Analysis of genetic variability in Turner syndrome linked to long-term clinical features

Background

Women with Turner syndrome (TS) (45,X and related karyotypes) have an increased prevalence of conditions such as diabetes mellitus, obesity, hypothyroidism, autoimmunity, hypertension, and congenital cardiovascular anomalies (CCA). Whilst the risk of developing these co-morbidities may be partly related to haploinsufficiency of key genes on the X chromosome, other mechanisms may be involved. Improving our understanding of underlying processes is important to develop personalized approaches to management.

Objective

We investigated whether: 1) global genetic variability differs in women with TS, which might contribute to co-morbidities; 2) common variants in X genes - on the background of haploinsufficiency - are associated with phenotype (a "two-hit" hypothesis); 3) the previously reported association of autosomal TIMP3 variants with CCA can be replicated.

Methods

Whole exome sequencing was undertaken in leukocyte DNA from 134 adult women with TS and compared to 46,XX controls (n=23), 46,XX women with primary ovarian insufficiency (n=101), and 46,XY controls (n=11). 1) Variability in autosomal and X chromosome genes was analyzed for all individuals; 2) the relation between common X chromosome variants and the long-term phenotypes listed above was investigated in a subgroup of women with monosomy X; 3) TIMP3 variance was investigated in relation to CCA.

Results

Standard filtering identified 6,457,085 autosomal variants and 126,335 X chromosome variants for the entire cohort, whereas a somatic variant pipeline identified 16,223 autosomal and 477 X chromosome changes. 1) Overall exome variability of autosomal genes was similar in women with TS and control/comparison groups, whereas X chromosome variants were proportionate to the complement of X chromosome material; 2) when adjusted for multiple comparisons, no X chromosome gene/variants were strongly enriched in monosomy X women with key phenotypes compared to monosomy X women without these conditions, although several variants of interest emerged; 3) an association between TIMP3 22:32857305:C-T and CCA was found (CCA 13.6%; non-CCA 3.4%, p<0.02).

Conclusions

Women with TS do not have an excess of genetic variability in exome analysis. No obvious X-chromosome variants driving phenotype were found, but several possible genes/variants of interest emerged. A reported association between autosomal TIMP3 variance and congenital cardiac anomalies was replicated.

Challenges in developing a quantitative method of measuring breast development using 3D imaging: An example of a novel method for use in induced breast development with exogenous oestrogen

OBJECTIVE

Optimal breast development is an essential part of exogenous oestrogen treatment in females undergoing pubertal induction. We set out to develop a novel technique using three-dimensional (3D) imaging to determine change in breast volume that is applicable when no pre-existing breast contours are present.

DESIGN

A prospective observational study.

PATIENTS

The imaging methodology was developed using a single male subject to assess reproducibility and validity. The technique was then applied to 29 participants undergoing pubertal induction with exogenous oestradiol who were recruited from Paediatric Gynaecology and Reproductive Endocrinology clinics at University College London Hospital.

MEASUREMENTS

Breast images were taken using a 3D photographic system. Two images, taken at different times, were manually superimposed to produce a differential breast volume. The initial step of method development set out to show that volume change was not secondary to positioning artefact or image manipulation. This was established by using images of a male participant taken on different occasions. The technique was then used to assess reproducibility in participants undergoing pubertal induction treatment.

RESULTS

Good intraobserver reproducibility (intraclass correlation (ICC) 0.77) was demonstrated with static image manipulation. Validity of the imaging technique was established as there was no significant difference between the known reference volume produced by computer generated warping and that calculated by manual image manipulation. There was excellent intraobserver reproducibility for breast volume calculation in participants undergoing induced breast development (ICC 0.99).

CONCLUSIONS

3D imaging is a promising novel tool to provide quantitative breast volume assessment in individuals undergoing breast induction with exogenous oestradiol treatment.

Variability of response to early puberty induction demonstrated by transverse uterine diameter measurement and a novel method of 3D breast imaging

OBJECTIVE

Induction of puberty with exogenous oestrogen results in considerable variability in final uterine and breast volumes. We set out to quantify the variability of these two outcome measures with a view to establishing monitoring methods that could be used to individualise treatment protocols.

DESIGN

A prospective observational study.

PARTICIPANTS

Sixteen participants with pubertal delay and primary amenorrhoea, due to hypogonadism were recruited from paediatric gynaecology and endocrinology clinics at University College London Hospital. A standardised protocol of transdermal 17β oestradiol (17βE) was used (Evorel™), with a starting dose of 12.5 mcg increasing to 25 mcg (patch changed twice weekly) after 4 months. Follow up was every 2 months for a total of 8 months.

MEASUREMENTS

Uterine dimensions using ultrasound, oestradiol concentrations and breast development assessed by both Tanner staging and 3D photographic imaging.

RESULTS

After 8 months of treatment, the changes in oestradiol concentrations (0-174 pmol), uterine volume growth (4.4-16.4 ml) and breast volume (1.76-140.1 ml) varied greatly between individuals. Of uterine parameters, transverse uterine diameter was most closely associated with serum oestradiol levels at 8 months (beta standardised coefficient = 0.80, p = .001). Change in breast volume was associated with age of treatment initiation (beta standardised coefficient 0.55 p = .04).

CONCLUSIONS

We demonstrate variation in response to exogenous oestrogen, emphasising the necessity for individualised dose titration. In the absence of sensitive oestradiol assays, uterine transverse measurements may be used as a surrogate marker of oestrogen sensitivity to guide early dose adjustment. 3D breast imaging may provide a quantitative assessment of breast development to complement Tanner breast staging.

Relationship and sexual experiences in women with early-onset oestrogen deficiency: Comparison between women with Turner syndrome and premature ovarian insufficiency

OBJECTIVE

Age at first date and sexual intercourse have been observed to be delayed in women with Turner syndrome (TS), with delayed puberty being the main factor. We sought to assess relationship and sexual experiences comparing women with TS and premature ovarian insufficiency (POI).

DESIGN

Cross-sectional observational study.

PATIENTS

302 women with TS and 53 women with karyotypically normal POI (median age 33.0 [15.0-78.4] and 26.3 [17.8-52.3], respectively).

MEASUREMENTS

A self-reporting questionnaire was used to collect data on relationship and sexual experiences.

RESULTS

Women with TS were older than women with POI (P = .002). Compared to women with POI, a smaller proportion of women with TS had ever had vaginal sexual intercourse (VSI) (40 [78.4%] vs 169 [58.1%], respectively, P = .006) and women with TS exhibited a delay in the median age at first relationship and VSI (POI 19.3 ± 0.4 vs TS 22.2 ± 1.1, P = <.001). Start of oestrogen replacement therapy at ≤ 14 years of age compared with > 14 years did not result in earlier relationship and sexual debut. After adjusting for age and diagnosis, induction of puberty, as opposed to spontaneous puberty, was associated with a delay in the median age at first relationship and VSI and a reduced probability of having VSI (Hazard ratio = 0.44 [95% confidence interval: 0.32-0.60], P = <.001).

CONCLUSIONS

Turner syndrome and induction of puberty are associated with a reduced likelihood and a delay in relationship and sexual experiences. Women needing puberty induction and women with TS more than POI have a delayed mean age at first VSI compared to the general population.

Fracture rate in women with oestrogen deficiency - Comparison of Turner syndrome and premature ovarian insufficiency

OBJECTIVE

Women with early-onset oestrogen deficiency are at risk of reduced bone mineral density (BMD). We sought to assess fracture history and BMD in women with Turner syndrome (TS) and premature ovarian insufficiency (POI).

DESIGN

A cross-sectional observational study.

PATIENTS

Two hundred and sixty seven women with TS (median age 34.3 years) and 67 women with POI (median age 28.1 years).

MEASUREMENTS

A questionnaire was used to collect data on fracture history, co-morbidities and drug history including age at first oestrogen exposure. Clinical data included height, weight, serum vitamin D and hip and spine T-scores, which were adjusted for height and age. Fractures were subdivided into major osteoporotic fractures (MOF) and 'other' fracture types.

RESULTS

Overall fracture rate was similar in women with TS and POI (82 [30.5%] vs 22 [32.8%] respectively, P = .74). Compared to women with POI, those with TS had more fractures at MOF sites (30.2% vs 52.7%, P = .012) and fewer phalangeal fractures (27.9% vs 9.8%, P = .005). There was no difference in BMD between women who sustained a fracture compared to those who did not. Women with TS who fractured were more likely to suffer from hearing impairment compared to those with no fracture (62.2% vs 48.1%, P = .045).

CONCLUSIONS

TS is not associated with an overall excess risk of bone fracture. The higher rate of fractures at MOF sites in women with TS may be secondary to hearing impairment, thin cortical bone and abnormal bone remodelling.

Reduced uterine volume after induction of puberty in women with hypogonadism

OBJECTIVE

Adequate uterine growth is an essential component of pubertal induction with exogenous oestradiol in those with hypogonadism. Poor uterine development will render the individual vulnerable in the context of fertility. We assessed uterine size using ultrasound in those who had undergone pubertal induction treatment compared with a reference group who had experienced spontaneous puberty.

DESIGN

This is a single-centre, retrospective, cross-sectional study of women who underwent pubertal induction compared with a reference group.

PATIENTS

Ninety-five women with hypogonadism who had previously undergone pubertal induction and were receiving maintenance oestrogen replacement as adults were recruited: 48 women with Turner syndrome, 32 with premature ovarian insufficiency and 15 with gonadotrophin deficiency. The reference group consisted of 35 nulliparous women attending with male factor subfertility with a normal pelvis on ultrasonography.

MEASUREMENTS

Pelvic ultrasound was performed by a single observer. Uterine dimensions (total length, anterior-posterior (AP), transverse, uterine volume and fundal cervical AP ratio (FCR) measurements) were recorded. Clinical details were also recorded.

RESULTS

Those with hypogonadism had significantly reduced uterine dimensions compared with the reference group (uterine length 64 mm vs 71 mm P = <.05, uterine volume 28.9 mL vs 43.9 mL P = <.05). All women in the reference group attained a mature uterine configuration with a FCR >1, compared with 84% of those with hypogonadism (P = .01). A total of 24% and 48% of the diagnostic group had total uterine length and uterine volume measurements less than the 5th percentile of the reference group, respectively. In a subgroup of 22 women in whom serum oestradiol concentrations could be analysed, there was a positive correlation between this parameter and uterine volume.

CONCLUSION

Despite standard oestrogen therapy, uterine growth is often compromised in those with hypogonadism. Uterine health has historically been overlooked in pubertal induction protocols; however, with increasing options for fertility treatment, adequate uterine development is crucial. Given the variation in uterine size witnessed, a more tailored approach to treatment with regular monitoring of uterine dimensions should be advocated.

Effects of Estrogen Therapies on Outcomes in Turner Syndrome: Assessment of Induction of Puberty and Adult Estrogen Use

CONTEXT

Turner syndrome (TS) is often associated with delayed puberty. To induce puberty, estrogen is administered in incremental doses at an age determined by age of presentation. After puberty, various types of maintenance estrogen replacement therapy (ERT) are used.

OBJECTIVE

We sought associations between age of induction of puberty and type of ERT on adult health outcomes.

DESIGN

Health surveillance data included blood profiles, bone density, and blood pressure. We assessed interactions between these data and age at first estrogen exposure in women with primary amenorrhea. We also assessed these data according to ERT subgroups [combined oral contraceptive pill (OCP), oral estrogen (OE), and transdermal estradiol (TE)] using data from each of 6679 clinic visits, controlling for age, body mass index, and height.

SETTING

Adult TS clinic at University College London Hospital.

PATIENTS

Of 799 women with TS, 624 had primary amenorrhea and 599 had accurate maintenance ERT data.

MAIN OUTCOME MEASURES

Parameters of health surveillance derived from clinical guidelines.

RESULTS

Estrogen start age was negatively correlated with adult bone density (spine: r = -0.20 and hip: r = -0.022; P ≤ 0.001). OCP users had higher blood pressure and an adverse lipid profile compared with other ERT subgroups. TE was associated with elevated liver enzymes and hemoglobin A1c compared with OE (P ≤ 0.01).

CONCLUSIONS

An earlier age of induction of puberty may be beneficial for adult bone density. Given the high prevalence of hypertension in TS, the use of OCP for ERT should be limited. OE may be a benefit for steatohepatitis.

A critical assessment of case reports describing absent uterus in subjects with oestrogen deficiency

OBJECTIVE

The dual diagnosis of hypoplastic uterus in association with ovarian dysgenesis is regularly reported but the pathogenesis of the association is unclear. The uterus, however, may be invisible to all imaging modalities without at least six months of exogenous oestrogen exposure in complete ovarian failure. We assessed all available case reports in this category to estimate whether the apparent association between primary ovarian insufficiency or Turner syndrome and Mullerian agenesis can be largely accounted for by oestrogen deficiency.

DESIGN

A literature review of all cases in which an association between ovarian insufficiency or Turner syndrome and hypoplastic uterus has been reported.

PATIENTS

PubMed was searched for all case reports associated with relevant key terms. In total, 22 publications with a total of 25 patients were identified and reviewed; 14 subjects had the normal female karyotype (46,XX), and 11 subjects had Turner Syndrome.

MEASUREMENTS

Proportion of subjects who had been exposed to adequate oestrogen prior to the absent uterine diagnosis.

RESULTS

A diagnosis of absent uterus was made prior to exposure to exogenous oestrogen in 22/25 (88%) of subjects with primary hypogonadism including 14/14 females with normal karyotype and 8/11 females with Turner syndrome.

CONCLUSIONS

Oestrogen deficiency is a possible explanation for most subjects being reported as having Mullerian agenesis in association with Turner syndrome or primary ovarian insufficiency. In the presence of oestrogen deficiency, no conclusion can be made about the status of the uterus until adequate exposure to exogenous oestrogen has been completed and we suggest reassessment of the uterus when full adult dose has been reached towards the end of induction of puberty.

The Turner syndrome life course project: Karyotype-phenotype analyses across the lifespan

INTRODUCTION

Turner syndrome (TS) is associated with a variety of morbidities affecting nearly every body system, some of which increase in prevalence in adult life. The severity of clinical features in TS is roughly in parallel with the magnitude of the deficit of X-chromosome material. The aim of this study was to extend the established karyotype-phenotype relationships using data from a large adult cohort.

MATERIALS AND METHODS

Karyotypes were available in 656 women with TS. 611 of whom could be classified into five major groups within the cohort: 45,X; 45,X mosaicism (45,X/46,XX); isochromosome X (isochromosome Xq); mosaicism 45,X/46,XY and ring X. Continuous variables such as blood pressure and biochemical markers from clinic data were binarised allocating those in the upper quartile to represent at-risk individuals. With the exception of bone mineral density T-score for which the lower quartile was allocated as at risk. For comorbidities, initiation of formal treatment was recorded.

RESULTS

45,X/46,XX had considerably lower frequency of comorbidities compared to 45,X. The isochromosome group experienced similar outcomes to 45,X. Novel associations were found between the XY mosaic karyotype group and a decreased prevalence of thyroid disease and severe hearing loss. A previously unreported increased incidence of metabolic syndrome was noted within the ring chromosome subgroup.

CONCLUSIONS

Karyotype may play an important factor against stratifying risk of comorbidity in TS and should be taken into consideration when managing adults with TS. Further investigations of the isochromosome (Xq) and ring groups are necessary to further clarify their associations with comorbidities.