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924 result(s) for "Turner Syndrome - genetics"
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Radiological Features in Patients with Short Stature Homeobox-Containing (SHOX) Gene Deficiency and Turner Syndrome before and after 2 Years of GH Treatment
Background/Aims: The short stature homeobox-containing (SHOX) gene is one of many genes that regulate longitudinal growth. The SHOX deficiency (SHOX-D) phenotype, caused by intragenic or regulatory region defects, ranges from normal stature to mesomelic skeletal dysplasia. We investigated differences in radiological anomalies between patients with SHOX-D and Turner syndrome (TS) and the effect of 2 years of growth hormone (GH) treatment on these anomalies. Methods: Left hand/wrist, forearm and lower leg radiographs were assessed at baseline and after 2 years in children with genetically confirmed SHOX-D (GH-treated and untreated groups) and TS (GH-treated) in a randomised, controlled, multinational study. Results: Radiological anomalies of hand, wrist and forearm were common in SHOX-D and TS. Radial bowing appeared more prevalent in SHOX-D, while lower leg anomalies were more common in TS. There were no significant differences in radiological findings between GH-treated and untreated patients with SHOX-D after 2 years. Conclusion: GH treatment had no systematic effect on skeletal findings in SHOX-D, based on limited radiological differences between the GH-treated and untreated groups at 2 years. Bone age radiographs allow assessment of radiological signs indicating a potential diagnosis of SHOX-D and may lead to earlier genetic confirmation and initiation of GH therapy.
Prospective Study Confirms Oxandrolone-Associated Improvement in Height in Growth Hormone-Treated Adolescent Girls with Turner Syndrome
Background/Aims: Untreated girls with Turner syndrome (TS) have growth failure, and adult height is, on average, 20 cm less than predicted height. Treatment with growth hormone (GH) is now standard of care. The objective of this study was to investigate the benefit of adding oxandrolone (Ox) to GH in a long-term, randomized, placebo (Pl)-controlled prospective trial to near adult height in TS. Methods: Prospective, randomized, Pl-controlled study: 76 girls with TS (ages 10–14.9 years) were randomized to receive Ox (0.06 mg/kg/day) or Pl in combination with GH (0.35 mg/kg/week, daily) over 2 years. Auxologic data, breast and pubic hair Tanner stages, and hormone and lipid levels were measured. Subjects who chose to continue were followed in a 2-year double-blind extension, also received estrogen therapy (years 3, 4), and had dual-energy X-ray absorptiometry evaluation of bone density (years 3, 4). Results: At year 4, the change in absolute height and height SDS was greater in the GH/Ox versus GH/Pl group [26.2 ± 6.7 vs. 22.2 ± 5.1 cm, analysis of covariance (ANCOVA) p < 0.001; 1.8 ± 0.9 vs. 1.2 ± 0.7 standard deviation scores, ANCOVA p < 0.001]. Bone mineral density (BMD) of the wrist (0.51 ± 0.17 vs. 0.54 ± 0.05 g/cm 2 ) and spine (0.91 ± 0.34 vs. 0.96 ± 0.13 g/cm 2 ) in the GH/Ox versus GH/Pl groups was similar after 4 years. Breast development was slower in the GH/Ox versus GH/Pl group [year 4: Tanner stage 2.9 ±1.3 (Ox) vs. 4.1 ± 1.3 (Pl), p = 0.003], and menarche was approximately 1 year later. Conclusions: The addition of Ox to GH at mean age 12.0 ± 1.7 year augmented height gain after 4 years of treatment, slowed breast development and did not affect BMD in girls with TS. Whether initiation of Ox prior to initiation of pubertal development would optimize height gain without impeding breast development will require further study.
Sex differences in psychiatric disorders: what we can learn from sex chromosome aneuploidies
The study of sexual dimorphism in psychiatric and neurodevelopmental disorders is challenging due to the complex interplay of diverse biological, psychological, and social factors. Males are more susceptible to neurodevelopmental disorders including intellectual disability, autism spectrum disorder, and attention-deficit activity disorder. Conversely, after puberty, females are more prone to major depressive disorder and anxiety disorders compared to males. One major biological factor contributing to sex differences is the sex chromosomes. First, the X and Y chromosomes have unique and specific genetic effects as well as downstream gonadal effects. Second, males have one X chromosome and one Y chromosome, while females have two X chromosomes. Thus, sex chromosome constitution also differs between the sexes. Due to this complexity, determining genetic and downstream biological influences on sexual dimorphism in humans is challenging. Sex chromosome aneuploidies, such as Turner syndrome (X0) and Klinefelter syndrome (XXY), are common genetic conditions in humans. The study of individuals with sex chromosome aneuploidies provides a promising framework for studying sexual dimorphism in neurodevelopmental and psychiatric disorders. Here we will review and contrast four syndromes caused by variation in the number of sex chromosomes: Turner syndrome, Klinefelter syndrome, XYY syndrome, and XXX syndrome. Overall we describe an increased rate of attention-deficit hyperactivity disorder and autism spectrum disorder, along with the increased rates of major depressive disorder and anxiety disorders in one or more of these conditions. In addition to contributing unique insights about sexual dimorphism in neuropsychiatric disorders, awareness of the increased risk of neurodevelopmental and psychiatric disorders in sex chromosome aneuploidies can inform appropriate management of these common genetic disorders.
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.
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.
Mosaic Turner syndrome shows reduced penetrance in an adult population study
Purpose Many women with X chromosome aneuploidy undergo lifetime clinical monitoring for possible complications. However, ascertainment of cases in the clinic may mean that the penetrance has been overestimated. Methods We characterized the prevalence and phenotypic consequences of X chromosome aneuploidy in a population of 244,848 women over 40 years of age from UK Biobank, using single-nucleotide polymorphism (SNP) array data. Results We detected 30 women with 45,X; 186 with mosaic 45,X/46,XX; and 110 with 47,XXX. The prevalence of nonmosaic 45,X (12/100,000) and 47,XXX (45/100,000) was lower than expected, but was higher for mosaic 45,X/46,XX (76/100,000). The characteristics of women with 45,X were consistent with the characteristics of a clinically recognized Turner syndrome phenotype, including short stature and primary amenorrhea. In contrast, women with mosaic 45,X/46,XX were less short, had a normal reproductive lifespan and birth rate, and no reported cardiovascular complications. The phenotype of women with 47,XXX included taller stature (5.3 cm; SD = 5.52 cm; P = 5.8 × 10 −20 ) and earlier menopause age (5.12 years; SD = 5.1 years; P = 1.2 × 10 −14 ). Conclusion Our results suggest that the clinical management of women with 45,X/46,XX mosaicism should be minimal, particularly those identified incidentally.
Integrated functional genomic analyses of Klinefelter and Turner syndromes reveal global network effects of altered X chromosome dosage
In both Turner syndrome (TS) and Klinefelter syndrome (KS) copy number aberrations of the X chromosome lead to various developmental symptoms. We report a comparative analysis of TS vs. KS regarding differences at the genomic network level measured in primary samples by analyzing gene expression, DNA methylation, and chromatin conformation. X-chromosome inactivation (XCI) silences transcription from one X chromosome in female mammals, on which most genes are inactive, and some genes escape from XCI. In TS, almost all differentially expressed escape genes are downregulated but most differentially expressed inactive genes are upregulated. In KS, differentially expressed escape genes are upregulated while the majority of inactive genes appear unchanged. Interestingly, 94 differentially expressed genes (DEGs) overlapped between TS and female and KS and male comparisons; and these almost uniformly display expression changes into opposite directions. DEGs on the X chromosome and the autosomes are coexpressed in both syndromes, indicating that there are molecular ripple effects of the changes in X chromosome dosage. Six potential candidate genes (RPS4X, SEPT6, NKRF, CX0rf57, NAA10, and FLNA) for KS are identified on Xq, as well as candidate central genes on Xp for TS. Only promoters of inactive genes are differentially methylated in both syndromes while escape gene promoters remain unchanged. The intrachromosomal contact map of the X chromosome in TS exhibits the structure of an active X chromosome. The discovery of shared DEGs indicates the existence of common molecular mechanisms for gene regulation in TS and KS that transmit the gene dosage changes to the transcriptome.
Quantifying the polygenic contribution to variable expressivity in eleven rare genetic disorders
Rare genetic disorders (RGDs) often exhibit significant clinical variability among affected individuals, a disease characteristic termed variable expressivity. Recently, the aggregate effect of common variation, quantified as polygenic scores (PGSs), has emerged as an effective tool for predictions of disease risk and trait variation in the general population. Here, we measure the effect of PGSs on 11 RGDs including four sex-chromosome aneuploidies (47,XXX; 47,XXY; 47,XYY; 45,X) that affect height; two copy-number variant (CNV) disorders (16p11.2 deletions and duplications) and a Mendelian disease (melanocortin 4 receptor deficiency ( MC4R )) that affect BMI; and two Mendelian diseases affecting cholesterol: familial hypercholesterolemia (FH; LDLR and APOB ) and familial hypobetalipoproteinemia (FHBL; PCSK9 and APOB ). Our results demonstrate that common, polygenic factors of relevant complex traits frequently contribute to variable expressivity of RGDs and that PGSs may be a useful metric for predicting clinical severity in affected individuals and for risk stratification. Rare genetic disorders (RGDs) often exhibit significant clinical variability among affected individuals. Here, Oetjens et al. systematically study the contribution of common genetic variation to variable expressivity of RGDs and find it is frequently influenced by polygenic factors identified in genome-wide association studies of relevant traits.
Fertility preservation for genetic diseases leading to premature ovarian insufficiency (POI)
PurposeThe current review aims to summarize the data available concerning the applicability of fertility preservation techniques to genetic conditions at risk of premature ovarian insufficiency (POI).MethodsA literature review through the PubMed Database was carried out.ResultsAbout 10% of cases of POI is related to genetic diseases. The most frequent conditions associated with POI are Turner syndrome and fragile X pre-mutation; mutation of BRCA 1-2 genes and several other mutations and genetic syndromes have recently been highlighted, although they rarely occur. If a diagnosis is issued before POI onset, counseling on currently available fertility preservation techniques is advisable. In case of spontaneous menarche (this can occur variably depending on the mutation) established techniques like embryo or oocyte cryopreservation can be proposed, even if, in some cases, their effectiveness may be reduced by ovarian alterations connected to the mutation. Ovarian tissue cryopreservation has recently been defined as an established medical procedure for fertility preservation in young cancer patients and may be an option for prepubertal patients. However, it is still experimental in special populations with genetic diseases causing POI. New innovative experimental techniques, like in vitro maturation of immature oocytes (IVM) and vitro activation (IVA) of immature follicles on ovarian tissue, have shown limited but encouraging data and they will be probably available in the near future. For a correct risk-benefit evaluation, the following aspects should be considered: actual knowledge about the pathology-specific efficacy of the various techniques, the average age of onset of POI, the possible risks associated with the procedure in relation to the underlying pathology, the probability of spontaneous conception, as well as the health implications of a possible future pregnancy..ConclusionsFertility preservation techniques represent a crucial opportunity for patients with genetic risk of POI. Early diagnosis increases the chances to apply these techniques. No specific recommendations concerning fertility preservation for each genetic pathology are available, and clinicians should first counsel the patient and her relatives about known risks and benefits of the available techniques, both those established and those considered as experimental.
What microRNAs could tell us about the human X chromosome
MicroRNAs (miRNA) are small-non coding RNAs endowed with great regulatory power, thus playing key roles not only in almost all physiological pathways, but also in the pathogenesis of several diseases. Surprisingly, genomic distribution analysis revealed the highest density of miRNA sequences on the X chromosome; this evolutionary conserved mammalian feature equips females with a larger miRNA machinery than males. However, miRNAs contribution to some X-related conditions, properties or functions is still poorly explored. With the aim to support and focus research in the field, this review analyzes the literature and databases about X-linked miRNAs, trying to understand how miRNAs could contribute to emerging gender-biased functions and pathological mechanisms, such as immunity and cancer. A fine map of miRNA sequences on the X chromosome is reported, and their known functions are discussed; in addition, bioinformatics functional analyses of the whole X-linked miRNA targetome (predicted and validated) were performed. The emerging scenario points to different gaps in the knowledge that should be filled with future experimental investigations, also in terms of possible implications and pathological perspectives for X chromosome aneuploidy syndromes, such as Turner and Klinefelter syndromes.