Prophylactic progesterone and preterm birth.

This review summarises the present knowledge of prophylactic progesterone and preterm birth. Preterm birth (less-than 37 weeks) is a leading cause of neonatal mortality and morbidity worldwide. The incidence varies globally but remains low in the Nordic countries (5-6%). Prediction and prevention are complicated due to diverse aetiology, but obstetric history and cervical length can improve prediction. Prophylactic vaginal progesterone initiated between 12 and 24 weeks of gestation is recommended to reduce preterm birth less-than 33-35 weeks in singleton pregnancies with a history of preterm birth or with a short cervix (less-than 25 mm) and can be considered for twin pregnancies with the same risk factors.

Endocrine, cardiac and neuropsychological aspects of adult congenital adrenal hyperplasia.

OBJECTIVE: To investigate the metabolic, cardiovascular, and neuropsychological phenotype, quality of life (QoL), and hormonal regulation in individuals with congenital adrenal hyperplasia (CAH), a group of autosomal recessive disorders characterized by impaired synthesis of cortisol in the adrenal cortex and, if untreated compensatory hyperandrogenism. CAH is associated with an increased cardiovascular and metabolic morbidity, possibly due to overtreatment with glucocorticoids, leading to weight gain, insulin resistance, and metabolic syndrome. DESIGN, PARTICIPANTS, MEASUREMENTS: Thirty-seven individuals with CAH and 33 age- and sex-matched controls were evaluated at a single centre at Aarhus University Hospital with echocardiography, electrocardiogram, 24-h blood pressure, biochemistry, anthropometrics, and autism spectrum, anxiety, depression, personality, cognitive failures, and QoL were assessed using questionnaires. RESULTS: CAH individuals had lower height than controls (170.5 vs. 182.9 cm in males and 160.2 vs. 170.1 cm in females, p < 0.01). Compared with female controls, females with CAH had higher haemoglobin (8.8 vs. 8.2 mmol/L, p = 0.003) and BMI (29.7 vs. 25.5 kg/m2, p = 0.006), reduced insulin sensitivity (HOMA-IR): 2.7 vs. 1.9, p = 0.018), prolonged E-wave deceleration time (193 vs. 174 cm, p = 0.015), and E/é ratios (5.4 vs. 4.5, p = 0.017), and lower self-reported QoL. Males with CAH had more cognitive complaints (p = 0.034) and higher autistic scores (19.9 vs. 14.9; p = 0.068) compared with male controls. More individuals with CAH than controls reported writing problems. CONCLUSION: A sex-specific comorbidity profile is evident in CAH, with females presenting with decreased metabolic and overall self-reported health, whereas males with CAH presented with increased cognitive complaints and autistic traits.

AMH and other markers of ovarian function in patients with Turner syndrome - a single center experience of transition from pediatric to gynecological follow up.

Turner syndrome (TS) is a chromosomal disorder that affects about 1 in 2500 female births and is characterized by the partial or complete absence of the second X chromosome. Depending on karyotype, TS is associated with primary ovarian insufficiency (POI). Approximately 50% of girls with a mosaic 45, X/46, XX karyotype may enter puberty spontaneously, but only 5-10% of women with TS achieve pregnancy without egg donation. In this review, we will evaluate the clinical use of markers of ovarian function in TS patients. Based on longitudinal studies of serum concentrations of reproductive hormones as well as ovarian morphology in healthy females and patients with TS, we will evaluate how they can be applied in a clinical setting. This is important when counseling patients and their families about future ovarian function essential for pubertal development and fertility. Furthermore, we will report on 20 years of experience of transition from pediatric to gynecological and adult endocrinological care in our center at Rigshospitalet, Copenhagen, Denmark.

The multi-omic landscape of sex chromosome abnormalities: current status and future directions.

Sex chromosome abnormalities (SCAs) are chromosomal disorders with either a complete or partial loss or gain of sex chromosomes. The most frequent SCAs include Turner syndrome (45,X), Klinefelter syndrome (47,XXY), Trisomy X syndrome (47,XXX), and Double Y syndrome (47,XYY). The phenotype seen in SCAs is highly variable and may not merely be due to the direct genomic imbalance from altered sex chromosome gene dosage but also due to additive alterations in gene networks and regulatory pathways across the genome as well as individual genetic modifiers. This review summarizes the current insight into the genomics of SCAs. In addition, future directions of research that can contribute to decipher the genomics of SCA are discussed such as single-cell omics, spatial transcriptomics, system biology thinking, human-induced pluripotent stem cells, and animal models, and how these data may be combined to bridge the gap between genomics and the clinical phenotype.

X chromosome dosage and the genetic impact across human tissues.

BACKGROUND: Sex chromosome aneuploidies (SCAs) give rise to a broad range of phenotypic traits and diseases. Previous studies based on peripheral blood samples have suggested the presence of ripple effects, caused by altered X chromosome number, affecting the methylome and transcriptome. Whether these alterations can be connected to disease-specific tissues, and thereby having clinical implication for the phenotype, remains to be elucidated. METHODS: We performed a comprehensive analysis of X chromosome number on the transcriptome and methylome in blood, fat, and muscle tissue from individuals with 45,X, 46,XX, 46,XY, and 47,XXY. RESULTS: X chromosome number affected the transcriptome and methylome globally across all chromosomes in a tissue-specific manner. Furthermore, 45,X and 47,XXY demonstrated a divergent pattern of gene expression and methylation, with overall gene downregulation and hypomethylation in 45,X and gene upregulation and hypermethylation in 47,XXY. In fat and muscle, a pronounced effect of sex was observed. We identified X chromosomal genes with an expression pattern different from what would be expected based on the number of X and Y chromosomes. Our data also indicate a regulatory function of Y chromosomal genes on X chromosomal genes. Fourteen X chromosomal genes were downregulated in 45,X and upregulated in 47,XXY, respectively, in all three tissues (AKAP17A, CD99, DHRSX, EIF2S3, GTPBP6, JPX, KDM6A, PP2R3B, PUDP, SLC25A6, TSIX, XIST, ZBED1, ZFX). These genes may be central in the epigenetic and genomic regulation of sex chromosome aneuploidies. CONCLUSION: We highlight a tissue-specific and complex effect of X chromosome number on the transcriptome and methylome, elucidating both shared and non-shared gene-regulatory mechanism between SCAs.

The Changing Face of Turner Syndrome.

Turner syndrome (TS) is a condition in females missing the second sex chromosome (45,X) or parts thereof. It is considered a rare genetic condition and is associated with a wide range of clinical stigmata, such as short stature, ovarian dysgenesis, delayed puberty and infertility, congenital malformations, endocrine disorders, including a range of autoimmune conditions and type 2 diabetes, and neurocognitive deficits. Morbidity and mortality are clearly increased compared with the general population and the average age at diagnosis is quite delayed. During recent years it has become clear that a multidisciplinary approach is necessary toward the patient with TS. A number of clinical advances has been implemented, and these are reviewed. Our understanding of the genomic architecture of TS is advancing rapidly, and these latest developments are reviewed and discussed. Several candidate genes, genomic pathways and mechanisms, including an altered transcriptome and epigenome, are also presented.

Sex chromosome aneuploidies give rise to changes in the circular RNA profile: A circular transcriptome-wide study of Turner and Klinefelter syndrome across different tissues.

Purpose: The landscape of circular RNAs (circRNAs), an important class of non-coding RNAs that regulate gene expression, has never been described in human disorders of sex chromosome aneuploidies. We profiled circRNAs in Turner syndrome females (45,X; TS) and Klinefelter syndrome males (47,XXY; KS) to investigate how circRNAs respond to a missing or an extra X chromosome. Methods: Samples of blood, muscle and fat were collected from individuals with TS (n = 33) and KS (n = 22) and from male (n = 16) and female (n = 44) controls. CircRNAs were identified using a combination of circRNA identification pipelines (CIRI2, CIRCexplorer2 and circRNA_finder). Results: Differential expression of circRNAs was observed throughout the genome in TS and KS, in all tissues. The host-genes from which several of these circRNAs were derived, were associated with known phenotypic traits. Furthermore, several differentially expressed circRNAs had the potential to capture micro RNAs that targeted protein-coding genes with altered expression in TS and KS. Conclusion: Sex chromosome aneuploidies introduce changes in the circRNA transcriptome, demonstrating that the genomic changes in these syndromes are more complex than hitherto thought. CircRNAs may help explain some of the genomic and phenotypic traits observed in these syndromes.

Turner Syndrome and Fertility.

Turner syndrome (TS) is tightly associated with hypergonadotropic hypogonadism and ovarian dysgenesis, typically resulting in infertility in the great majority of patients. Therefore females with TS are usually treated with female sex steroids from 11-12years of age until the normal age of natural menopause of around 53-54years of age. Infertility is rated among females with TS as a distressing concern and a detractor from a good quality of life. Options for motherhood for females with TS has expanded during recent years. Originally, only adoption was an option, unless of course for the small minority of TS females that still has ovarian function and are capable of achieving pregnancy through normal means. Oocyte donation has become the mainstream option in many countries and seems to work well, especially if patients have been treated with optimal estrogen and gestagen for a prolonged time before the intervention. It comes with an increased risk of cardiovascular complications and TS oocyte donation pregnancies are viewed as high risk pregnancies necessitating increased vigilance. Oocyte cryopreservation of own oocytes is also becoming an option in a select group of TS and has special challenges. Ovarian tissue cryopreservation is a promising new techniques that has been applied successfully in children with cancer. Currently, several trials are running around the world evaluating this techniques in TS. The genetics and genomics behind the ovarian dysgenesis seen in TS is not understood, but new studies have elucidated global changes in DNA methylation and RNA expression in blood from persons with TS and it is likely that similar changes are present in the ovaries. We still, however, need more thorough research to fully uncover the genetic background of ovarian failure in TS. Gene expression studies and methylation analysis from ovarian TS tissues still needs to be performed.

Women With Turner Syndrome Are Both Estrogen and Androgen Deficient: The Impact of Hormone Replacement Therapy.

CONTEXT: Women with Turner syndrome (TS) suffer from hypergonadotropic hypogonadism, causing a deficit in gonadal hormone secretion. As a consequence, these women are treated with estrogen from the age of 12 years, and later in combination with progesterone. However, androgens have been given less attention. OBJECTIVE: To assess sex hormone levels in women with TS, both those treated and those nontreated with hormone replacement therapy (HRT), and investigate the impact of HRT on sex hormone levels. METHODS: At Aarhus University Hospital, 99 women with TS were followed 3 times from August 2003 to February 2010. Seventeen were lost during follow-up. Control group 1 consisted of 68 healthy age-matched control women seen once during this period. Control group 2 consisted of 28 young, eumenorrheic women sampled 9 times throughout the same menstrual cycle. Serum concentrations of follicle-stimulating hormone (FSH), luteinizing hormone (LH), 17ß-estradiol, estrone sulfate, DHEAS, testosterone, free androgen index, androstenedione, 17-OH progesterone, and sex hormone-binding globulin (SHBG) were analyzed. RESULTS: All androgens, 17-OH progesterone, and sex hormone-binding globulin (SHBG) were 30% to 50% lower in TS compared with controls (P < 0.01). FSH, LH, and estrone sulfate were more than doubled in women with TS compared with controls (P < 0.02). Using principal component analysis, we describe a positive correlation between women with TS receiving HRT, elevated levels of SHBG, and decreased levels of androgens. CONCLUSION: The sex hormone profile in TS reveals a picture of androgen deficiency, aggravated further by HRT. Conventional HRT does not normalize estradiol levels in TS.

Disorders of the eye, ear, skin, and nervous system in women with Turner syndrome -a nationwide cohort study.

The literature about eye, ear, nose, skin, and nervous system disorders in women with Turner syndrome is equivocal. Impaired vision and hearing in women with Turner syndrome have been described, and case reports of Turner syndrome girls suffering from epilepsy have been published, but no large population-based-studies have explored the occurrence of any of these disorders. We aimed to investigate the risk of admission with disorders related to the eye, ear, nose, skin, and nervous system, compared with background females, and the impact of hormone replacement therapy on these conditions. 1,156 females with TS diagnosed during 1960-2014 were identified using the Danish Cytogenetic Central Registry and linked with personal-level data from the National Patient Registry and the Medication Statistics Registry. Statistics Denmark randomly identified 115,577 age-matched background females. Negative binomial regression was used to analyze hospital discharge diagnoses, reporting incidence rate ratios (IRR). Women with Turner syndrome have an increased risk of developing eye disorders (IRR 4.3 (95% CI 3.5-5.4), including cataract, glaucoma, ocular movement, and accommodation. The risk of ear disorders (IRR 35.0 (27.9-43.9)) and nose (IRR 2.2 (1.4-3.6)) was increased in women with Turner syndrome, due to otitis media, cholesteatoma, and hearing loss. Disorders of the nervous system such as epilepsy were increased IRR 6.2 (2.4-15.9), along with skin conditions IRR 2.2 (95%CI 1.7-2.7) like psoriasis, atopic dermatitis, and ingrown nails.

Increased occurrence of liver and gastrointestinal diseases and anaemia in women with Turner syndrome - a nationwide cohort study.

BACKGROUND: Liver and gastrointestinal diseases are frequent in women with Turner syndrome. However, their association with bleeding disorders, anaemia and the impact of hormone replacement therapy is unknown. AIMS: To investigate the risk of liver and gastrointestinal diseases, haemorrhage and anaemia in women with Turner syndrome compared with the female background population, and the long-term impact of hormone replacement therapy on these conditions. METHODS: One thousand one hundred and fifty-six women with Turner syndrome diagnosed during 1960-2014 were identified using the Danish Cytogenetic Central Registry and linked with personal-level data from the National Patient Registry and the Medication Statistics Registry. Statistics Denmark randomly identified 115 577 age-matched female controls. Negative binomial regression was used to analyse hospital discharge diagnoses. Medical prescriptions, mortality and the effect of hormone replacement therapy were estimated using stratified Cox regression. RESULTS: Liver disease increased 13-fold (IRR 12.9 (95% CI 5.8-28.8)), due to toxic liver disease (IRR 8.0 (95% CI 1.8-35.4)), liver insufficiency (IRR 6.7 (95% CI 1.7-26.9)), fibrosis/cirrhosis (IRR 16.5 (95% CI 2.2-122.1)) and unspecified liver disease (IRR 10.6 (95% CI 4.4-25.3)). Furthermore, presence of abnormal liver enzymes increased 12-fold (IRR 12.4 (95% CI 4.2-36.6)). The risk of gastrointestinal haemorrhage (IRR 3.4 (95% CI 1.8-6.2)), anaemia (IRR 3.2 (95% CI 2.0-5.0)) and coagulation disorders (IRR 2.9 (95% CI 1.1-7.1)) was increased. However these diagnoses were not associated with inflammatory bowel disease. Gastrointestinal mortality was increased three-fold (HR 3.1 (95% CI 1.5-6.2)), partly due to death by liver disease (HR 3.0 (95% CI 1.1-8.2)), gastrointestinal haemorrhage (HR 29.6 (95% CI 3.1-285.1)) and capillary malformations (HR 18.6 (95% CI 4.1-85.0)). There was no effect of hormone replacement therapy on gastrointestinal risk but a trend towards a beneficial impact on liver diseases. CONCLUSIONS: The risk of being diagnosed with liver disease was higher than previously reported. The occurrence of gastrointestinal haemorrhage and anaemia was increased in Turner syndrome. There was no effect of hormone replacement therapy on gastrointestinal risk but a trend towards a beneficial impact on liver diseases was detected.

Cancer occurrence in Turner syndrome and the effect of sex hormone substitution therapy.

OBJECTIVE: Although the overall risk of cancer is not increased in Turner syndrome, the pattern of cancer occurrence differs from the general population. We aim to describe the cancer morbidity pattern in Turner syndrome and evaluate the effect of long-term hormone replacement therapy (HRT). DESIGN: Nationwide epidemiological study. METHODS: 1156 females with Turner syndrome diagnosed during 1960-2014, were linked with data from the Danish National Patient Registry. Statistics Denmark randomly identified 115 578 female controls. Stratified Cox regression was used to analyze cancer morbidity, mortality and effect of HRT. RESULTS: Overall risk of cancer was not elevated (hazard ratio 1.04 (95% CI: 0.80-1.36)). The risk of skin cancer and benign skin neoplasms was two-fold increased, while the risk of breast cancer was decreased (hazard ratio 0.4 (0.2-0.9)). Turner syndrome (45,X) had a two- to five-fold increased risk of benign CNS tumors, colon and rectal cancers, benign skin neoplasms and skin cancer. Turner syndrome women with a 45,X/46,XX karyotype had an increased risk of tongue cancer. HRT had no impact on the risk of any cancer investigated in this study. CONCLUSIONS: The lack of one X chromosome might play a role in skin neoplasms, CNS tumors, colon and rectal cancers. The risk of breast cancer is lower than in the general population. Long-term HRT during the premenopausal age range seems not to exert a cancerous effect in Turner syndrome. Increased vigilance concerning specific types of cancer in Tuner syndrome harboring a 45,X karyotype is needed.

Coronary plaque burden in Turner syndrome a coronary computed tomography angiography study.

Turner syndrome (TS) is associated with coronary artery disease (CAD), an important cause of premature death in TS. However, the determinants of CAD in women with TS remain unknown. In a cross-sectional study design, 168 women without clinical evidence of CAD (115 with TS and 53 without TS) were assessed for the presence and volume of subclinical CAD using coronary CT angiography. Karyotype, the presence of congenital heart defects and conventional cardiovascular risk factors were also registered. Comparative analyses were performed (1) between women with and without TS and (2) in the TS group, between women with and without subclinical CAD. The prevalence of CAD, in crude and adjusted analyses, was not increased for women with TS (crude prevalence: 40 [35%] in TS vs. 25 [47%] in controls, p = 0.12). The volume of atherosclerosis was not higher in women with TS compared with controls (median and interquartile range 0 [0-92] in TS vs. 0 [0-81]mm3 in controls, p = 0.29). Among women with TS, women with subclinical CAD were older (46 ± 13 vs. 37 ± 11 years, p < 0.001), had higher blood pressure (systolic blood pressure 129 ± 16 vs. 121 ± 16 mmHg, p < 0.05) and were more frequently diagnosed with type 2 diabetes (5 [13%] vs. 2 [3%], p < 0.05). Karyotype or congenital heart defects were not associated with subclinical CAD. Some women with TS show early signs of CAD, however overall, not more than women without TS. Conventional cardiovascular risk factors were the principal determinants of CAD also in TS, and CAD prevention strategies should be observed.ClinicalTrial.gov Identifier: NCT01678261 ( https://clinicaltrials.gov/ct2/show/NCT01678261 ).

Epigenetics and genomics in Klinefelter syndrome.

Since the first description of Klinefelter syndrome (KS) was published in 1942 in The Journal of Clinical Endocrinology, large inter-individual variability in the phenotypic presentation has been demonstrated. However, our understanding of the global impact of the additional X chromosome on the genome remains an enigma. Evidence from the existing literature of KS indicates that not just one single genetic mechanism can explain the phenotype and the variable expressivity, but several mechanisms may be at play concurrently. In this review, we describe different genetic mechanisms and recent advances in the understanding of the genome, epigenome, and transcriptome of KS and the link to the phenotype and clinical heterogeneity. Future studies are needed to unite clinical data, genomic data, and basic research attempting to understand the genetics behind KS. Unraveling the genetics of KS will be of clinical relevance as it may enable the use of polygenic risk scores to predict future disease susceptibility and enable clinical risk stratification of KS patients in the future.

Sex Hormone Replacement Therapy in Turner Syndrome: Impact on Morbidity and Mortality.

CONTEXT: The long-term effects of female hormone replacement therapy (HRT) in Turner syndrome (TS) are unknown. OBJECTIVE: To examine morbidity, mortality and medicinal use in TS and the impact of HRT in 45,X women. DESIGN AND SETTING: National cohort study, following all TS individuals ever diagnosed in Denmark from 1977 to 2014. PATIENTS AND METHODS: In the Danish Cytogenetic Central Registry, we identified 1156 females diagnosed with TS from 1960 to 2014, and, subsequently, Statistics Denmark randomly identified 115 577 age-matched female controls. TS women and their matched controls were linked with person-level data from the National Patient Registry and the Medication Statistics Registry, and they were compared concerning mortality, hospitalizations, and medical prescriptions. Among 329 45,X women, 44 had never been HRT treated, and 285 had been treated at some point. HRT treated women were compared with untreated concerning mortality, hospitalizations, and medical prescriptions. RESULTS: Endocrine and cardiovascular mortality and morbidity were significantly increased in TS compared with the matched controls. Comparing HRT treated with nontreated 45,X women, we found a similar mortality (hazard ratio 0.83, 95% confidence interval 0.38-1.79). Among the HRT-treated 45,X women, we found a significantly lower use of antihypertensives, antidiabetics, and thyroid hormones and significantly reduced hospitalization rates for stroke and osteoporotic fractures. CONCLUSION: Women with TS have an increased overall mortality and morbidity. HRT seems to have a beneficial effect on endocrine conditions, hypertension, and stroke in women with 45,X karyotype, with no clear impact on mortality.

Care of adult women with Turner syndrome: the state of affairs in Germany.

In this commentary, we discuss the state of affairs concerning the clinical care of females with Turner syndrome (TS) in Germany. TS is a rare disease and new international guidelines describe an appropriate setup for optimal clinical care. Several countries have implemented a program with centralized adult Turner syndrome clinics, which are now found in France, Denmark, the Netherlands, Sweden, parts of England and possibly other countries, but hitherto not in Germany. Such an approach should ensure the availability of high quality multi-disciplinary care for all women with TS to be treated and to detect all the conditions that have been associated with TS, which typically appear at odd times during the lifetime of a female with TS. Care should be offered at no added cost for the patient, and treatment with relevant drugs should be available at reasonable cost for the individual patient. Currently, it is quite problematic that many female sex hormone preparations are not available at low cost in a number of countries. Additional problems include supply chain issue which lead to patients not being able to buy their usual drug for a certain period of time. We think it is timely that countries improve the care for individuals with rare conditions, such as TS.

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.

Turner syndrome: mechanisms and management.

Turner syndrome is a rare condition in women that is associated with either complete or partial loss of one X chromosome, often in mosaic karyotypes. Turner syndrome is associated with short stature, delayed puberty, ovarian dysgenesis, hypergonadotropic hypogonadism, infertility, congenital malformations of the heart, endocrine disorders such as type 1 and type 2 diabetes mellitus, osteoporosis and autoimmune disorders. Morbidity and mortality are increased in women with Turner syndrome compared with the general population and the involvement of multiple organs through all stages of life necessitates a multidisciplinary approach to care. Despite an often conspicuous phenotype, the diagnostic delay can be substantial and the average age at diagnosis is around 15 years of age. However, numerous important clinical advances have been achieved, covering all specialty fields involved in the care of girls and women with Turner syndrome. Here, we present an updated Review of Turner syndrome, covering advances in genetic and genomic mechanisms of disease, associated disorders and multidisciplinary approaches to patient management, including growth hormone therapy and hormone replacement therapy.

Epigenetics and genomics in Turner syndrome.

The pathogenesis of Turner syndrome (TS) and the genotype-phenotype relationship has been thoroughly investigated during the last decade. It has become evident that the phenotype seen in TS does not only depend on simple gene dosage as a result of X chromosome monosomy. The origin of TS specific comorbidities such as infertility, cardiac malformations, bone dysgenesis, and autoimmune diseases may depend on a complex relationship between genes as well as transcriptional and epigenetic factors affecting gene expression across the genome. Furthermore, two individuals with TS with the exact same karyotype may exhibit completely different traits, suggesting that no conventional genotype-phenotype relationship exists. Here, we review the different genetic mechanisms behind differential gene expression, and highlight potential key-genes essential to the comorbidities seen in TS and other X chromosome aneuploidy syndromes. KDM6A, important for germ cell development, has shown to be differentially expressed and methylated in Turner and Klinefelter syndrome across studies. Furthermore, TIMP1/TIMP3 genes seem to affect the prevalence of bicuspid aortic valve. KDM5C could play a role in the neurocognitive development of Turner and Klinefelter syndrome. However, further research is needed to elucidate the genetic mechanism behind the phenotypic variability and the different phenotypic traits seen in TS.

Changes in the cohort composition of turner syndrome and severe non-diagnosis of Klinefelter, 47,XXX and 47,XYY syndrome: a nationwide cohort study.

BACKGROUND: Knowledge on the prevalence of sex chromosome abnormalities (SCAs) is limited, and delayed diagnosis or non-diagnosis of SCAs are a continuous concern. We aimed to investigate change over time in incidence, prevalence and age at diagnosis among Turner syndrome (TS), Klinefelter syndrome (KS), Triple X syndrome (Triple X) and Double Y syndrome (Double Y). METHODS: This study is a nationwide cohort study in a public health care system. The Danish Cytogenetic Central Registry (DCCR) holds information on all karyotypes performed in Denmark since 1961. We identified all individuals in the DCCR with a relevant SCA during 1961-2014; TS: n = 1156; KS: n = 1235; Triple X: n = 197; and Double Y: n = 287. From Statistics Denmark, which holds an extensive collection of data on the Danish population, complete data concerning dates of death and migrations in and out of Denmark were retrieved for all individuals. RESULTS: The prevalence among newborns was as follows: TS: 59 per 100,000 females; KS: 57 per 100,000 males; Triple X: 11 per 100,000 females; and Double Y: 18 per 100,000 males. Compared with the expected number among newborns, all TS, 38% of KS, 13% of Triple X, and 18% of Double Y did eventually receive a diagnosis. The incidence of TS with other karyotypes than 45,X (P < 0.0001), KS (P = 0.02), and Double Y (P = 0.03) increased during the study period whereas the incidence of 45,X TS decreased (P = 0.0006). The incidence of Triple X was stable (P = 0.22). CONCLUSIONS: The prevalence of TS is higher than previously identified, and the karyotypic composition of the TS population is changing. Non-diagnosis is extensive among KS, Triple X and Double Y, whereas all TS seem to become diagnosed. The diagnostic activity has increased among TS with other karyotypes than 45,X as well as among KS and Double Y.