CLINICAL AND CYTOGENETICAL STUDIES IN FEMALE GONADAL DYSGENESIS AND THEIR BEARING ON THE CAUSE OF TURNER'S SYNDROME

Human cytogenetics at Johns Hopkins Hospital, 1959-1962

An account is given of the introduction of human cytogenetics to the Division of Medical Genetics at Johns Hopkins Hospital, and the first 3 years' work of the chromosome diagnostic laboratory that was established at the time. Research on human sex chromosome disorders, including novel discoveries in the Turner and Klinefelter syndromes, is described together with original observations on chromosome behavior at mitosis. It is written in celebration of the centenary of the birth of Victor McKusick, the acknowledged father of Medical Genetics, who established the Division and had the foresight to ensure that it included the investigation of human chromosomes.

Turner Syndrome Systematic Review: Spontaneous Thelarche and Menarche Stratified by Karyotype

BACKGROUND

Girls with Turner syndrome (TS) have a high incidence of primary ovarian insufficiency. Recent data show rates of spontaneous thelarche (ST) of 38% and spontaneous menarche (SM) of 15-16%, with higher rates in those with mosaicism.

SUMMARY

We systematically reviewed the literature for evidence regarding rates of ST and SM in TS and evaluated rates based on the type of chromosomal mosaicism. We searched MEDLINE via PubMed, Embase, and the Cochrane Database of Controlled Trials. Reference lists were screened. Studies reporting outcomes of ST and SM in girls with TS, diagnosed by genetic analysis, were included. Data was collected regarding study design, cohort type, cohort age, the number of participants with ST and SM, the individual age at diagnosis of ST and SM, the mean age of patients with ST and SM, sample size, the number of participants with secondary amenorrhea, and karyotype. Key Messages: In total 2,699 patients were assessed for ST and 2,890 for SM from 43 articles. Overall the rates of ST were 32% (95% CI 26.4-38.9) and SM 20.8% (95% CI 19.3-22.4). Girls with X monosomy had the lowest rates of ST (i.e., 13%; 95% CI 8.7-19.7) and SM (i.e., 9.1%; 95% CI 7.3-11.3). Girls with 45,X/47,XXX had the highest rates of ST (i.e., 88.1%; 95% CI 62-97.1) and SM (i.e., 66.2%; 95% CI 49.3-79.6).

CONCLUSIONS

Rates of ST and SM differ by karyotype in TS. When counseling patients, the karyotype should strongly influence discussions regarding pubertal development and the future reproductive potential.

Widespread DNA hypomethylation and differential gene expression in Turner syndrome

Adults with 45,X monosomy (Turner syndrome) reflect a surviving minority since more than 99% of fetuses with 45,X monosomy die in utero. In adulthood 45,X monosomy is associated with increased morbidity and mortality, although strikingly heterogeneous with some individuals left untouched while others suffer from cardiovascular disease, autoimmune disease and infertility. The present study investigates the leukocyte DNAmethylation profile by using the 450K-Illumina Infinium assay and the leukocyte RNA-expression profile in 45,X monosomy compared with karyotypically normal female and male controls. We present results illustrating that genome wide X-chromosome RNA-expression profile, autosomal DNA-methylation profile, and the X-chromosome methylation profile clearly distinguish Turner syndrome from controls. Our results reveal genome wide hypomethylation with most differentially methylated positions showing a medium level of methylation. Contrary to previous studies, applying a single loci specific analysis at well-defined DNA loci, our results indicate that the hypomethylation extend to repetitive elements. We describe novel candidate genes that could be involved in comorbidity in TS and explain congenital urinary malformations (PRKX), premature ovarian failure (KDM6A), and aortic aneurysm formation (ZFYVE9 and TIMP1).

Phenotype/karyotype correlations of Y chromosome aneuploidy with emphasis on structural aberrations in postnatally diagnosed cases

Over 600 cases with a Y aneuploidy (other than non-mosaic 47,XYY) were reviewed for phenotype/karyotype correlations. Except for 93 prenatally diagnosed cases of mosaicism 45,X/46,XY (79 cases), 45,X/47,XYY (8 cases), and 45,X/46,XY/47,XYY (6 cases), all other cases were ascertained postnatally. Special emphasis was placed on structural abnormalities. This review includes 11 cases of 46,XYp-; 90 cases of 46,XYq- (52 cases non-mosaic; 38 cases 45,X mosaic); 34 cases of 46,X,r(Y) (9 cases non-mosaic and 25 cases 45,X mosaic); 8 cases of 46,X,i(Yp) (4 non-mosaic and 4 mosaic with 45,X); 12 cases of 46,X,i(Yq) (7 non-mosaic and 5 mosaic); 44 cases of 46,X,idic(Yq); 80 cases of 46,X, idic(Yp) (74 cases had breakpoints at Yq11 and 6 cases had breakpoints at Yq12); 130 cases of Y/autosome translocations (50 cases with a Y/A reciprocal translocation, 20 cases of Y/A translocation in 45,X males, 60 cases of Y/DP or Y/Gp translocations); 52 cases of Y/X translocations [47 cases with der(X); 4 cases with der(Y), and 1 case with 45,X with a der(X)], 7 cases of Y/Y translocations; 151 postnatally diagnosed cases of 45,X/46,XY; 14 postnatally diagnosed cases of 45,X/47,XYY; 18 cases of 45,X/46,XY/47,XYY; and 93 aforementioned prenatally diagnosed cases with a 45,X cell line. It is clear that in the absence of a 45,X cell line, the presence of an entire Yp or a region of it including SRY would lead to a male phenotype in an individual with a Y aneuploidy, whereas the lack of Yp invariably leads to a female phenotype with typical or atypical Ullrich-Turner syndrome (UTS). Once there is a 45,X cell line, regardless of whether there is Yp, Yq, or both Yp and Yq, or even a free Y chromosome in other cell line, there is an increased chance for that individual to be a phenotypic female with UTS manifestations or to have ambiguous external genitalia. This review once again shows a major difference in reported phenotypes between postnatally and prenatally diagnosed cases of 45,X/46,XY, 45,X/47,XYY, and 45,X/46,XY/47,XYY mosaicism. It appears that ascertainment bias can explain the fact that all known patients with postnatal diagnosis are phenotypically abnormal, while over 90% of prenatally diagnosed cases are reported to have a normal male phenotype. Further elucidation of major Y genes and their clinical significance can be expected in the rapidly expanding gene mapping projects. More, consequently better, phenotype/karyotype correlations can be anticipated at both the cytogenetic and the molecular level.

Normal growth and normalization of hypergonadotropic hypogonadism in atypical Turner syndrome (45,X/46,XX/47,XXX). Correlation of body height with distribution of cell lines

A comparison has been made of a case with 45,X/46,XX/47,XXX mosaicism with some 50 cases in the literature. A significant positive correlation was found between height standard deviation scores of mosaic patients from the literature and the frequency of cells with a normal chromosome constitution (n = 21, rs = 0.552, P < 0.01). In contrast, a significant negative correlation was seen between body height and the frequency of cells with a 45,X constitution (n = 21, rs = -0.594, P < 0.01). There was no significant correlation of height standard deviation score with the 47,XXX cell line (n = 21, rs = -0.353). A patient with a rare chromosomal mosaicism (45,X/46,XX/47,XXX) is described. The diagnosis was first made by chromosome analysis in amniotic cells. The patient showed no symptoms suggestive of Turner syndrome and growth followed the 75th height percentile. Basal and gonadotropin-releasing hormone stimulated gonadotropin levels normalized after age 4.8 years and did not subsequently return to hypergonadotropic levels. In blood lymphocytes, there was an increase in the frequency of cells with a normal chromosome constitution over 9 years. This in vivo cell selection is discussed. Chromosome analysis in skin fibroblasts showed the same triple mosaicism with a similar distribution of cell lines as in blood lymphocytes. In conclusion, statistical evidence was demonstrated that the severity of short stature is correlated with the distribution of cell lines in 45,X/46,XX/47,XXX mosaicism. This finding is of importance for the genetic counselling in cases of prenatal diagnosis of mosaic Turner syndrome.

Comparison of adult height between patients with XX and XY gonadal dysgenesis: support for a Y specific growth gene(s)

Adult height was compared between published cases of patients with XX gonadal dysgenesis (XXGD) and those with XY gonadal dysgenesis (XYGD). The mean adult height of XYGD patients (171.0 cm (SD 7.8), n = 27) was significantly greater than that of XXGD patients (164.4 cm (7.7), n = 27) (p less than 0.01). This finding supports the existence of a Y specific growth gene(s) which promotes statural growth independently of the effects of gonadal sex steroids.

Cytogenetic and molecular characterization of a small ring chromosome in the complex karyotype of a girl with Turner syndrome

Blood samples of an 8-year-old girl with Turner syndrome were examined using cytogenetic and molecular methods. Chromosomal analyses revealed a mosaic karyotype consisting of 25% 47,X,der(X), +r(X) and 75% 46,X,der(X) cells. Southern blot hybridizations with Y-specific DNA probes excluded a Y chromosomal origin of the small ring chromosome. In situ hybridization using DNA probe pXBR showed it to be X-derived. Examination of C-, Q-, and R-banding patterns indicated that the der(X) chromosome probably arose by a translocation event.

Otological disease in Turner's syndrome

1988 was the 50th anniversary of Henry Turner's original publication of the constellation of physical features which were subsequently recognized to be associated with a deprivation of X chromosomal material. The abnormalities of phenotype and karyotype are now eponymously associated with his name. Very many phenotype stigmata have now been recognized to be associated with Turner's syndrome. However, a survey of females with the syndrome revealed that they consider that a major disability associated with the abnormal karyotype results from otological disease and that this is poorly recognized as a significant feature of the syndrome. The incidence of otological disease in patients with this syndrome has been difficult to evaluate because of ascertainment bias and the apparent diversity of otological disorders previously reported. This report reviews the literature and details a study of otological disease and hearing impairment in a sample of Turner's syndrome females enrolled from a defined area.

Mortality ratios, life expectancy, and causes of death in patients with Turner's syndrome

In a prospective study of 156 female patients with Turner's syndrome who had survived infancy and been followed up for an average of 17 years there were 15 deaths. The expected mortality was 3.6. Sixteen of the patients had a congenital heart anomaly and five of the deaths occurred in this group. The 10 deaths in the remaining 140 were three times as many as expected. The reduction in life expectation was 12.5 years at age 1 year, 11 years at age 20, and 10 years at age 40. Deaths were due to a broad spectrum of diseases. In the sample as a whole there were eight deaths from diseases of the circulatory system. This number is significantly greater than expected, but four were due to congenital heart disease. When patients with congenital heart disease were omitted from the sample the mortality from circulatory disorders was not significantly increased. Within the category of circulatory disorders there were three deaths from dissection of the aorta, a number which is greatly in excess of the expected. Two of these patients had no previous evidence of heart disease.

Sex chromosome fragment in a phenotypically normal female. Significance of occult Y-related material

The authors report a 15-year-old short, nonvirilized, prepubertal female whose peripheral karyotype revealed a mosaicism in which 62 percent of the cells had a karyotype of 45X, and the other 38 percent had a karyotype of 46X plus a small unidentified marker chromosome. Since the authors were unable to determine from the karyotype whether this marker was derived from an X or a Y chromosome and because of the high risk for neoplasia in abnormal gonads containing Y material, she underwent surgical exploration, with removal of gonadal tissue. Microscopic examination of the streak gonads revealed a mixture of dysgenetic ovarian and testicular type tissues. The presence of testicular-like tubules strongly implied the presence of Y material in the genotype. Review of the literature reveals at least 19 similar cases in which presumed sex chromosomal markers or fragments were found in phenotypically normal females. Because of the risk of gonadal neoplasia in patients with occult Y chromosomal material, gonadectomy is indicated when the origin of the marker chromosome is uncertain.

Reduced fertility in women with X chromosome abnormality

One patient with the karyotype 46,X,del(X)(p11.23) and three patients with 45,X/46,XX mosaicism were fertile or showed normal ovarian function. The patient with the Xp deletion has two daughters with the same chromosomal abnormality. A study of these patients and of others reported in the literature indicated that fertility of patients with X chromosomal abnormality has a markedly shorter duration than fertility of the normal female. Menopause commonly occurred during the second and third decade of age. We suggest that such fertility is related to the rate of germ cell attrition and hypothesize that germ cell attrition in the human female is influenced by genes of multiple effect which are carried on the X chromosome. The more of these genes which are present the slower the rate of germ cell attrition.

Turner syndrome patients with a ring X chromosome

A patient with clinical features of Turner syndrome and a 45,X karyotype in repeated blood cultures was re-evaluated when she spontaneously entered puberty. A ring X cell line was found in a small proportion of fibroblasts. A review of 35 previously published ring X cases is presented. All are mosaic, the major cell line in most cases being 45,X. There is wide variation in the frequency with which the abnormalities associated with Turner syndrome are found in these patients. All have short stature. Some are sexually developed and fertile. Cardiovascular anomalies are uncommon. This phenotypic variation may have at least two causes: the size of the deleted portion at each end of the X chromosome, and the relative frequency and distribution of 45,X and 46,X,r(X) cell lines in various body tissues.

Dysgenesis of testicular and streak gonads in the syndrome of mixed gonadal dysgenesis: perspective derived from a clinicopathologic analysis of twenty-one cases

The clinical and pathologic aspects of 21 cases of mixed gonadal dysgenesis (MGD) were studied. The gonads in 15 patients consisted of a macroscopic testis and a streak gonad; six patients had variants, including two with bilateral testes and four with bilateral streak gonads or tumors. Functionally, the gonads were incompetent. Testes 1) failed to completely inhibit müllerian development, 2) failed to support full differentiation of mesonephric duct structures, 3) failed to adequately masculinize development of the external genitalia, or 4) often failed to mediate their own descent, resulting in asymmetry of the internal and external genitalia. None of the streak gonads mediated normal female adolescent development or fertility. Microscopic examination revealed that every gonad, regardless of its gross appearance, was morphologically abnormal. Although gonads with seminiferous tubules usually developed to a moderately advanced state, macroscopically resembling testes, the hilar zone remained architecturally disorganized; the cortex invariably lacked more than a rudimentary tunica albuginea or exhibited partial ovarian differentiation, sometimes even with a rare primordial follicle. Over time, the seminiferous tubules atrophied and hyalinized. Gonads that grossly resembled streak gonads were observed microscopically to be composed of a stroma resembling that of normal ovarian cortex. In patients more than several years of age, the entire complement of germ cells in streak gonads disappeared. It is suggested that patients with MGD be raised as females. Early removal of gonads will prevent the development of gonadoblastoma and dysgerminoma. If the uterus is retained and the patient is subsequently given exogenous estrogen, care should be taken to detect early any signs of the development of endometrial carcinoma or its precursor, to which these patients may be prone.

Gonadal and statural determinants on the X chromosome and their relationship to in vitro studies showing prolonged cell cycles in 45,X; 46,X,del(X)(p11); 46,X,del(X)(q13); and 46,X,del(X)(q22) fibroblasts

Correlation of clinical features with cytogenetic abnormalities for individuals showing deletions of the X short arm (Xp) or the X long arm (Xq) indicate the following: (1) both Xp and Xq are necessary to assure normal ovarian development, although (2) persisting ovarian function is not infrequently associated with either (del(X)(p11) or del(Xq)(13,21,22, or 24). (3) Ovarian determinants on Xp are localized to region Xp11, but determinants on Xq cannot be precisely localized. (4) Both Xp and Xq contain statural determinants, the former localized to region Xp21 leads to Xpter. Both cell generation time and phases of the cell cycle were studied to test the hypothesis that the short stature, intrauterine growth retardation, and high embryonic lethality of 45,X can be explained on the basis of intrinsic retardation of cell division (i.e., prolonged cell cycle). Cell generation times of four 45,X fibroblast lines were significantly longer than those of for normal diploid lines, a difference accounted for by a prolonged S phase. 46,X,del(X)(p11), 46,X,del(X)(q13), and 46,X,del(X)(q22) lines also showed increased cell generation times when compared to 46,XX lines.

Localisation of male determining factors in man: a thorough review of structural anomalies of the Y chromosome

It is widely accepted that male determination in man depends on the presence of a factor or factors on the Y chromosome. These factors may be localised within the Y chromosome through the study of structural anomalies of the Y. A thorough review of seven different structural anomalies of the Y is presented: dicentric Y chromosomes, Y isochromosomes, ring Y chromosomes, Y; autosome, Y;X, and Y;Y translocations, and Y deletions. The evidence from these studies indicates that a gene or genes on the short arm or the Y near the centromere play a crucial role in the development of the testes. A few studies indicate that one or more factors on the long arm of the Y may also influence testicular development. If such a factor is present on the long arm, then it too must be very near the centromere. The theory that separate genes independently control the initial development and maturation of the tests (on the long and short arms of the Y, respectively) may be premature. Recently proposed arguments in its favour are examined. Some evidence also indicates the presence of a fertility factor on the non-fluorescent segment of the long arm. Relevant information on the H-Y antigen is discussed.

Chromosomal and clinical findings in 110 females with Turner syndrome

One hundred and ten patients with abnormal karyotypes who were referred to the Department of Medical Genetics with the possible diagnosis of Turner syndrome were reviewed. The frequency of chromosomal abnormalities and clinical findings in the different chromosomal types are summarized.

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.

Controlling elements in the mouse X-chromosome. I. Interaction with the X-linked genes

The mouseX-chromosome controlling elements, detected by their influence on the position effect variegation caused by theX-autosome translocationT(1;X)Ct, have been found to modify the heterozygous phenotypes of twoX-linked genes. It is proposed thatX-inactivation can be incomplete, the level of inactivation or the frequency of cells in which inactivation is incomplete being dependent upon the ‘state’ of the controlling element located in theX. The data suggest that this is a consequence of a reversal, or partial reversal, of inactivation of theXas a whole in some cells rather than a vairable spread of inactivation along the length of theX.

[On a case of Turner's syndrome with unusual chromosome findings (partial mosaicism)]

Clinical and chromosomal studies of a case of gonadal dysgenesis. The patient presented primary amenorrhea, rudimentary uterus, ipoplastic tubes and gonadad streak. No Barr bodies or drumsticks were found, and the chromosome analysis revealed a mosaic of the type XO/X + centric fragment. The pertinent literature is reviewed, and attention is drawn to the possible existence of a secretion of the steroid type in the Leydig-like cells present in the gonadal streak.