Bone fragility in Turner syndrome: Fracture prevalence and risk factors determined by a national patient survey

Transition from pediatric to adult care in patients with Turner syndrome in Italy: a consensus statement by the TRAMITI project

PURPOSE

Transition from pediatric to adult care is associated with significant challenges in patients with Turner syndrome (TS). The objective of the TRansition Age Management In Turner syndrome in Italy (TRAMITI) project was to improve the care provided to patients with TS by harnessing the knowledge and expertise of various Italian centers through a Delphi-like consensus process.

METHODS

A panel of 15 physicians and 1 psychologist discussed 4 key domains: transition and referral, sexual and bone health and oncological risks, social and psychological aspects and systemic and metabolic disorders.

RESULTS

A total of 41 consensus statements were drafted. The transition from pediatric to adult care is a critical period for patients with TS, necessitating tailored approaches and early disclosure of the diagnosis to promote self-reliance and healthcare autonomy. Fertility preservation and bone health strategies are recommended to mitigate long-term complications, and psychiatric evaluations are recommended to address the increased prevalence of anxiety and depression. The consensus also addresses the heightened risk of metabolic, cardiovascular and autoimmune disorders in patients with TS; regular screenings and interventions are advised to manage these conditions effectively. In addition, cardiac abnormalities, including aortic dissections, require regular monitoring and early surgical intervention if certain criteria are met.

CONCLUSIONS

The TRAMITI consensus statement provides valuable insights and evidence-based recommendations to guide healthcare practitioners in delivering comprehensive and patient-centered care for patients with TS. By addressing the complex medical and psychosocial aspects of the condition, this consensus aims to enhance TS management and improve the overall well-being and long-term outcomes of these individuals.

Organ Abnormalities Caused by Turner Syndrome

Turner syndrome (TS), a genetic disorder due to incomplete dosage compensation of X-linked genes, affects multiple organ systems, leading to hypogonadotropic hypogonadism, short stature, cardiovascular and vascular abnormalities, liver disease, renal abnormalities, brain abnormalities, and skeletal problems. Patients with TS experience premature ovarian failure with a rapid decline in ovarian function caused by germ cell depletion, and pregnancies carry a high risk of adverse maternal and fetal outcomes. Aortic abnormalities, heart defects, obesity, hypertension, and liver abnormalities, such as steatosis, steatohepatitis, biliary involvement, liver cirrhosis, and nodular regenerative hyperplasia, are commonly observed in patients with TS. The SHOX gene plays a crucial role in short stature and abnormal skeletal phenotype in patients with TS. Abnormal structure formation of the ureter and kidney is also common in patients with TS, and a non-mosaic 45,X karyotype is significantly associated with horseshoe kidneys. TS also affects brain structure and function. In this review, we explore various phenotypic and disease manifestations of TS in different organs, including the reproductive system, cardiovascular system, liver, kidneys, brain, and skeletal system.

Normal bone density but altered geometry in girls with Turner syndrome

OBJECTIVES

Data on bone density and stability in Turner syndrome (TS) are contradictory. A confounding factor for interpretation is short stature. The aim was to measure bone density, geometry and stability in girls with TS compared to idiopathic short stature (ISS).

METHODS

From 1999 to 2008, 59 girls with TS (35 prepubertal) were evaluated by pQCT. Mean age was 8.9 in prepubertal and 17.3 years in adolescent girls. Mean height was -3.1 and -1.8 SDS in prepubertal treatment-free and in adolescent, formerly rhGH-treated girls. For comparison, 18 prepubertal ISS girls were studied (age 7.7 years; height -3.3 SDS). Examination of radius with pQCT (XCT 2000). Cortical (CD) and trabecular density (TD), total bone area (TBA), cortical area (CA), cortical thickness, muscle area and strength strain index (SSI) were determined and compared with height related references.

RESULTS

In prepubertal girls with TS, TD and CD were normal (0.55 and 0.90 SDS) and comparable to ISS (0.95 and 1.53 SDS). TBA was greater in girls with TS than in ISS (0.87 vs. -0.33 SDS) whereas CA was similar (1.48 vs. 1.43 SDS). The SSI was comparable (1.61 vs. 1.56 SDS). Adolescent girls with TS showed similar results with a TD of 0.48 SDS, a CD of -0.32, TBA of 1.99, a CA of -0.05 and an SSI of 0.88 SDS.

CONCLUSIONS

The observations are consistent with normal bone density and stability but altered bone geometry in prepubertal and substituted adolescent girls with TS. This peculiarity may reflect SHOX deficiency. We therefore think that timely and adequate estrogen substitution could prevent bone loss in TS.

Bone Mineral Density and Current Bone Health Screening Practices in Friedreich's Ataxia

Introduction

Friedreich's Ataxia (FRDA) is a progressive neurological disorder caused by mutations in both alleles of the frataxin (FXN) gene. Impaired bone health is a complication of other disorders affecting mobility, but there is little information regarding bone health in FRDA.

Methods

Dual energy X-ray absorptiometry (DXA) scan-based assessments of areal bone mineral density (aBMD) in individuals with FRDA were abstracted from four studies at the Children's Hospital of Philadelphia (CHOP). Disease outcomes, including the modified FRDA Rating Scale (mFARS), were abstracted from the FRDA Clinical Outcomes Measures Study (FACOMS), a longitudinal natural history study. A survey regarding bone health and fractures was sent to individuals in FACOMS-CHOP.

Results

Adults with FRDA (n = 24) have lower mean whole body (WB) (-0.45 vs. 0.33, p = 0.008) and femoral neck (FN) (-0.71 vs. 0.004, p = 0.02) aBMD Z-scores than healthy controls (n = 24). Children with FRDA (n = 10) have a lower WB-less-head (-2.2 vs. 0.19, p < 0.0001) and FN (-1.1 vs. 0.04, p = 0.01) aBMD than a reference population (n = 30). In adults, lower FN aBMD correlated with functional disease severity, as reflected by mFARS (R = -0.56, p = 0.04). Of 137 survey respondents (median age 27 y, 50% female), 70 (51%) reported using wheelchairs as their primary ambulatory device: of these, 20 (29%) reported a history of potentially pathologic fracture and 11 (16%) had undergone DXA scans.

Conclusions

Low aBMD is prevalent in FRDA, but few of even the highest risk individuals are undergoing screening. Our findings highlight potential missed opportunities for the screening and treatment of low aBMD in FRDA.

Secondary Osteoporosis

Osteoporosis is a global public health problem, with fractures contributing to significant morbidity and mortality. Although postmenopausal osteoporosis is most common, up to 30% of postmenopausal women, > 50% of premenopausal women, and between 50% and 80% of men have secondary osteoporosis. Exclusion of secondary causes is important, as treatment of such patients often commences by treating the underlying condition. These are varied but often neglected, ranging from endocrine to chronic inflammatory and genetic conditions. General screening is recommended for all patients with osteoporosis, with advanced investigations reserved for premenopausal women and men aged < 50 years, for older patients in whom classical risk factors for osteoporosis are absent, and for all patients with the lowest bone mass (Z-score ≤ -2). The response of secondary osteoporosis to conventional anti-osteoporosis therapy may be inadequate if the underlying condition is unrecognized and untreated. Bone densitometry, using dual-energy x-ray absorptiometry, may underestimate fracture risk in some chronic diseases, including glucocorticoid-induced osteoporosis, type 2 diabetes, and obesity, and may overestimate fracture risk in others (eg, Turner syndrome). FRAX and trabecular bone score may provide additional information regarding fracture risk in secondary osteoporosis, but their use is limited to adults aged ≥ 40 years and ≥ 50 years, respectively. In addition, FRAX requires adjustment in some chronic conditions, such as glucocorticoid use, type 2 diabetes, and HIV. In most conditions, evidence for antiresorptive or anabolic therapy is limited to increases in bone mass. Current osteoporosis management guidelines also neglect secondary osteoporosis and these existing evidence gaps are discussed.

Musculoskeletal Health in Premature Ovarian Insufficiency. Part Two: Bone

Accelerated bone loss and muscle loss coexist in women with premature ovarian insufficiency (POI), but there are significant gaps in our understanding of musculoskeletal health in POI. This review describes estrogen signaling in bone and its role in skeletal health and disease. Possible mechanisms contributing to bone loss in different forms of POI and current evidence regarding the utility of available diagnostic tests and therapeutic options are also discussed. A literature review from January 2000 to March 2020 was conducted to identify relevant studies. Women with POI experience significant deterioration in musculoskeletal health due to the loss of protective effects of estrogen. In bone, loss of bone mineral density (BMD) and compromised bone quality result in increased fracture risk; however, tools to assess bone quality such as trabecular bone score (TBS) need to be validated in this population. Timely initiation of HRT is recommended to minimize the deleterious effects of estrogen deficiency on bone in the absence of contraindications; however, the ideal estrogen replacement regimen remains unknown. POI is associated with compromised bone health, regardless of the etiology. Ongoing research is warranted to refine our management strategies to preserve bone health in women with POI.

Beneficial role of microRNA-328-3p in fracture healing by enhancing osteoblastic viability through the PTEN/PI3K/AKT pathway

Although fragility fracture is a global public health burden, the mechanisms underlying fracture healing remain unclear. The present study aimed to assess the dynamic expression pattern of microRNA-328-3p (miR-328-3p) during fracture healing in patients with fragility fracture and to explore the functional role and mechanisms of miR-328-3p in the regulation of osteoblastic viability. The expression levels of miR-328-3p was examined using reverse transcription-quantitative PCR (RT-qPCR). Osteoblastic proliferation and apoptosis were analyzed via MTT and flow cytometry assays. A luciferase reporter assay was adopted to confirm the interaction between miR-328-3p and its target gene PTEN, and western blotting was used to explore the activity of PI3K/AKT signaling. The results of the present study demonstrated that serum miR-328-3p expression did not significantly differ at the early stage of healing in patients with fracture, but was markedly decreased 14 and 21 days post fixation (P<0.01). PTEN was demonstrated to be a target gene of miR-328-3p and was inhibited by miR-328-3p overexpression in osteoblasts (P<0.001). miR-328-3p overexpression increased osteoblastic proliferation but decreased apoptotic rate, with these effects being reversed by PTEN overexpression (P<0.05). The expression of phosphorylated-AKT was elevated in osteoblasts by miR-328-3p overexpression, but this effect was abolished by overexpressing PTEN. Thus, the present study revealed that miR-328-3p may accelerate fracture healing by promoting osteoblastic viability through the PTEN/PI3K/AKT pathway.

Monitoring and maintaining bone health in patients with Turner syndrome

INTRODUCTION

Subjects affected with Turner Syndrome (TS) suffer low bone mineral density and high risk of fracture from a young age. Estrogen deficiency is considered the main risk factor but other factors, such as intrinsic bone abnormalities, enhanced osteoclastogenesis, vitamin D deficiency and other comorbidities may contribute to the exalted bone fragility.

AREAS COVERED

The authors performed a literature search in PubMed and EMBASE, using selected key words. They focused their search on pathogenetic mechanisms of osteoporosis in TS and updated the diagnosis, prevention and therapeutic interventions.

EXPERT OPINION

Bone health is a concern in subjects with TS, and strategies to prevent osteoporosis and fractures should be considered from childhood. Advice on how to live a healthy lifestyle, including physical activity and correct nutrition, should be given during childhood in order to prevent bone impairment later in life. The screening for vitamin D deficiency should be performed between the ages of 9 and 11, and every 2-3 years thereafter. Early initiation of estrogen replacement therapy (ERT) between 11-12 years of age, prompt titration to the adult dose after 2 years, and long-term follow-up to guarantee compliance with ERT, are the key points of osteoporosis prevention in women with TS.

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.

Turner syndrome and osteoporosis

Turner syndrome is one of the most common sex chromosomal anomalies, characterized by the complete or partial loss of one X chromosome. Females with Turner syndrome are characterized by skeletal abnormalities, short stature and primary ovarian insufficiency. The aim of this narrative review was to identify the underlying mechanisms of osteoporosis in Turner syndrome, summarize its clinical manifestations and provide suggestions regarding the management of osteoporosis. Girls and women with Turner syndrome have lower bone mineral density and a higher fracture rate than healthy individuals. The most important risk factors for osteoporosis are inadequately treated primary ovarian insufficiency, followed by intrinsic bone abnormalities. Comorbidities that further increase the risk of osteoporosis include vitamin D deficiency, celiac disease and inflammatory bowel disease. In addition, hearing problems can predispose to falls. Early initiation of hormone replacement therapy (HRT) at the age of 11-13 years, prompt titration to the adult dose after 2 years and long-term follow-up to ensure compliance with HRT are the cornerstones of osteoporosis prevention in women with Turner syndrome.

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.