A strategic research alliance: Turner syndrome and sex differences

Sex chromosome constitution varies in the human population, both between the sexes (46,XX females and 46,XY males), and within the sexes (e.g., 45,X and 46,XX females, and 47,XXY and 46,XY males). Coincident with this genetic variation are numerous phenotypic differences between males and females, and individuals with sex chromosome aneuploidy. However, the molecular mechanisms by which sex chromosome constitution impacts phenotypes at the cellular, tissue, and organismal levels remain largely unexplored. Thus, emerges a fundamental question connecting the study of sex differences and sex chromosome aneuploidy syndromes: How does sex chromosome constitution influence phenotype? Here, we focus on Turner syndrome (TS), associated with the 45,X karyotype, and its synergies with the study of sex differences. We review findings from evolutionary studies of the sex chromosomes, which identified genes that are most likely to contribute to phenotypes as a result of variation in sex chromosome constitution. We then explore strategies for investigating the direct effects of the sex chromosomes, and the evidence for specific sex chromosome genes impacting phenotypes. In sum, we argue that integrating the study of TS with sex differences offers a mutually beneficial alliance to identify contributions of the sex chromosomes to human development, health, and disease.     

The mouse as a model of fundamental concepts related to Turner syndrome

Although XO mice do not show many of the overt phenotypic features of Turner syndrome (TS; 45,X or XO), mice and humans share different classes of genes on the X chromosome that are more or less likely to cause TS phenotypes. Based on the evolutionary history of the sex chromosomes, and the pattern of dosage balancing among sex chromosomal and autosomal genes in functional gene networks, it is possible to prioritize types of X genes for study as potential causes of features of TS. For example, X‐Y gene pairs are among the most interesting because of the convergent effects of X and Y genes that both are likely to prevent the effects of TS in XX and XY individuals. Many of the high‐priority genes are shared by mouse and human X chromosomes, but are easier to study in genetically tractable mouse models. Several mouse models, used primarily for the study of sex differences in physiology and disease, also produce XO mice that can be investigated to understand the effects of X monosomy. Using these models will lead to the identification of specific X genes that make a difference when present in one or two copies. These studies will help to achieve a better appreciation of the contribution of these specific X genes to the syndromic features of TS.     

Health care utilization and perceptions of health among adolescents and adults with Turner syndrome

We surveyed women aged 12 years and older who are members of the Turner Syndrome Society of the United States in regard to their health history, current health status, and health care utilization practices to identify the range of health problems and health care practices in this group. The mean age at diagnosis was 10.8 years, and an endocrinologist (41%) or pediatrician (35%) was most likely to make the initial diagnosis. Individuals over age 35 years were diagnosed with Turner syndrome and begun on estrogen replacement therapy at a significantly older age than those who were in younger age groups. Seventy-five percent of the respondents had required some type of surgical procedure, and 14% had been hospitalized within the previous year. Ninety-four percent of women rated their overall health as good to excellent, while 6% rated it fair to poor. In the 12–17-year age group, 89% of the young women were either currently taking or had previously taken growth hormone. The prevalence of major depressive symptoms was slightly higher than the general population for adolescents but similar to the general population for adults. For adult respondents, ratings of fair to poor health were significantly associated with increased outpatient visits. Growth hormone use was significantly associated with increased visits in the adolescent population. Based on these data, it appears that the clinical care of individuals with Turner syndrome has improved, but that they continue to have relatively high hospitalization rates and utilization of subspecialty services. Despite these health problems, most respondents demonstrated good adjustment as determined by standardized mental health measures.     

A mixed methods study of physical activity and quality of life in adolescents with Turner syndrome

Women with Turner syndrome (TS) have a high morbidity from both medical and psychological conditions with a negative impact on quality of life (QoL). Physical activity is a modifiable behavior shown to reduce risk for these chronic medical and mental health conditions and enhance QoL in other populations. Limited research suggests that adolescents and women with TS are less likely to engage in or enjoy physical activity than peers. This mixed methods study aimed to document physical activity levels in a sample of youth with TS and explore how factors unique to TS contribute to and are affected by physical activity. A cross‐sectional sample of 21 girls (12–21 years) with TS and their parents (n = 21) completed standardized questionnaires to quantify habitual physical activity (3‐day physical activity recall) and QoL (PROMIS) and participated in individual interviews focused on their experience with physical activity. Quantitative and qualitative results were synthesized using a phenomenological mixed methods approach. Results indicate that our sample engaged in less physical activity than peers and only 19% met recommendations for 1 hr per day of moderate‐to‐vigorous physical activity. Parents reported significant problems with peer relationships and psychological stress, and peer relationships scores correlated with physical activity. Reported barriers to physical activity included physical and psychosocial complications related to TS as well as unique developmental considerations specific to adolescence. Quantitative and qualitative results supported that structured fitness options embedded into routines enhanced activity levels. Results were compiled into specific recommendations for clinical care and areas of future research.     

Two fertile Turner women in a family

Two fertile women, mother and daughter, both presenting sex chromosomal mosaicism (45,X/46,XX/47,XXX and 45,X/46,Xr(X] are reported. The mechanisms through which a Turner women can eventually be fertile are discussed.     

Paternal sex chromosome aneuploidy as a possible origin of Turner syndrome in monozygotic twins: case report.

The meiotic or mitotic origin of most cases of Turner syndrome remains unknown, due to the difficulty in detecting hidden mosaicisms and to the lack of meiotic segregation studies. We have had the opportunity to study one pair of monozygotic twins concordant for Turner syndrome of paternal origin. The paternal origin of the single X chromosome was determined by polymerase chain reaction (PCR) amplification. No mosaicism was detected for the X or Y chromosome. In this case, a meiotic error during gametogenesis would be a likely origin of X monosomy. To determine if meiotic errors are more frequent in the father of these monozygotic twins concordant for Turner syndrome of paternal origin, molecular studies in spermatozoa were conducted to analyse sex chromosome numerical abnormalities. A total of 12520 sperm nuclei from the twins' father and 85338 sperm nuclei from eight normal donors were analysed using three-colour fluorescent in-situ hybridization. There were significant differences between the twins' father and control donors for XY disomy (0.22 versus 0.11%, P < 0.001) and total sex chromosome disomy (0.38 versus 0.21%, P < 0.001). These results could indicate an increased tendency to meiotic sex chromosome non-disjunction in the father of the Turner twins.     

High prevalence of cardiometabolic risk features in adolescents with 47,XXY/Klinefelter syndrome

Klinefelter syndrome (KS) occurs in 1:600 males and is associated with high morbidity and mortality due to diabetes and cardiovascular disease. Up to 50% of men with KS have metabolic syndrome, a cluster of features conferring increased risk for diabetes and cardiovascular disease. These cardiometabolic (CM) risk features have not been studied in adolescents with KS. The objective of this cohort study was to compare CM risk features in adolescents with KS to controls matched for sex, age, and BMI z score. Fifty males with KS (age 10–17 years) were well‐matched to male controls (n = 50) for age (14.0 ± 1.7 vs. 14.0 ± 1.5 years) and BMI z score (0.3 ± 1.3 vs. 0.4 ± 1.2). Three CM risk features were present in 30% of adolescents with KS compared to 12% of controls (RR 2.5, 95% CI 1.1–5.9, p = .048). The KS group had significantly lower HDL cholesterol (p = .006), higher triglycerides (p < .001), and greater waist circumference percentile (p < .001). Despite a normal BMI, the prevalence of CM risk features was very high in adolescents with KS, particularly for central adiposity and dyslipidemia. The pathophysiology of this metabolic profile independent of obesity needs further investigation to facilitate prevention of the high morbidity of cardiovascular disease and diabetes in this population. ClinicalTrials.gov identifiers: NCT01585831 and NCT02723305.     

High frequency of tissue-specific mosaicism in Turner syndrome patients

Interphase fluorescent studies of X chromosome aneuploidy in cultured and uncultured blood lymphocytes and oral mucosa epithelial cells using X centromere-specific DNA probe in addition to standard karyotype analysis were performed in 50 females with a clinical suspicion of Turner syndrome. All the patients were previously screened for the presence of 'hidden' Y chromosome mosaicism, using the primers DYZ3 and DYZ. The use of fluorescence in situ hybridization (FISH) analysis of interphase nuclei of tissues from different germ layers (lymphocytes from mesoderm and buccal epithelial cells from ectoderm) improves the accuracy of detection of low-level mosaicism. FISH studies on interphase nuclei revealed that 29% of patients with a pure form of monosomy X detected by metaphase analysis are, in fact, mosaics. The level of cells with the normal chromosomal constitution in lymphocytes of these cases as a rule was low, ranging from 3 to 18%, with an average of 7%. Two false-positive cases and one false-negative case of X monosomy mosaicism determined by standard cytogenetic approach were detected using FISH analysis. The majority of patients (92%) with mosaic form of Turner syndrome have considerable tissue-specific differences in levels of X aneuploidy. Our data indicate that in cases when mosaic aneuploidy with low-level frequency is questionable (approximately 10% and lower), the results of standard metaphase analysis should be supplemented with additional FISH studies of interphase nuclei. Tissue-specific differences in contents of different cell lines in the same patients point to the necessity of studying more than one tissue from each patient.     

Turner syndrome and meningioma: Support for a possible increased risk of neoplasia in Turner syndrome

Neoplasia is uncommon in Turner syndrome, although there is some evidence that brain tumors are more common in Turner syndrome patients than in the general population. We describe a woman with Turner syndrome (45,X) with a meningioma, in whom a second neoplasia, basal cell carcinomas of the scalp and nose, developed five years later in the absence of therapeutic radiation. Together with 7 cases of Turner syndrome with meningioma from a population-based survey in the United Kingdom, and 3 other isolated cases in the literature, we review this small number of patients for evidence of risk factors related to Turner syndrome, such as associated structural anomalies or prior treatment. We performed histological and fluorescent in situ hybridization (FISH) of 22q (NF2 locus) analyses of the meningeal tumor to search for possible molecular determinants. We are not able to prove causation between these two entities, but suggest that neoplasia may be a rare associated medical problem in Turner syndrome. Additional case reports and extension of population-based studies are needed.     

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.     

特纳综合征患者的染色体核型及临床表现特点

目的:分析特纳综合征(Turner syndrome,TS)患者的染色体核型及临床特点,以提高对此病的认识和诊疗水平,为早期发现特殊核型提供临床依据.方法:对确诊患者的临床表现、性激素水平、骨龄及染色体核型等进行分析和总结.结果:24例确诊为TS患者,首发临床表现均为身材矮小,有50％骨龄比实际年龄延后;50％具有TS典型体征,83.33％有促性腺激素水平明显偏高,50％未见卵巢组织;染色体核型分析提示33.33％为45,XO,50％为45X嵌合体,其余为其他类型;16.67％的患者有垂体瘤,8.33％有心血管结构异常,部分患者心电图有异常,8.33％有促甲状腺激素水平增高;PCR检测SRY基因均阴性,未发现Y染色质.结论:TS患者因细胞核型的不同,临床表现有所差异,且各种核型与临床表现有时并不完全相对应;对于矮小症女童,应常规行染色体核型分析;对于出现不能由传统核型分析鉴定的特殊染色体或者核型为45,XO的患者尽早行Y染色体检测,有利于发现异常的Y染色体,为是否需要预防性切除性腺提供依据.     

Familial Turner syndrome

A 28-year-old Turner female with secondary amenorrhea is described, who showed 45,X/46,X,del(Xp) mosaicism in her blood lymphocytes and a 46,X,del(Xp) karyotype only in her ovaries. 45,X/46,XX mosaicism was found in the patient's mother, who presented short stature, mild Turner dysmorphism and had a normal reproductive life-span. Phenotypic implications of the cytogenetic findings in the patients are discussed, and literature data on fertility in Turner syndrome are briefly reviewed.     

Turner综合征患儿标记染色体的来源研究

目的 了解Turner综合征患儿标记染色体的来源，以指导遗传咨询及治疗。方法 在染色体核型分析的基础上，对32例Turner综合征患者进行回顾性分析。对3例含有标记染色体的患儿进一步用荧光原位杂交技术研究标记染色体的来源。结果 3例含有标记染色体的Turner综合征患儿中，确定1例患儿的标记染色体来源于Y染色体，含有性别决定基因；1例来源于X染色体；另外1例未能确定其来源，该标记染色体可能来源于性染色体的其他片段或其他端着丝粒染色体。结论 Turner综合征患者的标记染色体大多来源于性染色体（X染色体、Y染色体），也可能来源于其他端着丝粒染色体。有必要同时应用X染色体和Y染色体特异性探针对Turner综合征患者进行标记染色体的荧光原位杂交分析，以明确标记染色体的来源。     

Measurement of body fat in Turner syndrome

Fourteen individuals with the Turner syndrome (gonadal dysgenesis with X chromosome chromosome abnormalities) were evaluated for obesity using hydrostatic weighing and skinfold measurements. While skinfold estimates of body fat correlated well with clinical impression, hydrostatic weighing appeared to falsely overestimate percent body fat. We suggest that reduced skeletal mass and/or occult lymphedema in Turner syndrome may invalidate the formula used to calculate percent body fat derived from hydrostatic weights. In this population and possibly in other disorders where skeletal mass is reduced from the normal, the use of hydrostatic weighing may be inappropriate.     

Detection and incidence of cryptic Y chromosome sequences in Turner syndrome patients

The presence of Y chromosome sequences in Turner syndrome (TS) patients may predispose them to gonadoblastoma formation with an estimated risk of 15–25%. The aim of this study was to determine the presence and the incidence of cryptic Y chromosome material in the genome of TS patients. The methodology involved a combination of polymerase chain reaction (PCR) and nested PCR followed by Southern blot analysis of three genes—the sex determining region Y (SRY), testis specific protein Y encoded (TSPY) and RNA binding motif protein (RBM) (previously designated as YRRM) and nine additional STSs spanning all seven intervals of the Y chromosome. The methodology has a high sensitivity as it detects one 46, XY cell among 10⁵ 46, XX cells. Reliability was ensured by taking several precautions to avoid false positive results. We report the results of screening 50 TS patients and the identification of cryptic Y chromosome material in 12 (24%) of them. Karyotypes were divided in four groups: 5 (23.8%) patients out of the 21 TS patients which have the 45, X karyotype (group A) also have cryptic Y sequences; none (0%) of the 7 patients who have karyotypes with anomalies on one of the X chromosomes have Y mosaicism (group B); 1 (6.3%) of the 16 patients with a mosaic karyotype have Y material (group C); and 6 (100%) out of 6 patients with a supernumerary marker chromosome (SMC) have Y chromosome sequences (group D). Nine of the 12 patients positive for cryptic Y material were recalled for a repeat study. Following new DNA extraction, molecular analysis was repeated and, in conjunction with fluorescent in situ hybridization (FISH) analysis using the Y centromeric specific probe Yc-2, confirmed the initial positive DNA findings. This study used a reliable and sensitive methodology to identify the presence of Y chromosome material in TS patients thus providing not only a better estimate of a patient's risk in developing either gonadoblastoma or another form of gonadal tumor but also the overall incidence of cryptic Y mosaicism.     

The state of Turner syndrome science: Are we on the threshold of discovery?

Turner syndrome (TS), a genetic condition affecting roughly 1 in 2,000 females, is caused by a complete or partial loss of the second sex chromosome. This special issue of the American Journal of Medical Genetics Part C is a collection of research and clinical care reviews in TS from an international group of physician and scientist leaders who attended the 2018 “Turner Network Resource Symposium: Turner Science in the 21st Century”, held in Arlington Virginia, July 15th‐17th, 2018. Both this special issue and the 2018 Symposium are fueled by two rationales. First, inadequate attention has been given to health and psychosocial problems in girls and women with TS; and second, that an understanding of TS might shed light on the role of sex chromosome dosage in common conditions such as heart disease and autoimmune disease. These seminars interweave multiple themes: the fundamental partnership between participants with rare diseases and researchers, new knowledge regarding clinical care in TS, and an understanding of the “molecular phenotype” of TS‐associated conditions.     

Recognition and management of adults with Turner syndrome: From the transition of adolescence through the senior years

Turner syndrome is recognized now as a syndrome familiar not only to pediatricians and pediatric specialists, medical geneticists, adult endocrinologists, and cardiologists, but also increasingly to primary care providers, internal medicine specialists, obstetricians, and reproductive medicine specialists. In addition, the care of women with Turner syndrome may involve social services, and various educational and neuropsychologic therapies. This article focuses on the recognition and management of Turner syndrome from adolescents in transition, through adulthood, and into another transition as older women. It can be viewed as an interpretation of recent international guidelines, complementary to those recommendations, and in some instances, an update. An attempt was made to provide an international perspective. Finally, the women and families who live with Turner syndrome and who inspired several sections, are themselves part of the broad readership that may benefit from this review.     

“Donating our bodies to science”: A discussion about autopsy and organ donation in Turner syndrome

At the Third Turner Resource Network Symposium, a working group presented the results of collaborative discussions about the importance of autopsy in Turner syndrome (TS). Considerable gaps in understanding the causes of death in TS can only be closed by more frequent death investigations and autopsies. The presentation included an overview of autopsy methods, strategies for utilizing autopsy, and biobanking to address research questions about TS, and the role of palliative care in the context of autopsy. This review highlights strategies to promote autopsy and tissue donation, culminating with an action plan to increase autopsy rates in the TS community.     

Essential hyperhidrosis in Turner syndrome

We describe two Turner patients suffering from severe essential hyperhidrosis. Since both disorders are rare (1 in 5000 live female births for Turner syndrome and approximately 1 in 1000 persons for essential hyperhidrosis), our finding of two patients with these disorders in a total of 150 essential hyperhidrosis patients may suggest that this association is more frequent in Turner syndrome than previously thought.