SHOX Haploinsufficiency as a Cause of Syndromic and Nonsyndromic Short Stature

Patient and Caregiver Impressions of the Impact of Madelung Deformity: A CoULD Registry Analysis

PURPOSE

This study seeks to investigate demographics of patients with Madelung deformity in a large, geographically diverse sample and understand patient and caregiver perceptions of the impact of this condition. We hypothesized that patients with untreated Madelung deformity have greater pain and lower function compared to the normal population but are less affected than the chosen control group, namely, patients with proximal radioulnar synostosis (PRUS).

METHODS

This retrospective study queried the Congenital Upper Limb Differences (CoULD) Registry, a multicenter registry of patients treated in tertiary care pediatric hospitals. We searched patients enrolled as of July 2022 and identified 3,980 total patients and 66 (1.7%) with a diagnosis of Madelung deformity. We reviewed demographics and Patient-Reported Outcomes Measurement Information System (PROMIS; peer relations, depressive symptoms, pain interference, and upper extremity function domains) scores at time of enrollment. We used a matched cohort comparison with propensity scoring for 50 patients with Madelung deformity and 50 patients with PRUS (control cohort).

RESULTS

Patients with Madelung deformity presented at an average age of 13.1 years (± 2.1 years). Ninety-eight percent were female, and 82% were White. Seventy-four percent had distal radius-only deformity. Upper extremity PROMIS scores in both the Madelung deformity and the PRUS groups were significantly "worse" than normal, confirming our hypothesis. The Madelung deformity and PRUS cohort scores were not consistently different from one another. PROMIS scores from all other domains, including pain interference, were similar to, or better than normal for both groups, disproving the second part of our hypothesis.

CONCLUSIONS

Patients with Madelung deformity averaged 13 years of age and were nearly all female, and the majority had only distal involvement of the radius. Patients with Madelung deformity had lower function based on PROMIS scores, similar to the control cohort, whereas all other PROMIS measures were similar to or better when compared to normal values. Pain interference scores in both cohorts were lower than normal values. Patients with Madelung deformity have decreased function, similar to the comparative cohort of patients with PRUS, but do not present with increased pain.

TYPE OF STUDY/LEVEL OF EVIDENCE

Symptom Prevalence III.

Prevalence, diagnostic features, and medical outcomes of females with Turner syndrome with a trisomy X cell line (45,X/47,XXX): Results from the InsighTS Registry

Turner syndrome (TS) is defined by partial or complete absence of a sex chromosome. Little is known about the phenotype of individuals with TS mosaic with trisomy X (45,X/47,XXX or 45,X/46,XX/47,XXX) (~3% of TS). We compared the diagnostic, perinatal, medical, and neurodevelopmental comorbidities of mosaic 45,X/47,XXX (n = 35, 9.4%) with nonmosaic 45,X (n = 142) and mosaic 45,X/46,XX (n = 66). Females with 45,X/47,XXX had fewer neonatal concerns and lower prevalence of several TS-related diagnoses compared with 45,X; however the prevalence of neurodevelopmental and psychiatric diagnoses were not different. Compared to females with 45,X/46,XX, the 45,X/47,XXX group was significantly more likely to have structural renal anomalies (18% vs. 3%; p = 0.03). They were twice as likely to have congenital heart disease (32% vs. 15%, p = 0.08) and less likely to experience spontaneous menarche (46% vs. 75% of those over age 10, p = 0.06), although not statistically significant. Congenital anomalies, hypertension, and hearing loss were primarily attributable to a higher proportion of 45,X cells, while preserved ovarian function was most associated with a higher proportion of 46,XX cells. In this large TS cohort, 45,X/47,XXX was more common than previously reported, individuals were phenotypically less affected than those with 45,X, but did have trends for several more TS-related diagnoses than individuals with 45,X/46,XX.

Oral hormone replacement therapy and uterine volume in Korean adolescents with Turner syndrome: A retrospective case-control study

STUDY OBJECTIVE

We aimed to identify critical factors for uterine development by comparing uterine volume (UV) among patients with Turner syndrome (TS) who underwent pubertal induction (PI), patients with TS who had natural menarche (NM), and patients in a non-TS control group.

METHODS

This retrospective case-control study included patients with TS who had undergone PI with oral estrogen in a PI group(n=31) and a NM group(n=7). The control group included patients without TS with spontaneous puberty who underwent pelvic ultrasound at 16 years of age. For TS patients, both the UV from the first ultrasound performed at age 16 or older (1st-UV) and the UV from the most recent final ultrasound (final-UV) were obtained.

RESULTS

The 1st-UV was larger for patients in the NM group than those in the PI group (p<0.001), but did not differ significantly between the NM and control groups (p=0.375). The final-UV of the PI group was larger than their 1st-UV (p<0.001), but still smaller than the NM group (p=0.021). HRT duration and 1st-UV of PI group were positively correlated (p=0.048). There were no variables that were significantly correlated with final-UV of PI group.

CONCLUSION

Patients with TS who experienced NM showed normal uterine development, but TS patients who underwent PI showed significantly smaller, undeveloped UV. While HRT duration and UV are positively correlated at the beginning of HRT, it is unclear what determines the final UV; however, late PI initiation and use of oral estrogen probably contributed to the lack of UV development.

Clinical practice guidelines for the care of girls and women with Turner syndrome

Turner syndrome (TS) affects 50 per 100 000 females. TS affects multiple organs through all stages of life, necessitating multidisciplinary care. This guideline extends previous ones and includes important new advances, within diagnostics and genetics, estrogen treatment, fertility, co-morbidities, and neurocognition and neuropsychology. Exploratory meetings were held in 2021 in Europe and United States culminating with a consensus meeting in Aarhus, Denmark in June 2023. Prior to this, eight groups addressed important areas in TS care: (1) diagnosis and genetics, (2) growth, (3) puberty and estrogen treatment, (4) cardiovascular health, (5) transition, (6) fertility assessment, monitoring, and counselling, (7) health surveillance for comorbidities throughout the lifespan, and (8) neurocognition and its implications for mental health and well-being. Each group produced proposals for the present guidelines, which were meticulously discussed by the entire group. Four pertinent questions were submitted for formal GRADE (Grading of Recommendations, Assessment, Development and Evaluation) evaluation with systematic review of the literature. The guidelines project was initiated by the European Society for Endocrinology and the Pediatric Endocrine Society, in collaboration with members from the European Society for Pediatric Endocrinology, the European Society of Human Reproduction and Embryology, the European Reference Network on Rare Endocrine Conditions, the Society for Endocrinology, and the European Society of Cardiology, Japanese Society for Pediatric Endocrinology, Australia and New Zealand Society for Pediatric Endocrinology and Diabetes, Latin American Society for Pediatric Endocrinology, Arab Society for Pediatric Endocrinology and Diabetes, and the Asia Pacific Pediatric Endocrine Society. Advocacy groups appointed representatives for pre-meeting discussions and the consensus meeting.

Role of genetic investigation in the diagnosis of short stature in a cohort of Italian children

BACKGROUND

Short stature (SS) is defined as height more than 2 standard deviations below the mean for age and sex. Hypothyroidism, celiac disease, growth hormone deficiency, hormonal abnormalities, and genetic conditions are among its causes. A wide range of conditions often due to largely unknown genetic variants can elude conventional diagnostic workup.

AIM

We used next-generation sequencing (NGS) to better understand the etiology of SS in a cohort of Italian children.

PATIENTS AND METHODS

The study sample was 125 children with SS of unknown origin referred to our Institute between 2015 and 2021. All had undergone complete auxological and hormonal investigations to exclude common causes of SS. Genetic analysis was performed using a NGS panel of 104 genes. Clinical data were reviewed to clarify the pathogenicity of the variants detected.

RESULTS

In this cohort, 43 potentially causing variants were identified in 38 children. A syndromic genetic condition was diagnosed in 7: Noonan syndrome in 3, Leri-Weill syndrome in 3, and hypochondroplasia in 1. Moreover, 8 benign variants and other 37 like benign variants were found. In 88 children, 179 variants of uncertain significance (VUS) were identified. No variant was found in 16 children.

CONCLUSION

Genetic analysis is a useful tool in the diagnostic workup of patients with SS, in adapting management and treatment, and in identifying syndromes with mild atypical clinical features. The role of VUS should not be underestimated, particularly when multiple VUS with possible mutual worsening effects are present in the same child.

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.

Influences of sex chromosome aneuploidy on height, weight, and body mass index in human childhood and adolescence

Sex chromosome aneuploidies (SCAs) are collectively common conditions caused by carriage of a sex chromosome dosage other than XX for females and XY for males. Increases in sex chromosome dosage (SCD) have been shown to have an inverted-U association with height, but we lack combined studies of SCA effects on height and weight, and it is not known if any such effects vary with age. Here, we study norm-derived height and weight z-scores in 177 youth spanning 8 SCA karyotypes (XXX, XXY, XYY, XXXX, XXXY, XXYY, XXXXX, and XXXXY). We replicate a previously described inverted-U association between mounting SCD and height, and further show that there is also a muted version of this effect for weight: both phenotypes are elevated until SCD reaches 4 for females and 5 for males but decrease thereafter. We next use 266 longitudinal measures available from a subset of karyotypes (XXX, XXY, XYY, and XXYY) to show that mean height in these SCAs diverges further from norms with increasing age. As weight does not diverge from norms with increasing age, BMI decreases with increasing age. These findings extend our understanding of growth as an important clinical outcome in SCA, and as a key context for known effects of SCA on diverse organ systems that scale with body size.

Genetic analysis, ultrasound phenotype, and pregnancy outcomes of fetuses with Xp22.33 or Yp11.32 microdeletions

OBJECTIVES

The phenotypes of Xp22.33 or Yp11.32 microdeletions comprising the short-stature homeobox (SHOX) gene have been extensively described in adults and children. Herein, the prenatal ultrasound phenotype and pregnancy outcomes of fetuses with Xp22.33/Yp11.32 microdeletions were analyzed to improve our understanding, diagnosis, and monitoring of this genetic condition in the fetal stage.

METHODS

A total of 9,100 pregnant women referred to tertiary units for prenatal diagnosis were evaluated by chromosomal microarray analysis(CMA).

RESULTS

Seven (0.08 %) fetuses had Xp22.33/Yp11.32 microdeletions, ranging from 243 kb to 1.1 Mb, that comprised SHOX. The ultrasonic phenotypes differed among these fetuses, with three fetuses presenting abnormal bone development, one had labial-palatal deformity and strawberry head, two had an abnormal ultrasonic soft marker, and one had no abnormalities. After genetic counseling, only one couple underwent pedigree assessment, which confirmed the paternal origin of the microdeletion. This infant presented delayed speech development, whereas other three infants showed a typical postnatal development. In three cases, the parents chose to terminate the pregnancy.

CONCLUSIONS

The ultrasonic phenotype of fetuses with Xp22.33/Yp11.32 microdeletions resulting in SHOX heterozygosity loss is variable. Prenatal CMA can quickly and effectively diagnose Xp22.33/Yp11.32 microdeletions and SHOX loss, which may help prenatal counseling.

Efficacy and safety of GH treatment in Japanese children with short stature due to SHOX deficiency: a randomized phase 3 study

We conducted a randomized phase 3 study to investigate the efficacy and safety of GH treatment in prepubertal Japanese patients with short stature due to SHOX deficiency. The patients were randomly allocated to the GH-GH group (n = 10), in which the patients were treated with GH (0.35 mg/kg/wk) subcutaneously once daily for 24 mo, or the no-treatment (NT)-GH group (n = 9), in which the patients were untreated for the first 12 mo and then administered the same dosage of GH for the next 12 mo. At month 12, the ∆height standard deviation score (SDS) for chronological age (CA) and serum IGF-1 level were significantly higher in the GH-GH group than those in the NT-GH group. In contrast, bone age (BA) and ΔBA/ΔCA were numerically higher in the GH-GH group but were not statistically significant. At month 24, these parameters were comparable between the two groups. The height velocity was significantly larger in the GH-GH group during the first year and in the NT-GH group during the second year. No serious adverse drug reactions were observed; however, one patient in the GH-GH group exhibited increased insulin resistance at month 24. These results indicated that GH is a promising treatment option for short stature in patients with SHOX deficiency.

Out of the Silence: Insights into How Genes Escape X-Chromosome Inactivation

The silencing of all but one X chromosome in mammalian cells is a remarkable epigenetic process leading to near dosage equivalence in X-linked gene products between the sexes. However, equally remarkable is the ability of a subset of genes to continue to be expressed from the otherwise inactive X chromosome-in some cases constitutively, while other genes are variable between individuals, tissues or cells. In this review we discuss the advantages and disadvantages of the approaches that have been used to identify escapees. The identity of escapees provides important clues to mechanisms underlying escape from XCI, an arena of study now moving from correlation to functional studies. As most escapees show greater expression in females, the not-so-inactive X chromosome is a substantial contributor to sex differences in humans, and we highlight some examples of such impact.

The Use of Fluorescence In situ Hybridisation in the Diagnosis of Hidden Mosaicism in Egyptian Patients with Turner Syndrome

Background

Turner syndrome (TS) is the most common chromosomal abnormality in females. The diagnosis of TS is based on karyotyping of 30 blood lymphocytes. This technique does not rule out tissue mosaicism or low-grade mosaicism in the blood. Because of the associated risk of gonadoblastoma, mosaicism is especially important in case this involves a Y chromosome.

Aims

This study was set to determine the value of additional genetic studies such as fluorescent in situ hybridisation and the inclusion of buccal cells in search for mosaicism in TS patients.

Settings and Design

This cross-sectional, descriptive study was performed in Human Genetics Department, Medical Research Institute, Alexandria University.

Materials and Methods

Fluorescence in situ hybridisation technique was applied to lymphocyte cultures as well as buccal smears using centromeric probes for X and Y chromosomes. Genotype phenotype correlation was also evaluated.

Statistical Analysis Used

Descriptive study where categorical variables were described using number and percentage and continuous variables were described using mean and standard deviation.

Results

Fluorescence in situ hybridisation technique study detected hidden mosaicism in 60% of studied patients; 20% of patients had a cell line containing Y material, while 40% had variable degrees of X, XX mosaicism, and in the remaining 40% no second cell line was detected. Fluorescence in situ hybridisation study helped identify the origin of the marker to be Y in all patients. The introduction of an additional cell line helped in identifying mosaicism in patients with monosomy X. Virilisation signs were only observed among TS patients with Y cell line mosaicism. The clinical manifestations were more severe in patients with monosomy X than other mosaic cases.

Conclusions

Molecular cytogenetic investigation for all suspected cases of TS should be considered for appropriate treatment plan and genetic counselling.

Shortened fetal long bones: A notable intrauterine phenotypic feature in SHOX-associated skeletal dysplasia

OBJECTIVE

To explore the intrauterine phenotypic spectrum of short stature homeobox-containing (SHOX) gene-associated skeletal dysplasia and provide genetic counseling at-risk pregnancies.

METHOD

We analyzed the fetuses with SHOX-microdeletions identified by single nucleotide polymorphism (SNP)-array. The intrauterine phenotypes and outcomes were further elaborated.

RESULTS

Nine fetuses carrying a single SHOX-microdeletion were reported, with deletion sizes ranging from 0.134 to 1.35 Mb. Shortened long bones were observed in all fetuses, varying from -2.0 standard deviation (SD) to -5.3 SD. Moreover, all cases had a femur length/foot ratio less than 0.87 and a femur/abdominal circumference ratio greater than 0.16, suggesting that non-lethal skeletal dysplasia may be involved. Two fetuses showed intrauterine growth restriction, and two had nasal bone hypoplasia. Prenatal ultrasonography did not reveal other obvious anomalies, including the Madelung deformity. Five microdeletions were inherited and one was de novo. Five terminations and four newborns were recorded. Two newborns had normal stature, and two were short-statured (height <3rd percentile), with one having inflexible wrists.

CONCLUSIONS

SHOX haploinsufficiency may manifest with shortened fetal long bones. The combination of history taking, prenatal ultrasonography, and SNP-array can prompt early prenatal diagnosis and timely postnatal treatment of SHOX-associated skeletal dysplasia.

What the pediatric endocrinologist needs to know about skeletal dysplasia, a primer

Children with skeletal dysplasia are frequently referred to pediatric endocrinologists due to short stature. These children may present with disproportionate growth or medical histories that point to a skeletal dysplasia. This primer will discuss when to be concerned about skeletal dysplasia, the initial steps in evaluation for a skeletal dysplasia, and new therapies that are either recently approved or in development.

Pathogenic copy number variations are associated with foetal short femur length in a tertiary referral centre study

Shortened foetal femur length (FL) is a common abnormal phenotype that often causes anxiety in pregnant women, and standard clinical treatments remain unavailable. We investigated the clinical characteristics, genetic aetiology and obstetric pregnancy outcomes of foetuses with short FL and provided a reference for perinatal management of such cases. Chromosomal microarray analysis was used to analyse the copy number variations (CNV) in short FL foetuses. Of the 218 foetuses with short FL, 33 foetuses exhibited abnormal CNVs, including 19 with pathogenic CNVs and 14 with variations of uncertain clinical significance. Of the 19 foetuses with pathogenic CNVs, four had aneuploidy, 14 had deletions/duplications, and one had pathogenic uniparental diploidy. The 7q11.23 microdeletion was detected in three foetuses. The severity of short FL was not associated with the rate of pathogenic CNVs. The duration of short FL for the intrauterine ultrasound phenotype in foetuses carrying a pathogenic CNV was independent of the gestational age. Further, maternal age was not associated with the incidence of foetal pathogenic CNVs. Adverse pregnancy outcomes occurred in 77 cases, including termination of pregnancy in 63 cases, postnatal dwarfed foetuses with intellectual disability in 11 cases, and three deaths within 3 months of birth. Pathogenic CNVs closely related to foetal short FL were identified, among which the 7q11.23 microdeletion was highly associated with short FL development. This study provides a reference for the perinatal management of foetuses with short FL.

Copy Number Variation and Structural Genomic Findings in 116 Cases of Sudden Unexplained Death between 1 and 28 Months of Age

In sudden unexplained death in pediatrics (SUDP) the cause of death is unknown despite an autopsy and investigation. The role of copy number variations (CNVs) in SUDP has not been well-studied. Chromosomal microarray (CMA) data are generated for 116 SUDP cases with age at death between 1 and 28 months. CNVs are classified using the American College of Medical Genetics and Genomics guidelines and CNVs in our cohort are compared to an autism spectrum disorder (ASD) cohort, and to a control cohort. Pathogenic CNVs are identified in 5 of 116 cases (4.3%). Variants of uncertain significance (VUS) favoring pathogenic CNVs are identified in 9 cases (7.8%). Several CNVs are associated with neurodevelopmental phenotypes including seizures, ASD, developmental delay, and schizophrenia. The structural variant 47,XXY is identified in two cases (2/69 boys, 2.9%) not previously diagnosed with Klinefelter syndrome. Pathogenicity scores for deletions are significantly elevated in the SUDP cohort versus controls (p = 0.007) and are not significantly different from the ASD cohort. The finding of pathogenic or VUS favoring pathogenic CNVs, or structural variants, in 12.1% of cases, combined with the observation of higher pathogenicity scores for deletions in SUDP versus controls, suggests that CMA should be included in the genetic evaluation of SUDP.

The human inactive X chromosome modulates expression of the active X chromosome

The "inactive" X chromosome (Xi) has been assumed to have little impact, in trans, on the "active" X (Xa). To test this, we quantified Xi and Xa gene expression in individuals with one Xa and zero to three Xis. Our linear modeling revealed modular Xi and Xa transcriptomes and significant Xi-driven expression changes for 38% (162/423) of expressed X chromosome genes. By integrating allele-specific analyses, we found that modulation of Xa transcript levels by Xi contributes to many of these Xi-driven changes (≥121 genes). By incorporating metrics of evolutionary constraint, we identified 10 X chromosome genes most likely to drive sex differences in common disease and sex chromosome aneuploidy syndromes. We conclude that human X chromosomes are regulated both in cis, through Xi-wide transcriptional attenuation, and in trans, through positive or negative modulation of individual Xa genes by Xi. The sum of these cis and trans effects differs widely among genes.

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.

Genetic Analysis and Sonography Characteristics in Fetus with SHOX Haploinsufficiency

OBJECTIVE

SHOX haploinsufficiency have been commonly found in isolated short stature (ISS) and Léri-Weill dyschondrosteosis (LWD) patients. However, few publications have described the genetic analysis and clinical characteristics of fetuses with SHOX haploinsufficiency.

METHODS

Chromosomal microarray (CMA) were applied in 14,051 fetuses and sequentially whole exome sequence (WES) in 1340 fetuses who underwent prenatal diagnosis during 2016-2021. The analysis and summary of molecular genetics, sonographic characteristics, and follow-up results were performed in fetuses with SHOX haploinsufficiency without other genetic etiologies. A comparison was made between three groups according to prenatal diagnostic indications.

RESULTS

8 (0.06%) fetuses of SHOX haploinsufficiency were all detected by CMA, of which 5 (62.5%) were detected with short long bones by ultrasound scan, and 4 were inherited from their previously undiagnosed parents. No pathogenic SHOX variants were found by WES. The detection rate of SHOX haploinsufficiency was obviously higher in the short long bone group (2.6%, 5/191) than the other abnormality group (0.03%, 1/3919) or no ultrasound abnormality group (0.02%, 2/9941). Three of the fetuses were liveborn with normal growth up to the age of four and four were terminated.

CONCLUSION

The phenotype of fetuses with SHOX haploinsufficiency is highly varied. Over 1/3 of the cases exhibited no phenotype and nearly 2/3 with short long bones, in the absence of Madelung deformity during fetal development. SHOX haploinsufficiency should be considered in all antenatal presentations, especially in the case of isolated short long bones. CMA can provide effective detection.

SHOX Deletion and Idiopathic Short Stature: What Does the Clinician Need to Know? Case Series Report

Children diagnosticated with idiopathic short stature (ISS) are probably, in most cases, underdiagnosticated. The genetic causes of ISS may be mutations of genes involved in local regulation of the growth plate or genes involved in the GH-IGF1 axis physiology. We present a kindred of five children evaluated for short stature or low normal stature, initially diagnosticated as idiopathic short stature, familial short stature, or being small for gestational age. Clinical signs suggestive of SHOX deletion screening in a child with short stature are low arm span/height ratio, increased sitting height/height ratio, BMI > 50% percentile, Madelung deformity, cubitus valgus, bowing and shortening of the forearm, dislocation of the ulna (at the elbow), and the appearance of muscular hypertrophy. Radiological characteristics suggestive of SHOX deficiency are triangularisation of the distal radial epiphysis, an enlarged diaphysis of the radius plus bowing of the radius, the convexity of the distal radial metaphysis, short fourth and fifth metacarpals, pyramidalization of the carpal row. Treatment with rGH is approved for children with SHOX gene deficiency and short stature. This kindred is an example that familial short stature, idiopathic short stature, and short stature due to a small gestational age are not final diagnoses. Complex investigations are necessary to identify the precise cause, leading to optimal clinical management. Treatment with rGH is an option for some of them; for others, it has no therapeutic response and, in some cases, is even harmful.

Clinical Indications for Growth Hormone Therapy

Growth hormone (GH) is an injectable medication originally used to replace the deficiency of the hormone, but has expanded to treating conditions that may reduce growth and adult height even when the body maintains endogenous GH production. In the United States, there are 8 Food and Drug Administration (FDA)-approved indications for pediatric GH therapy: GH deficiency, Prader-Willi Syndrome, small for gestational age (SGA) without catch-up growth, idiopathic short stature, Turner syndrome, SHOX gene haploinsufficiency, Noonan Syndrome, and chronic renal insufficiency. We characterize the growth patterns and effects of GH treatment in each of these indications. We also review patterns of growth that warrant referral to a pediatric endocrinologist, as well as safety updates. This review is intended to guide practitioners on the initial evaluation and management of patients with short stature, and the indications for GH therapy.

Novel insights in Turner syndrome

PURPOSE OF REVIEW

Turner syndrome is the most common sex chromosome abnormality in female individuals, affecting 1/2000-1/2500 female newborns. Despite the high incidence of this condition, the mechanisms underlying the development of multiorgan dysfunction have not been elucidated.

RECENT FINDINGS

Clinical features involve multiple organ systems and include short stature, dysmorphic facial features, delayed puberty and gonadal failure, cardiac and renal abnormalities, audiologic abnormalities, and a high prevalence of endocrine and autoimmune disorders. Paucity of available genotype/phenotype correlation limits the ability of clinicians to provide accurate guidance and management. Given the advent of robust genetic testing and analysis platforms, developments in the genetic basis of disease are materializing at a rapid pace.

SUMMARY

The objective of this review is to highlight the recent advances in knowledge and to provide a framework with which to apply new data to the foundational understanding of the condition.

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.

The individual and global impact of copy-number variants on complex human traits

The impact of copy-number variations (CNVs) on complex human traits remains understudied. We called CNVs in 331,522 UK Biobank participants and performed genome-wide association studies (GWASs) between the copy number of CNV-proxy probes and 57 continuous traits, revealing 131 signals spanning 47 phenotypes. Our analysis recapitulated well-known associations (e.g., 1q21 and height), revealed the pleiotropy of recurrent CNVs (e.g., 26 and 16 traits for 16p11.2-BP4-BP5 and 22q11.21, respectively), and suggested gene functionalities (e.g., MARF1 in female reproduction). Forty-eight CNV signals (38%) overlapped with single-nucleotide polymorphism (SNP)-GWASs signals for the same trait. For instance, deletion of PDZK1, which encodes a urate transporter scaffold protein, decreased serum urate levels, while deletion of RHD, which encodes the Rhesus blood group D antigen, associated with hematological traits. Other signals overlapped Mendelian disorder regions, suggesting variable expressivity and broad impact of these loci, as illustrated by signals mapping to Rotor syndrome (SLCO1B1/3), renal cysts and diabetes syndrome (HNF1B), or Charcot-Marie-Tooth (PMP22) loci. Total CNV burden negatively impacted 35 traits, leading to increased adiposity, liver/kidney damage, and decreased intelligence and physical capacity. Thirty traits remained burden associated after correcting for CNV-GWAS signals, pointing to a polygenic CNV architecture. The burden negatively correlated with socio-economic indicators, parental lifespan, and age (survivorship proxy), suggesting a contribution to decreased longevity. Together, our results showcase how studying CNVs can expand biological insights, emphasizing the critical role of this mutational class in shaping human traits and arguing in favor of a continuum between Mendelian and complex diseases.

SHOX far-downstream deletion in a patient with nonsyndromic short stature

Haploinsufficiency of SHOX represents one of the major genetic causes of nonsyndromic short stature. To date, eight DNA elements around SHOX exons have been proposed as putative enhancer regions. Although six copy-number variations (CNVs) downstream to the known enhancer regions have recently been identified in patients with short stature, the pathogenicity of these CNVs remains uncertain. Here, we identified a paternally derived SHOX far-downstream deletion in a boy. The deletion involved a ~100 kb genomic interval at a position >60 kb away from the known enhancer regions. The boy exhibited moderate short stature with nonspecific skeletal changes. The height of the father was within the normal range but lower than the mid-parental height. The deletion of the boy and the six previously reported CNVs mostly overlapped; however, all CNVs had unique breakpoints. The deletion of our case encompassed a ~30 kb genomic interval that has previously been associated with a 4C-seq peak, as well as several SHOX-regulatory SNPs/indels. These results indicate that the SHOX far-downstream region contains a novel cis-acting enhancer, whose deletion leads to nonsyndromic short stature of various degree. In addition, our data highlight genomic instability of SHOX-flanking regions that underlies diverse nonrecurrent CNVs.

Novel Insights Into the Genetic Causes of Short Stature in Children

Short stature is a common reason for consulting a growth specialist during childhood. Normal height is a polygenic trait involving a complex interaction between hormonal, nutritional and psychosocial components. Genetic factors are becoming very important in the understanding of short stature. After exclusion of the most frequent causes of growth failure, clinicians need to evaluate whether a genetic cause might be taken into consideration. In fact, genetic causes of short stature are probably misdiagnosed during clinical practice and the underlying cause of short stature frequently remains unknown, thus classifying children as having idiopathic short stature (ISS). However, over the past decade, novel genetic techniques have led to the discovery of novel genes associated with linear growth and thus to the ability to define new possible aetiologies of short stature. In fact, thanks to the newer genetic advances, it is possible to properly re-classify about 25–40% of children previously diagnosed with ISS. The purpose of this article is to describe the main monogenic causes of short stature, which, thanks to advances in molecular genetics, are assuming an increasingly important role in the clinical approach to short children.

Balanced assessment of growth disorders using clinical, endocrinological, and genetic approaches

Determining the pathogenesis of pediatric growth disorders is often challenging. In many cases, no pathogenesis is identified, and a designation of idiopathic short stature is used. The investigation of short stature requires a combination of clinical, endocrinological, and genetic evaluation. The techniques used are described, with equal importance being given to each of the 3 approaches. Clinical skills are essential to elicit an accurate history, family pedigree, and symptoms of body system dysfunction. Endocrine assessment requires hormonal determination for the diagnosis of hormone deficiency and initiation of successful replacement therapy. Genetic analysis has added a new dimension to the investigation of short stature and now uses next-generation sequencing with a candidate gene approach to confirm probable recognizable monogenic disorders and exome sequencing for complex phenotypes of unknown origin. Using the 3 approaches of clinical, endocrine, and genetic probes with equal status in the hierarchy of investigational variables provides the clinician with the highest chance of identifying the correct causative pathogenetic mechanism in a child presenting with short stature of unknown origin.

Detection of Del/Dup Inside SHOX/PAR1 Region in Children and Young Adults with Idiopathic Short Stature

Short stature is a common growth disorder defined as a body height two standard deviations (SD) or more below the mean for a given age, gender, and population. A large part of the cases remains unexplained and is referred to as having idiopathic short stature (ISS). One of the leading genetic causes of short stature is variants of short stature homeobox-containing gene (SHOX) and is considered to be responsible for 2–15% of ISS. We aimed to analyse the regulatory and coding region of SHOX in Slovenian children and young adults with ISS and to investigate the pathogenicity of detected variants. Our cohort included 75 children and young adults with ISS. Multiplex ligation-dependent probe amplification (MLPA) was performed in all participants for the detection of larger copy number variations (CNVs). Sanger sequencing was undertaken for the detection of point variants, small deletions, and insertions. A total of one deletion and two duplications were discovered using the MLPA technique. Only one of these four variants was identified as disease-causing and occurred in one individual, which represents 1.3% of the cohort. With Sanger sequencing, two variants were discovered, but none of them appeared to have a pathogenic effect on height. According to the results, in the Slovenian population of children and young adults with ISS, SHOX deficiency is less frequent than expected considering existing data from other populations.

Retrospective Diagnosis of a Novel ACAN Pathogenic Variant in a Family With Short Stature: A Case Report and Review of the Literature

Short stature is a frequent disorder in the pediatric population and can be caused by multiple factors. In the last few years, the introduction of Next Generation Sequencing (NGS) in the molecular diagnostic workflow led to the discovery of mutations in novel genes causing short stature including heterozygous mutations in ACAN gene. It encodes for aggrecan, a primary proteoglycan component specific for the structure of the cartilage growth plate, articular and intervertebral disc. We report a novel ACAN heterozygous pathogenic variant in a family with idiopathic short stature, early-onset osteoarthritis and osteoarthritis dissecans (SSOAOD). We also performed a literature review summarizing the clinical characteristic of ACAN's patients. The probands are two Caucasian sisters with a family history of short stature and osteoarthritis dissecans. They showed dysmorphic features such as mild midface hypoplasia, brachydactyly and broad thumbs, especially the great toes. The same phenotype was presented in the mother who had had short stature and suffered from intervertebral disc disease. DNA sequencing identified a heterozygous pathogenic variation (c.4390delG p.Val1464Ter) in the sisters, with a maternal inheritance. The nonsense mutation, located on exon 12, results in premature truncation and presumed loss of protein function. In terms of treatment, our patients underwent recombinant human growth hormone replacement therapy, associated with gonadotropin releasing hormone therapy, in order to block early growth cessation and therefore reach a better final height. Our case suggests that SSOAOD ACAN related should be considered in the differential diagnosis of children with autosomal dominant short stature and family history of joints disease.

Transcription factors in neurodevelopmental and associated psychiatric disorders: A potential convergence for genetic and environmental risk factors

Neurodevelopmental disorders (NDDs) are a heterogeneous and highly prevalent group of psychiatric conditions marked by impairments in the nervous system. Their onset occurs during gestation, and the alterations are observed throughout the postnatal life. Although many genetic and environmental risk factors have been described in this context, the interactions between them challenge the understanding of the pathways associated with NDDs. Transcription factors (TFs)-a group of over 1,600 proteins that can interact with DNA, regulating gene expression through modulation of RNA synthesis-represent a point of convergence for different risk factors. In addition, TFs organize critical processes like angiogenesis, blood-brain barrier formation, myelination, neuronal migration, immune activation, and many others in a time and location-dependent way. In this review, we summarize important TF alterations in NDD and associated disorders, along with specific impairments observed in animal models, and, finally, establish hypotheses to explain how these proteins may be critical mediators in the context of genome-environment interactions.

A High Proportion of Novel ACAN Mutations and Their Prevalence in a Large Cohort of Chinese Short Stature Children

CONTEXT

Aggrecan, encoded by the ACAN gene, is the main proteoglycan component in the extracellular cartilage matrix. Heterozygous mutations in ACAN have been reported to cause idiopathic short stature. However, the prevalence of ACAN pathogenic variants in Chinese short stature patients and clinical phenotypes remain to be evaluated.

OBJECTIVE

We sought to determine the prevalence of ACAN pathogenic variants among Chinese short stature children and characterize the phenotypic spectrum and their responses to growth hormone therapies.

PATIENTS AND METHODS

Over 1000 unrelated short stature patients ascertained across China were genetically evaluated by next-generation sequencing-based test.

RESULT

We identified 10 novel likely pathogenic variants and 2 recurrent pathogenic variants in this cohort. None of ACAN mutation carriers exhibited significant dysmorphic features or skeletal abnormities. The prevalence of ACAN defect is estimated to be 1.2% in the whole cohort; it increased to 14.3% among those with advanced bone age and to 35.7% among those with both advanced bone age and family history of short stature. Nonetheless, 5 of 11 ACAN mutation carries had no advanced bone age. Two individuals received growth hormone therapy with variable levels of height SD score improvement.

CONCLUSION

Our data suggest that ACAN mutation is 1 of the common causes of Chinese pediatric short stature. Although it has a higher detection rate among short stature patients with advanced bone age and family history, part of affected probands presented with delayed bone age in Chinese short stature population. The growth hormone treatment was moderately effective for both individuals.

Pubertal boy presenting with mild disproportionate short stature

A boy aged 12 years was referred with short stature. He was born at term, of adequate weight (10-25th centile) and length (10-25th centile), which settled to just below the third centile from 18 months of age, with a growth deceleration in the last 6 months (growth velocity -2.1 standard deviation score, according to Tanner charts). He was otherwise asymptomatic. His mother's height was 155 cm, and father's height 158 cm, and he was growing near his target height centile (-2.26 SDS, <3rd centile).On examination, his height was -2.22 SDS, with normal weight and body mass index (BMI). Pubertal stage corresponded to Tanner 2, with a testicular volume of 4 mL. His legs and forearms appeared shorter, with arm span/height ratio 0.93 (normal value >0.965) and sitting height/height ratio 0.56 (slightly above the normal upper value of 0.55). He resembled his father, whose wrists were abnormally curved (figure 1). The patient's hand X-ray showed that bone age was similar to chronological age.

White-Sutton syndrome with hot water epilepsy and coexistence of SHOX gene variations

The purpose of this study is to reveal the effect on the clinical phenotype of variants detected at family examination of a case of combined pogo transposable element derived with zinc finger domain (POGZ) gene, tubulin folding cofactor E (TBCE) gene, and short stature homeobox (SHOX) gene variation. A Turkish non-consanguineous family consisting of five members was investigated. Whole exome sequence analysis and chromosomal microarray analysis (CMA) were performed for a 2-year-old male patient (the proband) with global developmental delay, hypotonia, dysmorphia, and hot water epilepsy. Targeted sequence and chromosomal microarray analyses were performed for each family member. A heterozygous c.3908_3911delTCTG/p.V1303fs*6 variant was detected in the POGZ gene and a heterozygous c.626 T > G(p.L209X) variant in the TBCE gene in the proband. In addition, a gain of 0.1 MB was detected in the Xp22.33(602488-733497) × 3/Yp11.32(552488-683497) × 3 region at CMA. The SHOX (312865) gene defined in Online Mendelian Inheritance in Man is located in this region. While the proband's father and brother had heterozygous variations only in the TBCE gene, neither TBCE nor POGZ mutations were detected in the mother or sister. A gain in Xp22.33(419224-883640) × 3 was detected in the mother at CMA. Except for short stature and Madelung deformity, no phenotypical findings were detected in the mother. Other family members were also phenotypically normal. The family screening confirmed that dysmorphic findings and global developmental delay in the proband resulted from the variation in the POGZ gene, while short stature was caused by the gain in the Xp22.33(602488-733497) × 3/Yp11.32(552488-683497) × 3 region. In addition, the pathogenic POGZ gene variation in our patient may be a possible cause of hot water epilepsy. Heterozygous variation in the TBCE gene was clinically insignificant. Hot water epilepsy has not previously been reported in the rare patients with POGZ gene mutation. Additionally, in contrast to the previous literature, the proband exhibited no features of autism. It should also be remembered that posterior fossa abnormalities are frequently seen in these patients. We think that this case and family review involving POGZ and SHOX gene mutations will make a useful contribution to the existing literature.

Identification and Tissue-Specific Characterization of Novel SHOX-Regulated Genes in Zebrafish Highlights SOX Family Members Among Other Genes

SHOX deficiency causes a spectrum of clinical phenotypes related to skeletal dysplasia and short stature, including Léri-Weill dyschondrosteosis, Langer mesomelic dysplasia, Turner syndrome, and idiopathic short stature. SHOX controls chondrocyte proliferation and differentiation, bone maturation, and cellular growth arrest and apoptosis via transcriptional regulation of its direct target genes NPPB, FGFR3, and CTGF. However, our understanding of SHOX-related pathways is still incomplete. To elucidate the underlying molecular mechanisms and to better understand the broad phenotypic spectrum of SHOX deficiency, we aimed to identify novel SHOX targets. We analyzed differentially expressed genes in SHOX-overexpressing human fibroblasts (NHDF), and confirmed the known SHOX target genes NPPB and FGFR among the most strongly regulated genes, together with 143 novel candidates. Altogether, 23 genes were selected for further validation, first by whole-body characterization in developing shox-deficient zebrafish embryos, followed by tissue-specific expression analysis in three shox-expressing zebrafish tissues: head (including brain, pharyngeal arches, eye, and olfactory epithelium), heart, and pectoral fins. Most genes were physiologically relevant in the pectoral fins, while only few genes were also significantly regulated in head and heart tissue. Interestingly, multiple sox family members (sox5, sox6, sox8, and sox18) were significantly dysregulated in shox-deficient pectoral fins together with other genes (nppa, nppc, cdkn1a, cdkn1ca, cyp26b1, and cy26c1), highlighting an important role for these genes in shox-related growth disorders. Network-based analysis integrating data from the Ingenuity pathways revealed that most of these genes act in a common network. Our results provide novel insights into the genetic pathways and molecular events leading to the clinical manifestation of SHOX deficiency.

Growth failure: 'idiopathic' only after a detailed diagnostic evaluation

The terms 'idiopathic short stature' (ISS) and 'small for gestational age' (SGA) were first used in the 1970s and 1980s. ISS described non-syndromic short children with undefined aetiology who did not have growth hormone (GH) deficiency, chromosomal defects, chronic illness, dysmorphic features or low birth weight. Despite originating in the pre-molecular era, ISS is still used as a diagnostic label today. The term 'SGA' was adopted by paediatric endocrinologists to describe children born with low birth weight and/or length, some of whom may experience lack of catch-up growth and present with short stature. GH treatment was approved by the FDA for short children born SGA in 2001, and by the EMA in 2003, and for the treatment of ISS in the US, but not Europe, in 2003. These approvals strengthened the terms 'SGA' and 'ISS' as clinical entities. While clinical and hormonal diagnostic techniques remain important, it is the emergence of genetic investigations that have led to numerous molecular discoveries in both ISS and SGA subjects. The primary message of this article is that the labels ISS and SGA are not definitive diagnoses. We propose that the three disciplines of clinical evaluation, hormonal investigation and genetic sequencing should have equal status in the hierarchy of short stature assessments and should complement each other to identify the true pathogenesis in poorly growing patients.

Impact of growth hormone treatment on scoliosis development and progression: analysis of 1128 patients with idiopathic short stature

OBJECTIVES

The purpose of this study was to evaluate the impact of recombinant human growth hormone (rhGH) on the development and progression of scoliosis in patients with idiopathic short stature (ISS).

METHODS

Patients with ISS who underwent rhGH treatment from 1997 to 2017 and were followed up for scoliosis screening with serial radiographic examination were included. For assessing scoliosis development, patients who did not have scoliosis at the time of rhGH treatment were included and followed up to determine whether de novo scoliosis developed during the treatment. For evaluating scoliosis progression, patients who already had scoliosis were analyzed. Univariate and multivariate Cox regression analyses of demographic and radiographic variables were performed to determine the related factors in the development and progression of scoliosis.

RESULTS

For assessing scoliosis development, 1093 patients were included. The average duration of rhGH treatment was about 2 years. De novo scoliosis developed in 32 patients (3.7%). The analysis revealed that sex (p=0.016) and chronological age (p=0.048) were statistically significant factors associated with scoliosis development. However, no relationship was observed between scoliosis development and rhGH treatment types or duration. Among 67 patients who already had scoliosis at the time of rhGH treatment, 11 (16.4%) showed scoliosis progression. However, the rhGH types and duration also did not affect scoliosis progression.

CONCLUSIONS

De novo scoliosis developed in 3.7% and scoliosis progressed in 16.4% of the patients during rhGH treatment. However, scoliosis development or progression was not affected by the types or duration of rhGH treatment in patients with ISS.

Screening of the SHOX/PAR1 region using MLPA and miRNA expression profiling in a group of Egyptian children with non-syndromic short stature

Background

Short stature is defined as a body height below the third percentile, based on chronological age, or 2 standard deviations (SD) below the national height standard. The prevalence of short stature is around 2% of children worldwide. Several gene deficiencies have been associated with the etiology of short stature. The SHOX is an important candidate gene for short stature, as its haploinsufficiency underlies syndromic and non-syndromic short stature. Partial and complete duplications of SHOX have been reported in patients with short stature. Proper genetic diagnosis of these children allows for appropriate therapeutic approaches to be administered. Since copy number variation (CNV) is a possible mechanism of interhuman variability and pathogenic disease, the multiplex ligation-dependent probe amplification technique (MLPA) can be used as an initial screening technique. Cartilage tissue expresses specific microRNAs (miRNAs), which play an essential role in the regulation of chondrocyte proliferation and differentiation during growth plate development. We aimed to assess the SHOX/PAR1 region using CNV profiling for non-syndromic short stature in Egyptian children with and without growth hormone deficiency using the MLPA technique and expression profiling of miR-1, miR-15a, and miR-140 using quantitative real-time polymerase chain reaction (qRT-PCR) in a group of Egyptian children with non-syndromic short stature.

Results

Of the fifty cases included in this study, different CNVs were detected in ten children (20%), in/outside the SHOX region. Moreover, in children with short stature, the expression level of miRNA-140 was significantly different from that of healthy controls.

Conclusions

This is one of the first studies that have assessed CNVs in the SHOX/PAR1 region in a group of Egyptian children with short stature. MLPA analysis of SHOX/PAR1 identified different CNVs in children with non-syndromic short stature, suggesting that the MLPA should be used as an initial screening technique in short children, as proper genetic diagnosis of these children leads to implementation of the appropriate therapeutic approach. Alterations in the levels of miRNA-140 in children with short stature suggest that changes in the expression levels of this miRNA are associated with the pathogenesis of short stature.

Detection of SHOX Gene Variations in Patients with Skeletal Abnormalities with or without Short Stature

OBJECTIVE

SHOX gene mutations constitute one of the genetic causes of short stature. The clinical phenotype includes variable degrees of growth impairment, such as Langer mesomelic dysplasia (LMD), Léri-Weill dyschondrosteosis (LWD) or idiopathic short stature (ISS). The aim of this study was to describe the clinical features and molecular results of SHOX deficiency in a group of Turkish patients who had skeletal findings with and without short stature.

METHODS

Forty-six patients with ISS, disproportionate short stature or skeletal findings without short stature from 35 different families were included. SHOX gene analysis was performed using Sanger sequencing and multiplex ligation-dependent probe amplification analysis.

RESULTS

Three different point mutations (two nonsense, one frameshift) and one whole SHOX gene deletion were detected in 15 patients from four different families. While 4/15 patients had LMD, the remaining patients had clinical features compatible with LWD. Madelung’s deformity, cubitus valgus, muscular hypertrophy and short forearm were the most common phenotypic features, as well as short stature. Additionally, hearing loss was detected in two patients with LMD.

CONCLUSION

This study has presented the clinical spectrum and molecular findings of 15 patients with SHOX gene mutations or deletions. SHOX deficiency should be especially considered in patients who have disproportionate short stature or forearm anomalies with or without short stature. Although most of the patients had partial or whole gene deletions, SHOX gene sequencing should be performed in suspected cases. Furthermore, conductive hearing loss may rarely accompany these clinical manifestations.

A new approach to the diagnosis of short stature

Growth is the task of children. We review the normal process of linear growth from the fetus through adolescence and note that growth is the result of age- and gender-dependent interactions among key genetic, environmental, dietary, socioeconomic, developmental, behavioral, nutritional, metabolic, biochemical, and hormonal factors. We then define the wide range of normative data at each stage of growth and note that a pattern within this range is generally indicative of good general health and that growth significantly slower than this range may lead to growth faltering and subsequent short stature. Although not often emphasized, we detail how to properly measure infants and children because height velocity is usually determined from two height measurements (both relatively large values) to calculate the actual height velocity (a relatively much smaller number in comparison). Traditionally the physiology of growth has been taught from an endocrine-centric point-of-view. Here we review the hypothalamic-pituitary-end organ axes for the GH/IGF-1 and gonadal steroid hormones (hypothalamic-pituitary-gonadal axis), both during "mini"-puberty as well as at puberty. However, over the past few decades much more emphasis has been placed on the growth plate and its many interactions with the endocrine system but also with its own intrinsic physiology and gene mutations. These latter, whether individually (large effect size) or in combination with many others including endocrine system-based, may account in toto for meaningful differences in adult height. The clinical assessment of children with short stature includes medical, social and family history, physical exam and importantly proper interpretation of the growth curve. This analysis should lead to judicious use of screening laboratory and imaging tests depending on the pre-test probability (Bayesian inference) of a particular diagnosis in that child. In particular for those with no pathological features in the history and physical exam and a low, but normal height velocity, may lead only to a bone age exam and reevaluation (re-measurement), perhaps 6 months later. he next step depends on the comfort level of the primary care physician, the patient, and the parent; that is, whether to continue with the evaluation with more directed, more sophisticated testing, again based on Bayesian inference or to seek consultation with a subspecialist pediatrician based on the data obtained. This is not necessarily an endocrinologist. The newest area and the one most in flux is the role for genetic testing, given that growth is a complex process with large effect size for single genes but smaller effect sizes for multiple other genes which in the aggregate may be relevant to attained adult height. Genetics is a discipline that is rapidly changing, especially as the cost of exome or whole gene sequencing diminishes sharply. Within a decade it is quite likely that a genetic approach to the evaluation of children with short stature will become the standard, truncating the diagnostic odyssey and be cost effective as fewer biochemical and imaging studies are required to make a proper diagnosis.

Clinical and Genetic Characteristics of 23 Korean Patients with Haploinsufficiency of the Short-stature Homeobox-containing Gene

BACKGROUND

The short-stature homeobox-containing gene (SHOX) is one of the major growth genes in humans. The clinical spectrum of SHOX haploinsufficiency ranges from Léri-Weill dyschondrosteosis to idiopathic short stature. Herein, we describe the clinical and genetic characteristics of 23 Korean patients with SHOX deficiency disorders.

METHODS

Medical records of 23 patients (19 females and 4 males) from 15 unrelated families who were genetically confirmed to have SHOX deficiency were retrospectively reviewed. SHOX gene deletions or mutations were determined by sequence analyses using multiplex ligation-dependent probe amplification, chromosomal microarray, and/or Sanger sequencing methods.

RESULTS

In the 15 families, 9 probands were de novo cases. All 23 patients showed mesomelia. Madelung deformity and tibia vara were observed in 13 (56.5%) and 3 (13.1%) patients, respectively. Genetically, 11 (73.3%) of the 15 families showed SHOX deletions of various sizes, and the other 4 families harboured SHOX sequence variants. Four patients had undergone orthopaedic surgeries (3 for tibia vara and 1 for Madelung deformity). Among 7 patients who had received growth hormone treatment for ≥1 year, 5 showed good responses, with a median first-year change-in-height standard deviation score of +0.6. There were no significant differences in the clinical characteristics of the deletion and point mutation groups.

CONCLUSIONS

A high index of suspicion and the genetic confirmation of SHOX deficiency are helpful for the timely management of the condition and are needed to provide genetic counselling to the family members of the patients.

Turner Syndrome Growth Charts: A Western India Experience

BACKGROUND AND OBJECTIVES

Disease specific growth charts are useful to monitor growth and disease progress in specific disorders such as Turner syndrome. As there is a paucity of data on spontaneous growth of Indian girls with Turner syndrome, the objectives were to construct reference curves for height and assess height velocity in Indian girls with Turner syndrome from 5 centers from western India.

MATERIAL AND METHODS

Three hundred forty-eight readings of height and weight on 113 genetically proven girls with Turner Syndrome from 5 centers from western India were collected and retrospectively analyzed. Data were collected over the last 2 decades (GH treatment naive girls were included). The method described by Lyon et al. was used to compute smoothed standard deviations and percentiles for height. For computing growth velocities, longitudinal data were used on 104 untreated girls (longitudinal readings for height for a minimum of 3 years were used). Midparental height z scores (MPHZ) were computed.

RESULTS

In girls with Turner syndrome, the mean adult height was found to be 140.1 cm. Height velocity was low at all ages compared to normal girls with a notable difference beyond the age of 10 years where normally, a growth spurt is expected. The MPH Z-score correlated positively with the height Z-score. The 3^rd, 50^th, and 97^th height percentiles of Turner girls at all ages were lower than normal girls' charts.

CONCLUSION

Turner syndrome charts for height are presented; these charts may be used to monitor growth in girls with Turner syndrome.

Genes that escape from X-chromosome inactivation: Potential contributors to Klinefelter syndrome

One of the two X chromosomes in females is epigenetically inactivated, thereby compensating for the dosage difference in X-linked genes between XX females and XY males. Not all X-linked genes are completely inactivated, however, with 12% of genes escaping X chromosome inactivation and another 15% of genes varying in their X chromosome inactivation status across individuals, tissues or cells. Expression of these genes from the second and otherwise inactive X chromosome may underlie sex differences between males and females, and feature in many of the symptoms of XXY Klinefelter males, who have both an inactive X and a Y chromosome. We review the approaches used to identify genes that escape from X-chromosome inactivation and discuss the nature of their sex-biased expression. These genes are enriched on the short arm of the X chromosome, and, in addition to genes in the pseudoautosomal regions, include genes with and without Y-chromosomal counterparts. We highlight candidate escape genes for some of the features of Klinefelter syndrome and discuss our current understanding of the mechanisms underlying silencing and escape on the X chromosome as well as additional differences between the X in males and females that may contribute to Klinefelter syndrome.

The Challenge of Defining and Investigating the Causes of Idiopathic Short Stature and Finding an Effective Therapy

Idiopathic short stature (ISS) comprises a wide range of conditions associated with short stature that elude the conventional diagnostic work-up and are often caused by still largely unknown genetic variants. In the last decade, the improvement of diagnostic techniques has led to the discovery of causal mutations in genes involved in the function of the growth hormone (GH)/insulin-like growth factor-I (IGF-I) axis as well as in growth plate physiology. However, many cases of ISS remain idiopathic. In the future, the more frequent identification of the underlying causes will allow a better stratification of subjects and offer a tailored management. GH therapy has been proposed and approved in some countries for the treatment of children with ISS. To improve the efficacy of GH therapy, trials with GH combined with GnRH agonists, aromatase inhibitors, and even IGF-I have been conducted. This review aims to revise the current definition of ISS and discuss the management of children with ISS on the basis of the most recent evidence.

High frequency of pathogenic ACAN variants including an intragenic deletion in selected individuals with short stature

CONTEXT

Defining the underlying etiology of idiopathic short stature (ISS) improves the overall management of an individual.

OBJECTIVE

To assess the frequency of pathogenic ACAN variants in selected individuals.

DESIGN

The single-center cohort study was conducted at a tertiary university children's hospital. From 51 unrelated patients with ISS, the 16 probands aged between 3 and 18 years (12 females) with advanced bone age and/or autosomal dominant inheritance pattern of short stature were selected for the study. Fifteen family members of ACAN-positive probands were included. Exome sequencing was performed in all probands, and additional copy number variation (CNV) detection was applied in selected probands with a distinct ACAN-associated phenotype.

RESULTS

Systematic phenotyping of the study cohort yielded 37.5% (6/16) ACAN-positive probands, with all novel pathogenic variants, including a 6.082 kb large intragenic deletion, detected by array comparative genomic hybridization (array CGH) and exome data analysis. All variants were co-segregated with short stature phenotype, except in one family member with the intragenic deletion who had an unexpected growth pattern within the normal range (-0.5 SDS). One patient presented with otosclerosis, a sign not previously associated with aggrecanopathy.

CONCLUSIONS

ACAN pathogenic variants presented a common cause of familial ISS. The selection criteria used in our study were suggested for a personalized approach to genetic testing of the ACAN gene in clinical practice. Our results expanded the number of pathogenic ACAN variants, including the first intragenic deletion, and suggested CNV evaluation in patients with typical clinical features of aggrecanopathy as reasonable. Intra-familial phenotypic variability in growth patterns should be considered.

Genetic syndromes associated with isolated fetal growth restriction

Early onset fetal growth restriction (FGR) may be due to impaired placentation, environmental or toxic exposure, congenital infections or genetic abnormalities. Remarkable research, mainly based on retrospective series, has been published on the diverse genetic causes. Those have become more and more relevant with the improvement in the accuracy of the analysis techniques and the rising of breakthrough genomewide methods such as the whole genome sequencing. However, no publication has presented an integrated view of management of those fetuses with an early and severe affection. In this review, we explored to which extent genetic syndromes can cause FGR fetuses without structural defects. The most common chromosomal abnormalities (Triploidies and Trisomy 18), submicroscopic chromosomal anomalies (22q11.2 microduplication syndrome) and single gene disorders (often associated with mild ultrasound findings) related to early and severe FGR had been analysed. Finally, we addressed the impact of epigenetic marks on fetal growth, a matter of growing importance. At the end of this review, we should be able to provide an adequate counseling to parents in terms of diagnosis, prognosis and management of those pregnancies.

Microphthalmia, Linear Skin Defects, Callosal Agenesis, and Cleft Palate in a Patient with Deletion at Xp22.3p22.2

The authors describe the clinical findings observed in a Brazilian girl that are suggestive of microphthalmia and linear skin defects (MLS) also known as MIDAS syndrome (OMIM #309801). She also presented with short stature, agenesis of corpus callosum, cleft palate, enamel defects, and genitourinary anomalies, which are rarely reported within the clinical spectrum of MLS. The 11,5 Mb deletion in Xp22.3p22.2 observed in the patient includes the entire HCCS gene (responsible for the MLS phenotype) and also encompasses several other genes involved with behavioral phenotypes, craniofacial and central nervous system development such as MID1, NLGN4X, AMELX , ARHGAP6, and TBL1X. The whole clinical features of our proband possibly represents an unusual MLS syndromic phenotype caused by an Xp22.3p22.2 continuous gene deletion.

Heterozygous Deletion of the SHOX Gene Enhancer in two Females With Clinical Heterogeneity Associating With Skewed XCI and Escaping XCI

Skewed X-chromosome inactivation (XCI) plays an important role in the phenotypic heterogeneity of X-linked disorders. However, the role of skewed XCI in XCI-escaping gene SHOX regulation is unclear. Here, we focused on a heterozygous deletion of SHOX gene enhancer with clinical heterogeneity. Using SNP array, we detected that the female proband with Leri-Weill dyschondrosteosis (LWD) carried an 857 kb deletion on Xp22.3 (encompassing SHOX enhancer) and a 5,707 kb large-fragment deletion on Xq25q26. XCI analysis revealed that the X-chromosome with the Xq25q26 large-fragment deletion was completely inactivated, which forced the complete activation of the other X-chromosome carrying SHOX enhancer deletion. While the Xp22.3 deletion locates on the escaping XCI region, under the combined action of skewed XCI and escaping XCI, transcription of SHOX gene was mainly from the activated X-chromosome with SHOX enhancer defect, involving in the formation of LWD phenotype. Interestingly, this SHOX enhancer deletion was inherited from her healthy mother, who also demonstrated completely skewed XCI. However, the X-chromosome with SHOX enhancer deletion was inactivated, and the normal X-chromosome was activated. Combing with escaping XCI, her phenotype was almost normal. In summary, this study was a rare report of SHOX gene enhancer deletion in a family with clinical heterogeneity due to skewed inactivation of different X-chromosomes, which can help in the genetic counseling and prenatal diagnosis of disorders in females with SHOX defect.

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.

Complex Phenotypes: Mechanisms Underlying Variation in Human Stature

PURPOSE OF REVIEW

The goal of the review is to provide a comprehensive overview of the current understanding of the mechanisms underlying variation in human stature.

RECENT FINDINGS

Human height is an anthropometric trait that varies considerably within human populations as well as across the globe. Historically, much research focus was placed on understanding the biology of growth plate chondrocytes and how modifications to core chondrocyte proliferation and differentiation pathways potentially shaped height attainment in normal as well as pathological contexts. Recently, much progress has been made to improve our understanding regarding the mechanisms underlying the normal and pathological range of height variation within as well as between human populations, and today, it is understood to reflect complex interactions among a myriad of genetic, environmental, and evolutionary factors. Indeed, recent improvements in genetics (e.g., GWAS) and breakthroughs in functional genomics (e.g., whole exome sequencing, DNA methylation analysis, ATAC-sequencing, and CRISPR) have shed light on previously unknown pathways/mechanisms governing pathological and common height variation. Additionally, the use of an evolutionary perspective has also revealed important mechanisms that have shaped height variation across the planet. This review provides an overview of the current knowledge of the biological mechanisms underlying height variation by highlighting new research findings on skeletal growth control with an emphasis on previously unknown pathways/mechanisms influencing pathological and common height variation. In this context, this review also discusses how evolutionary forces likely shaped the genomic architecture of height across the globe.

Genetics of Growth Disorders-Which Patients Require Genetic Testing?

The second 360° European Meeting on Growth Hormone Disorders, held in Barcelona, Spain, in June 2017, included a session entitled Pragmatism vs. Curiosity in Genetic Diagnosis of Growth Disorders, which examined current concepts of genetics and growth in the clinical setting, in terms of both growth failure and overgrowth. For patients with short stature, multiple genes have been identified that result in GH deficiency, which may be isolated or associated with additional pituitary hormone deficiencies, or in growth hormone resistance, primary insulin-like growth factor (IGF) acid-labile subunit deficiency, IGF-I deficiency, IGF-II deficiency, IGF-I resistance, and primary PAPP-A2 deficiency. While genetic causes of short stature were previously thought to primarily be associated with the GH-IGF-I axis, it is now established that multiple genetic anomalies not associated with the GH-IGF-I axis can result in short stature. A number of genetic anomalies have also been shown to be associated with overgrowth, some of which involve the GH-IGF-I axis. In patients with overgrowth in combination with an intellectual disability, two predominant gene families, the epigenetic regulator genes, and PI3K/AKT pathway genes, have now been identified. Specific processes should be followed for decisions on which patients require genetic testing and which genes should be examined for anomalies. The decision to carry out genetic testing should be directed by the clinical process, not merely for research purposes. The intention of genetic testing should be to direct the clinical options for management of the growth disorder.