described patients with this karyotype also had a distinct phenotype consisting of severe mental retardation, syndactyly, and abnormal face. The unusually severe phenotype in these patients was thought to be due to lack of X-inactivation of the ring X chromosome. The findings in our patient support this hypothesis.     

Dysgerminoma in a patient with the syndrome of gonadal dysgenesis with a 45,X karyotype

A 19-year-old woman with the Ullrich-Turner syndrome presented with a mass filling her entire pelvis. The tumor was a dysgerminoma. Only one other patient with a 45,X chromosome constitution has been reported with this form of malignancy.