Growth and growth hormone in Turner syndrome: Looking back, looking ahead

Transition from pediatrics to adult health care in girls with turner syndrome

INTRODUCTION

Turner Syndrome is a rare condition secondary to a complete or partial loss of one X chromosome, leading to a wide spectrum of clinical manifestations. Short stature, gonadal dysgenesis, cardiovascular malformations, and dysmorphic features characterize its common clinical picture.

AREAS COVERED

The main endocrine challenges in adolescent girls with Turner Syndrome are puberty induction (closely intertwined with growth) and fertility preservation. We discuss the most important clinical aspects that should be faced when planning an appropriate and seamless transition for girls with Turner Syndrome.

EXPERT OPINION

Adolescence is a complex time for girls and boys: the passage to young adulthood is characterized by changes in the social, emotional, and educational environment. Adolescence is the ideal time to encourage the development of independent self-care behaviors and to make the growing girl aware of her health, thus promoting healthy lifestyle behaviors. During adulthood, diet and exercise are of utmost importance to manage some of the common complications that can emerge with aging. All clinicians involved in the multidisciplinary team must consider that transition is more than hormone replacement therapy: transition in a modern Healthcare Provider is a proactive process, shared between pediatric and adult endocrinologists.

What Is the Role for Pediatric Endocrinologists in the Management of Skeletal Dysplasias?

Children with skeletal dysplasias have not been consistently managed by pediatric endocrinologists despite the recognized expertise of these practitioners in managing genetic growth disorders. Growth-altering treatments have broadened the role of the pediatric endocrinologist to manage and sometimes become primary coordinators for genetic disorders such as Turner syndrome and Prader-Willi syndrome. We illustrate how recent advances in understanding the pathophysiology of skeletal disorders and the development of targeted treatments provide an opportunity for pediatric endocrinologists to further expand their role in managing certain skeletal dysplasias, including achondroplasia.

The Exon 3-Deleted Growth Hormone Receptor (d3GHR) Polymorphism-A Favorable Backdoor Mechanism for the GHR Function

Growth hormone (GH) is a peptide hormone that plays a crucial role in controlling growth, development, and lifespan. Molecular regulation of GH is accomplished via the GH receptor (GHR), which is the main factor influencing human development and is essential to optimal functioning of the GH/IGF-I axis. Two GHR isoforms have been studied, according to the presence (flGHR) or absence (d3GHR) of exon 3. The d3GHR isoform, which lacks exon 3 has recently been related to longevity; individuals carrying this isoform have higher receptor activity, improved signal transduction, and alterations in the treatment response and efficacy compared with those carrying the wild type (WT) isoform (flGHR). Further, studies performed in patients with acromegaly, Prader-Willi syndrome, Turner syndrome, small for gestational age (SGA), and growth hormone deficiency (GHD) suggested that the d3GHR isoform may have an impact on the relationship between GH and IGF-I levels, height, weight, BMI, and other variables. Other research, however, revealed inconsistent results, which might have been caused by confounding factors, including limited sample sizes and different experimental methods. In this review, we lay out the complexity of the GHR isoforms and provide an overview of the major pharmacogenetic research conducted on this ongoing and unresolved subject.

Individuals with numerical and structural variations of sex chromosomes: interdisciplinary management with focus on fertility potential

Diagnosis and management of individuals who have differences of sex development (DSD) due to numerical or structural variations of sex chromosomes (NSVSC) remains challenging. Girls who have Turner syndrome (45X) may present with varying phenotypic features, from classical/severe to minor, and some remain undiagnosed. Boys and girls who have 45,X/46,XY chromosomal mosaicism may have Turner syndrome-like features and short stature; therefore, unexplained short stature during childhood requires karyotype analysis in both sexes, particularly if characteristic features or atypical genitalia are present. Many individuals with Klinefelter syndrome (47XXY) remain undiagnosed or are only diagnosed as adults due to fertility problems. Newborn screening by heel prick tests could potentially identify sex chromosome variations but would have ethical and financial implications, and in-depth cost-benefit analyses are needed before nationwide screening can be introduced. Most individuals who have NSVSC have lifelong co-morbidities and healthcare should be holistic, personalized and centralized, with a focus on information, psychosocial support and shared decision-making. Fertility potential should be assessed individually and discussed at an appropriate age. Oocyte or ovarian tissue cryopreservation is possible in some women who have Turner syndrome and live births have been reported following assisted reproductive technology (ART). Testicular sperm cell extraction (TESE) is possible in some men who have 45,X/46,XY mosaicism, but there is no established protocol and no reported fathering of children. Some men with Klinefelter syndrome can now father a child following TESE and ART, with multiple reports of healthy live births. Children who have NSVSC, their parents and DSD team members need to address possibilities and ethical questions relating to potential fertility preservation, with guidelines and international studies still needed.

Turner Syndrome

Turner syndrome (TS) affects approximately 1 out of every 1500–2500 live female births, with clinical features including short stature, premature ovarian failure, dysmorphic features and other endocrine, skeletal, cardiovascular, renal, gastrointestinal and neurodevelopmental organ system involvement. TS, a common genetic syndrome, is caused by sex chromosome aneuploidy, mosaicism or abnormalities with complete or partial loss of function of the second X chromosome. Advances in genetic and genomic testing have further elucidated other possible mechanisms that contribute to pathogenic variability in phenotypic expression that are not necessarily explained by monosomy or haploinsufficiency of the X chromosome alone. The role of epigenetics in variations of gene expression and how this knowledge can contribute to more individualized therapy is currently being explored. TS is established as a multisystemic condition, with several endocrine manifestations of TS affecting growth, puberty and fertility having significant impact on quality of life. Treatment guidelines are in place for the management of these conditions; however, further data on optimal management is needed.

Adult Height in 299 Patients with Turner Syndrome with or without Growth Hormone Therapy: Results and Literature Review

CONTEXT

Treatment with growth hormone (GH) is considered effective in improving adult height (AH) in Turner syndrome (TS). However, there are few studies comparing AH between treated patients and a concurrent untreated group.

OBJECTIVE

To assess the efficacy of GH treatment in improving AH in TS and to review previous published studies with treated and untreated groups.

PARTICIPANTS AND METHODS

We retrospectively analyzed clinical data and AH of a large cohort of GH-treated (n = 168) and untreated (n = 131) patients with TS. Data are shown as median and interquartile range (IQR). We assessed pretreatment variables related with AH and compared our results with 16 studies that also included an untreated group.

RESULTS

The GH-treated group was 6.2 cm taller than the untreated group (AH = 149 cm [IQR 144.5-152.5 cm] vs. 142.8 cm [IQR 139-148 cm], p < 0.001) after 4.9 years of GH treatment with a dose of 0.35 mg/kg/week. AH SDS corrected for target height (TH) was 7.2 cm higher in GH-treated patients. AH SDS ≥-2 was more frequent in GH-treated patients (43%) than in untreated patients (16%, p < 0.001). AH SDS was also more frequently within the TH range in the GH-treated group (52%) than in the untreated group (15%, p < 0.001). Height SDS at start of GH therapy and TH SDS were positively correlated with AH (p < 0.001; R2 = 0.375). Considering the current result together with previous similar publications, a mean AH gain of 5.7 cm was observed in GH-treated (n = 696) versus untreated (n = 633) patients.

CONCLUSIONS

Our study strengthens the evidence for efficacy of GH therapy in patients with TS from different populations.

Main Physical Features, Echocardiographic and Renal Ultrasonographic Findings of Turner Syndrome in 107 Pediatric Patients

Turner syndrome (TS) is one of the most common malformation syndromes in females. A total number of 107 TS patients, diagnosed between 2000 and 2018, were evaluated for their phenotypic features, and cardiac and renal findings. The mean age of patients at admission was 10.08 ± 4.9 years (range, newborn to 18 years). Four different karyotype groups were encountered, and the most common findings in all groups were short stature, followed by cubitus valgus. Echocardiographic findings of 85 patients were available among which 63 (n = 63/85, 74.1%) were found to be normal. The most common cardiac anomaly was left ventricular outflow tract/aortic arch pathology detected in 9 patients (n = 9/22, 40.9%). Renal malformations were detected in 15 patients (n = 15/84, 17.9%) by renal ultrasonography, and horseshoe kidney was the most common renal malformation, followed by left multicystic dysplastic kidney. There was no significant difference in the frequency of renal malformation and cardiac anomalies among the 4different karyotype groups (χ² exact test, p > 0.05). Compared with the literature, the frequency of renal anomalies was detected at a lower rate. Karyotype analysis should be carried out in all female patients with short stature, even if there are no associated phenotypic findings suggestive of TS. Since cardiac anomalies are frequently seen in TS patients and they represent a common cause of mortality, echocardiography should be carried out as soon as the definite diagnosis is established. Renal anomalies may be less frequent than cardiac anomalies; however, evaluation of TS patients with renal ultrasonography should be done at the time of diagnosis. Although renal ultrasonography can be used as the initial renal screening in TS patients, it may underestimate the frequency of renal malformation; hence, further management may be required.

Hydrogels For Peptide Hormones Delivery: Therapeutic And Tissue Engineering Applications

Peptides are the most abundant biological compounds in the cells that act as enzymes, hormones, structural element, and antibodies. Mostly, peptides have problems to move across the cells because of their size and poor cellular penetration. Therefore, a carrier that could transfer peptides into cells is ideal and would be effective for disease treatment. Until now, plenty of polymers, e.g., polysaccharides, polypeptides, and lipids were used in drug delivery. Hydrogels made from polysaccharides showed significant development in targeted delivery of peptide hormones because of their natural characteristics such as networks, pore sizes, sustainability, and response to external stimuli. The main aim of the present review was therefore, to gather the important usages of the hydrogels as a carrier in peptide hormone delivery and their application in tissue engineering and regenerative medicine.

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.