Health-related quality of life in children and adolescents with Marfan syndrome or related disorders: a controlled cross-sectional study.

BACKGROUND: This cross-sectional controlled study aims to assess health-related quality of life (HRQoL) of children and adolescents with a molecular diagnosis of Marfan syndrome (MFS) or related disorders and to evaluate the factors associated with HRQoL in this population. Sixty-three children with MFS and 124 age- and sex-matched healthy children were recruited. HRQoL was assessed using the Pediatric Quality of Life Inventory (PedsQL™) generic questionnaire. The correlation between HRQoL scores and the different continuous parameters (age, body mass index, disease severity, systemic score, aortic sinus diameter, and aerobic physical capacity) was evaluated using Pearson's or Spearman's coefficient. A multiple linear regression analysis was performed on the two health summary self-reported PedsQL™ scores (physical and psychosocial) to identify the factors associated with HRQoL in the MFS group. RESULTS: Except for emotional functioning, all other domains of HRQoL (psychosocial and physical health, social and school functions) were significantly lower in children with MFS compared to matched healthy children. In the MFS group, the physical health summary score was significantly lower in female than in male patients (self-report: absolute difference [95%CI] = -8.7 [-17.0; -0.47], P = 0.04; proxy-report: absolute difference [95%CI] = -8.6 [-17.3; 0.02], P = 0.05) and also negatively correlated with the systemic score (self-report: R = -0.24, P = 0.06; proxy-report: R = -0.29, P = 0.03) and with the height Z-score (proxy-report: R = -0.29, P = 0.03). There was no significant difference in the physical health summary scores between the different genetic subgroups. In the subgroup of 27 patients who performed a cardiopulmonary exercise test, self- and proxy-reported physical health summary scores were highly correlated with their aerobic physical capacity assessed by peak oxygen consumption (VO2max) and ventilatory anaerobic threshold (VAT). In the multivariate analysis, the most important independent predictors of decreased physical health were increased height, decreased body mass index, decreased VAT and use of prophylactic therapy. CONCLUSIONS: This study reports an impaired HRQoL in children and adolescents with MFS or related conditions, in comparison with matched healthy children. Educational and rehabilitation programs must be developed and evaluated to improve exercise capacity and HRQoL in these patients. TRIAL REGISTRATION: ClinicalTrials.gov, NCT03236571 . Registered 28 July 2017.

Novel therapeutic perspectives in Noonan syndrome and RASopathies.

Noonan syndrome belongs to the family of RASopathies, a group of multiple congenital anomaly disorders caused by pathogenic variants in genes encoding components or regulators of the RAS/mitogen-activated protein kinase (MAPK) signalling pathway. Collectively, all these pathogenic variants lead to increased RAS/MAPK activation. The better understanding of the molecular mechanisms underlying the different manifestations of NS and RASopathies has led to the identification of molecular targets for specific pharmacological interventions. Many specific agents (e.g. SHP2 and MEK inhibitors) have already been developed for the treatment of RAS/MAPK-driven malignancies. In addition, other molecules with the property of modulating RAS/MAPK activation are indicated in non-malignant diseases (e.g. C-type natriuretic peptide analogues in achondroplasia or statins in hypercholesterolemia).  Conclusion: Drug repositioning of these molecules represents a challenging approach to treat or prevent medical complications associated with RASopathies. What is Known: • Noonan syndrome and related disorders are caused by pathogenic variants in genes encoding components or regulators of the RAS/mitogen-activated protein kinase (MAPK) signalling pathway, resulting in increased activation of this pathway. • This group of disorders is now known as RASopathies and represents one of the largest groups of multiple congenital anomaly diseases known. What is New: • The identification of pathophysiological mechanisms provides new insights into the development of specific therapeutic strategies, in particular treatment aimed at reducing RAS/MAPK hyperactivation. • Drug repositioning of specific agents already developed for the treatment of malignant (e.g. SHP2 and MEK inhibitors) or non-malignant diseases (e.g. C-type natriuretic peptide analogues in achondroplasia or statins in hypercholesterolaemia) represents a challenging approach to the treatment of RASopathies.

Adult height improved over decades in patients with X-linked hypophosphatemia: a cohort study.

OBJECTIVES: The aim of this study is to analyze height after cessation of growth (final height [FH]) and its evolution over the last decades in X-linked hypophosphatemia (XLH) patients in France, as the data on natural history of FH in XLH are lacking. DESIGN: We performed a retrospective observational study in a large cohort of French XLH patients with available data on FH measurements. MATERIALS AND METHODS: We divided patients into 3 groups according to their birth year: group 1 born between 1950 and 1974, group 2 born between 1975 and 2000, and group 3 born between 2001 and 2006, respectively, and compared their FHs. RESULTS: A total of 398 patients were included. Mean FHs were the following: for group 1, -2.31 ± 1.11 standard deviation score (SDS) (n = 127), 156.3 ± 9.7 cm in men and 148.6 ± 6.5 cm in women; for group 2, -1.63 ± 1.13 SDS (n = 193), 161.6 ± 8.5 cm in men and 153.1 ± 7.2 cm in women; and for group 3, -1.34 ± 0.87 SDS (n = 78), 165.1 ± 5.5 cm in men and 154.7 ± 6 cm in women. We report a significant increase in mean FH SDS over 3 generations of patients, for both men and women (P < .001). Final height SDS in male (-2.08 ± 1.18) was lower than in female (-1.70 ± 1.12) (P = .002). CONCLUSION: The FH of XLH patients in France increased significantly over the last decades. Even though men's FHs improved more than women's, men with XLH remain shorter reflecting a more severe disease phenotype. While the results are promising, most patients with XLH remain short leaving room for improvement.

Clinical heterogeneity of NADSYN1-associated VCRL syndrome.

The NADSYN1 gene [MIM*608285] encodes the NAD synthetase 1 enzyme involved in the final step of NAD biosynthesis, crucial for cell metabolism and organ embryogenesis. Perturbating the role of NAD biosynthesis results in the association of vertebral, cardiac, renal, and limb anomalies (VCRL). This condition was initially characterized as severe with perinatal lethality or developmental delay and complex malformations in alive cases. Sixteen NADSYN1-associated patients have been published so far. This study illustrates the wide phenotypic variability in NADSYN1-associated NAD deficiency disorder. We report the clinical and molecular findings in three novel cases, two of them being siblings with the same homozygous variant and presenting with either a very severe prenatal lethal or a mild phenotypic form. In addition to an exhaustive literature, we validate the expansion of the spectrum of NAD deficiency disorder. Our findings indicate that NAD deficiency disorder should be suspected not only in the presence of the full spectrum of VCRL, but even a single of the aforementioned organs is affected. Decreased plasmatic levels of NAD should then strongly encourage the screening for any of the genes responsible for a NAD deficiency disorder.

Obesity, Overweight, and Pituitary Stalk Interruption Syndrome in Children and Young Adults.

CONTEXT: Pituitary stalk interruption syndrome (PSIS) is rare in the pediatric population. It combines ectopic posterior pituitary stalk interruption and anterior pituitary hypoplasia with hormonal deficiencies. The phenotype is highly heterogeneous and obesity/overweight seems to be underreported in the literature. OBJECTIVE: To identify patients with PSIS and obesity or overweight, describe their phenotype, and compare them with patients with PSIS without overweight/obesity. METHODS: Sixty-nine children and young adults with PSIS in a Toulouse cohort from 1984 to 2019 were studied. We identified 25 obese or overweight patients (OB-OW group), and 44 were nonobese/overweight (NO group). Then the groups were compared. RESULTS: All cases were sporadic. The sex ratio was 1.6. The main reason for consultation in both groups was growth retardation (61% in OB-OW group, 77% in NO group). History of neonatal hypoglycemia was more common in the OB-OW than in the NO group (57% vs 14%, P = .0008), along with extrapituitary malformations (64% vs 20%, P < 0001). The incidence of caesarean section was higher in the OB-OW group (52%) than in the NO group (23%), although not significant (P = .07). CONCLUSION: Patients with PSIS who are obese/overweight display interesting phenotypic differences that suggest hypothalamic defects. Studies are needed that include additional information on hormonal levels, particularly regarding oxytocin and ghrelin.

IGSF1 mutations are the most frequent genetic aetiology of thyrotropin deficiency.

Design: Thyroid-stimulating hormone deficiency (TSHD) is a rare disease. It may be isolated, secondary to abnormalities of genes involved in TSH biosynthesis, or associated with other pituitary deficits or abnormalities of genes involved in pituitary ontogenesis. Several genes are involved in thyrotroph development and function. Objective: Our aim was to determine the genetic causes of TSHD, either isolated (ITSHD) or associated with somatotroph deficiency (TSHD-GHD), in the cohort of patients from the GENHYPOPIT network. Methods: Next-generation sequencing (NGS) analyses were performed as a panel of genes on a cohort of patients with non-syndromic ITSHD or TSHGHD. The variants were classified according to the American College of Medical Genetics classification reviewed by the NGS-Diag network and correlated with the phenotype. Class 3, 4, and 5 single-nucleotide variants were checked by Sanger sequencing and copy number variants by multiplex ligation-dependent probe amplification (MLPA). Results: A total of 64 index cases (22 ITSHD and 42 TSHD-GHD) were included in this cohort. A genetic cause was identified in 26.5% of patients, with 36.3% in the ITSHD group (variants in TSHß and IGSF1) and 21.4% in TSHD-GHD (variants in IGSF1, TSHß, TRHR, GH1, POU1F1, and PROP1). Among the pathogenic and likely pathogenic variants identified, 42% were in IGSF1, including six not previously reported. Conclusion: Our results show that IGSF1 variants represent the most frequent aetiology of TSH deficiency. Despite a systematic NGS approach and the identification of new variants, most patients remain without a molecular diagnosis. Larger scale studies, such as exome or genome studies, should be considered in the future.

The Tyrosine Phosphatase SHP2: A New Target for Insulin Resistance?

The SH2 containing protein tyrosine phosphatase 2(SHP2) plays essential roles in fundamental signaling pathways, conferring on it versatile physiological functions during development and in homeostasis maintenance, and leading to major pathological outcomes when dysregulated. Many studies have documented that SHP2 modulation disrupted glucose homeostasis, pointing out a relationship between its dysfunction and insulin resistance, and the therapeutic potential of its targeting. While studies from cellular or tissue-specific models concluded on both pros-and-cons effects of SHP2 on insulin resistance, recent data from integrated systems argued for an insulin resistance promoting role for SHP2, and therefore a therapeutic benefit of its inhibition. In this review, we will summarize the general knowledge of SHP2's molecular, cellular, and physiological functions, explaining the pathophysiological impact of its dysfunctions, then discuss its protective or promoting roles in insulin resistance as well as the potency and limitations of its pharmacological modulation.

[Delayed growth in height and weight]. / Le retard de croissance staturo-pondérale.

Assessing weight and height development is a key element of pediatric follow-up. Growth retardation, even in isolation, may be the first symptom of a chronic disease and should therefore always be investigated. Many chronic diseases can be responsible and in most cases, diagnosis and management of the disease will minimize the impact on statural growth. The reconstruction of growth curves on the health record is essential to obtain a vision of the growth kinetics of the child and to orient the diagnosis. The study of the evolution of the ratio between weight and height is an essential point in the diagnostic process.

Gonadal function in Noonan syndrome.

Noonan syndrome (NS) is a relatively common developmental disorder characterised by the association of craniofacial abnormalities, congenital heart defects, short stature and skeletal abnormalities, variable developmental delay/learning disability, and predisposition to certain cancers. NS is caused by germline mutations in genes encoding components or regulators of the RAS/mitogen-activated protein kinase (MAPK) signaling pathway. Although abnormalities in the hypothalamic-pituitary-gonadal axis have long been reported in NS patients, there is only scarce published data on this subject. Puberty is usually delayed of about two years for both boys and girls with NS. However, in the majority of patients, it starts spontaneously suggesting a normal hypothalamic - pituitary input. The lower fat mass usually observed in NS patients may influence the timing of puberty. Although there is almost no reliable data on this issue, it is usually considered that fertility is not affected in NS females. In contrast, primary testicular insufficiency, predominant on Sertoli cell function, is reported in NS males. However, the exact frequency of infertility in adult males is unknown. More generally, although the features of NS are well described during childhood, little is known about the progression of the disease in adulthood. Prospective long-term follow-up studies are required to further investigate gonadal function and fertility in NS adults and to clarify the long-term follow-up of these patients.

Diagnostic yield of bone fragility gene panel sequencing in children and young adults referred for idiopathic primary osteoporosis at a single regional reference centre.

AIM: To describe the presenting features, bone characteristics and molecular genetics in a large monocentric cohort of children and young adults with idiopathic primary osteoporosis. METHODS: Sixty-six patients (19 children, 47 adults; 28 males, 38 females; age at referral: 3.8 to 65 years) diagnosed with primary osteoporosis were included in this study; patients with features of osteogenesis imperfecta or other known syndromes associated with osteoporosis were excluded. For each patient, the following data were collected by retrospective chart review: family and personal history of fracture and osteoporosis, mineral homeostasis parameters and markers of bone formation and resorption, bone mineral density (BMD) of the lumbar spine (LS-BMD), the total body less head (TB-BMD), and total hip levels (TH-BMD) measured by DXA. As part of the initial assessment process, a bone fragility gene panel sequencing was performed in all of these patients. RESULTS: There was a higher predominance of males in the children (63%) and of females in the adults (66%) (p = 0.030). Compared to the adults, the children had a significantly lower frequency of vertebral fractures (26 vs 57%, p = 0.022) and a higher frequency of peripheral fractures (84 vs 53%; p = 0.019). Bone fragility gene panel sequencing allowed the identification of the heterozygous pathogenic variant in 27% of patients (most frequently in LRP5, WNT1 and COL1A1 or 2 genes) and the heterozygous p.(Val667Met) LRP5 variant in 11% of them. The frequency of pathogenic variants tended to be higher in the children compared to the adults without reaching statistical significance (42 vs 19%; p = 0.053). The frequency of the p.(Val667Met) LRP5 variant was similar in children and adults. No significant differences were found regarding the various clinical, biological and radiological characteristics of the patients according to genotype. CONCLUSION: In this study, we reported the presenting features and bone characteristics in a large cohort of children and young adults with idiopathic primary osteoporosis. Bone fragility gene panel sequencing allowed the identification of genetic variants in a significant proportion of these patients. Molecular diagnosis in these patients is important in order to be able to offer genetic counselling and organise patient management.

Outcomes in growth hormone-treated Noonan syndrome children: impact of PTPN11 mutation status.

Introduction: Mutations in PTPN11 are associated with Noonan syndrome (NS). Although the effectiveness of growth hormone therapy (GHT) in treating short stature due to NS has been previously demonstrated, the effect of PTPN11 mutation status on the long-term outcomes of GHT remains to be elucidated. Methods: This analysis included pooled data from the observational American Norditropin Studies: Web-Enabled Research Program (NCT01009905) and the randomized, double-blinded GHLIQUID-4020 clinical trial (NCT01927861). Pediatric patients with clinically diagnosed NS and confirmed PTPN11mutation status were eligible for inclusion. The effectiveness analysis included patients who were GHT-naïve and pre-pubertal at GHT start. Growth outcomes and safety were assessed over 4 years of GHT (Norditropin®, Novo Nordisk A/S). Results: A total of 69 patients were included in the effectiveness analysis (71% PTPN11 positive). The proportion of females was 32.7 and 30.0% in PTPN11-positive and negative patients, respectively, and mean age at GHT start was 6.4 years in both groups. Using general population reference data, after 4 years of GHT, the mean (s.d.) height SD score (HSDS) was -1.9 (1.1) and -1.7 (0.8) for PTPN11-positive and PTPN11-negative patients, respectively, with no statistical difference observed between groups. The mean (s.d.) change in HSDS at 4 years was +1.3 (0.8) in PTPN11-positive patients and +1.5 (0.7) in PTPN11-negative patients (no significant differences between groups). Safety findings were consistent with previous analyses. Conclusions: GHT resulted in improved growth outcomes over 4 years in GHT-naïve, pre-pubertal NS patients, irrespective of PTPN11 mutation status.

Noonan syndrome: improving recognition and diagnosis.

Noonan syndrome (NS) is a mostly dominantly inherited disorder affecting 1:1000 to 1:2500 live births. The phenotype varies in severity and can involve multiple organ systems over a patient's lifetime. Diagnosis is based on a combination of features, including typical facial features, short stature, skeletal abnormalities, presence of cardiac defects, mild developmental delay, cryptorchidism, lymphatic dysplasia and a family history of NS. The phenotype varies from oligosymptomatic adults without significant medical issues to severely affected neonates with life-threatening heart disease. Early, accurate diagnosis is important for individualised management and to optimise developmental and long-term outcomes, but mildly affected patients often go undiagnosed for both healthcare provider (HCP)-related and patient-related reasons. Lack of awareness of NS among HCPs means that some do not recognise the condition, particularly in mildly affected patients and families. Some families do not want to receive a diagnosis that medicalises a condition that may account for family traits (eg, distinctive facial features and short stature), particularly when a child's physical and cognitive development may be satisfactory. As for any condition with lifelong effects on multiple organ systems, a multidisciplinary approach provides the best care. It is proposed that increasing awareness of NS among non-specialist HCPs and other professionals could help direct a parent/carer to seek specialist advice and increase the number of NS diagnoses, with the potential to optimise lifelong patient outcomes. Non-specialists do not need to become experts in either diagnosis or treatment; however, early recognition of NS and referral to an appropriate specialist is important.

Joint involvement in Noonan syndrome. A retrospective paediatric descriptive study.

OBJECTIVES: Noonan syndrome is a rare genetic disorder characterized mainly by congenital heart disease, occasional intellectual disability, and varied orthopaedic, rheumatological and haematologic anomalies. Despite potentially serious functional consequences, joint involvement has been rarely studied in the literature. Our objective was to perform a retrospective study evaluating the prevalence and characteristics of joint involvement in Noonan syndrome. METHODS: We recorded articular symptoms, including their type and frequency, in patients with Noonan syndrome followed up in French hospitals. Patients were included if the diagnosis was confirmed before the age of 20 based on the van der Burgt criteria or genetic analysis. Data are presented as frequencies or medians (ranges), and patient groups were compared using chi-square or Fisher tests. RESULTS: Seventy-one patients were included from 4 centres. The average age was 12.5 years (range: 2-36). Musculoskeletal pain was found in 18 patients (25%) and joint stiffness in 10 (14%) located in the wrists, elbows, ankles, knees and hips, which was usually bilateral. Only one destructive form was described (multiple villonodular synovitis and a giant cell lesion of the jaw). There were no cases of systemic lupus erythaematosus (SLE) or other autoimmune arthritis. Raynaud's phenomenon was observed in 3 patients. Only 50% of joint complaints led to additional exploration. SOS1 mutations (P<0.05) and treatment with growth hormone (GH) (P<0.05) were the only factors significantly related to musculoskeletal pain. Patients treated with GH did not have more SOS1 mutations. Patients experiencing pain were not more likely to experience stiffness, joint hypermobility, or coagulation abnormalities. CONCLUSION: Joint manifestations were frequent in Noonan syndrome, predominant in large joints, and rarely explored. Multiple villonodular synovitis is characteristic but rare. Auto-immune disorders were not described in this cohort. A more multidisciplinary approach could be recommended for the early detection of possibly disabling rheumatologic manifestations.

Management of cardiac aspects in children with Noonan syndrome - results from a European clinical practice survey among paediatric cardiologists.

BACKGROUND: The majority of children with Noonan syndrome (NS) or other diseases from the RASopathy spectrum suffer from congenital heart disease. This study aims to survey cardiac care of this patient cohort within Europe. METHODS: A cross-sectional exploratory survey assessing the treatment and management of patients with NS by paediatric endocrinologists, cardiologists and clinical geneticists was developed. This report details responses of 110 participating paediatric cardiologists from multiple countries. RESULTS: Most paediatric cardiologists responding to the questionnaire were associated with university hospitals, and most treated <10 patients/year with congenital heart disease associated with the NS spectrum. Molecular genetic testing for diagnosis confirmation was initiated by 81%. Half of the respondents reported that patients with NS and congenital heart disease typically present <1y of age, and that a large percentage of affected patients require interventions and pharmacotherapy early in life. A higher proportion of infant presentation and need for pharmacotherapy was reported by respondents from Germany and Sweden than from France and Spain (p = 0.031; p = 0.014; Fisher's exact test). Older age at first presentation was reported more from general hospitals and independent practices than from university hospitals (p = 0.031). The majority of NS patients were followed at specialist centres, but only 37% reported that their institution offered dedicated transition clinic to adult services. Very few NS patients with hypertrophic cardiomyopathy (HCM) were reported to carry implantable cardioverter defibrillators for sudden cardiac death prevention. Uncertainty was evident in regard to growth hormone treatment in patients with NS and co-existing HCM, where 13% considered it not a contra-indication, 24% stated they did not know, but 63% considered HCM either a possible (20%) or definite (15%) contraindication, or a cause for frequent monitoring (28%). Regarding adverse reactions for patients with NS on growth hormone therapy, 5/19 paediatric cardiology respondents reported a total of 12 adverse cardiac events. CONCLUSIONS: Congenital heart disease in patients with NS or other RASopathies is associated with significant morbidity during early life, and specialty centre care is appropriate. More research is needed regarding the use of growth hormone in patients with NS with congenital heart disease, and unmet medical needs have been identified.

European Medical Education Initiative on Noonan syndrome: A clinical practice survey assessing the diagnosis and clinical management of individuals with Noonan syndrome across Europe.

INTRODUCTION: Noonan syndrome (NS) is a rare genetic disorder caused by mutations in genes encoding components of the RAS/mitogen-activated protein kinase (MAPK) signalling pathway. Patients with NS exhibit certain characteristic features, including cardiac defects, short stature, distinctive facial appearance, skeletal abnormalities, cognitive deficits, and predisposition to certain cancers. Here, a clinical practice survey was developed to learn more about differences in the diagnosis and management of this disease across Europe. The aim was to identify gaps in the knowledge and management of this rare disorder. MATERIALS AND METHODS: The European Medical Education Initiative on NS, which comprised a group of 10 experts, developed a 60-question clinical practice survey to gather information from European physicians on the diagnosis and clinical management of patients with diseases in the NS phenotypic spectrum. Physicians from three specialities (clinical genetics, paediatric endocrinology, paediatric cardiology) were invited to complete the survey by several national and European societies. Differences in answers provided by respondents between specialities and countries were analysed using contingency tables and the Chi-Squared test for independence. The Friedman's test was used for related samples. RESULTS: Data were analysed from 364 respondents from 20 European countries. Most respondents came from France (21%), Spain (18%), Germany (16%), Italy (15%), United Kingdom (8%) and the Czech Republic (6%). Respondents were distributed evenly across three specialities: clinical genetics (30%), paediatric endocrinology (40%) and paediatric cardiology (30%). Care practices were generally aligned across the countries participating in the survey. Delayed diagnosis did not emerge as a critical issue, but certain unmet needs were identified, including transition of young patients to adult medical services and awareness of family support groups. CONCLUSION: Data collected from this survey provide a comprehensive summary of the diagnosis and clinical management practices for patients with NS across different European countries.

WNT11, a new gene associated with early onset osteoporosis, is required for osteoblastogenesis.

Monogenic early onset osteoporosis (EOOP) is a rare disease defined by low bone mineral density (BMD) that results in increased risk of fracture in children and young adults. Although several causative genes have been identified, some of the EOOP causation remains unresolved. Whole-exome sequencing revealed a de novo heterozygous loss-of-function mutation in Wnt family member 11 (WNT11) (NM_004626.2:c.677_678dup p.Leu227Glyfs*22) in a 4-year-old boy with low BMD and fractures. We identified two heterozygous WNT11 missense variants (NM_004626.2:c.217G > A p.Ala73Thr) and (NM_004626.2:c.865G > A p.Val289Met) in a 51-year-old woman and in a 61-year-old woman, respectively, both with bone fragility. U2OS cells with heterozygous WNT11 mutation (NM_004626.2:c.690_721delfs*40) generated by CRISPR-Cas9 showed reduced cell proliferation (30%) and osteoblast differentiation (80%) as compared with wild-type U2OS cells. The expression of genes in the Wnt canonical and non-canonical pathways was inhibited in these mutant cells, but recombinant WNT11 treatment rescued the expression of Wnt pathway target genes. Furthermore, the expression of RSPO2, a WNT11 target involved in bone cell differentiation, and its receptor leucine-rich repeat containing G protein-coupled receptor 5 (LGR5), was decreased in WNT11 mutant cells. Treatment with WNT5A and WNT11 recombinant proteins reversed LGR5 expression, but Wnt family member 3A (WNT3A) recombinant protein treatment had no effect on LGR5 expression in mutant cells. Moreover, treatment with recombinant RSPO2 but not WNT11 or WNT3A activated the canonical pathway in mutant cells. In conclusion, we have identified WNT11 as a new gene responsible for EOOP, with loss-of-function variant inhibiting bone formation via Wnt canonical and non-canonical pathways. WNT11 may activate Wnt signaling by inducing the RSPO2-LGR5 complex via the non-canonical Wnt pathway.

Management of growth failure and other endocrine aspects in patients with Noonan syndrome across Europe: A sub-analysis of a European clinical practice survey.

AIM: To date, there is a lack of international guidelines regarding the management of the endocrine features of individuals with Noonan syndrome (NS). The aim was to develop a clinical practice survey to gather information on current treatment and management of these patients across Europe. MATERIALS AND METHODS: A group of 10 experts from three clinical specialities involved in the management of NS patients (clinical geneticists, paediatric endocrinologists, and paediatric cardiologists) developed a 60-question clinical practice survey. The questionnaire was implemented in Survey Monkey and sent to physicians from these three specialities via European/national societies. Contingency tables and the Chi-Squared test for independence were used to examine differences between specialities and countries. RESULTS: In total, responses of 364 specialists (paediatric endocrinologists, 40%; geneticists, 30%; paediatric cardiologists, 30%) from 20 European countries were analysed. While endocrinologists mostly referred to national growth charts for the general population, geneticists mostly referred to NS-specific growth charts. Approximately half of the endocrinologists perform growth hormone (GH) stimulation tests in short patients with low IGF1 levels. Two thirds of endocrinologists begin GH treatment for short patients in early childhood (4-6.9 years), and over half of them selected a threshold of -2 standard deviation score (SDS) according to national growth charts. The main concerns about GH treatment appear to be presence of hypertrophic cardiomyopathy (HCM) (59%), increased risk of malignancy (46%), and limited efficacy (31%). When asked if they consider HCM as a contraindication for GH treatment, one third of respondents skipped this question, and among those who replied, two thirds selected 'cannot answer', suggesting a high level of uncertainty. A total of 21 adverse cardiac responses to GH treatment were reported. Although most respondents had not encountered any malignancy during GH treatment, six malignancies were reported. Finally, about half of the endocrinologists expected a typical final height gain of 1-1.5 SDS with GH treatment. CONCLUSION: This survey describes for the first time the current clinical practice of endocrine aspects of NS across Europe and helps us to identify gaps in the management but also in the knowledge of this genetic disorder.

A +3 variant at a donor splice site leads to a skipping of the MYH11 exon 32, a recurrent RNA defect causing Heritable Thoracic Aortic Aneurysm and Dissection and/or Patent Ductus Arteriosus.

BACKGROUND: Pathogenic variants in MYH11 are associated with either heritable thoracic aortic aneurysm and dissection (HTAAD), patent ductus arteriosus (PDA) syndrome, or megacystis-microcolon-intestinal hypoperistalsis syndrome (MMIHS). METHODS AND RESULTS: We report a family referred for molecular diagnosis with HTAAD/PDA phenotype in which we found a variant at a non-conserved position of the 5' donor splice site of intron 32 of MYH11 potentially altering splicing (NM_002474.3:c.4578+3A>C). Although its cosegregation with disease was observed, it remained of unknown significance. Later, aortic surgery in the proband gave us the opportunity to perform a transcript analysis. This showed a skipping of the exon 32, an RNA defect previously reported to be translated to an in-frame loss of 71 amino acids and a dominant-negative effect in the smooth muscle myosin rod. This RNA defect is also reported in 3 other HTAAD/PDA pedigrees. CONCLUSION: This report confirms that among rare variants in MYH11, skipping of exon 32 is recurrent. This finding is of particular interest to establish complex genotype-phenotype correlations where some alleles are associated with autosomal dominant HTAAD/PDA, while others result in recessive or dominant visceral myopathies.

Low bone mass in Noonan syndrome children correlates with decreased muscle mass and low IGF-1 levels.

Although musculoskeletal abnormalities have long been described in patients with Noonan syndrome (NS), only a few studies have investigated the bone status of these patients. The aim of this retrospective observational study was to describe the bone health of children with NS. Thirty-five patients with a genetically confirmed diagnosis of NS were enrolled. We analyzed the axial skeleton (lumbar spine) using dual energy X-ray absorptiometry and the appendicular skeleton (hand) with the BoneXpert system. Bone metabolism markers, including mineral homeostasis parameters, serum 25-hydroxy vitamin D (25-OHD) levels and markers of bone formation and resorption were also reported. Compared to the general population, axial and appendicular bone mass was significantly decreased in children with NS (p < 0.0001). Serum 25-OHD levels were low in about half of the patients and were negatively correlated with age (r = -0.52; p < 0.0001). Patients with NS exhibited reduced bone formation marker levels and increased bone resorption marker levels (p < 0.0001). No gender difference or genotype-phenotype correlations were found for the different bone parameters. Muscle mass and, to a lesser extent, serum insulin-like growth factor 1 (IGF-1) levels were independent predictors of whole-body bone mineral content (p < 0.0001 for both parameters; adjusted R2 = 0.97). In conclusion, bone mass is reduced in children with NS and correlates with decreased muscle mass and low serum IGF-1 levels. These data justify addressing all potential threats to bone health including sufficient calcium and vitamin D intake, regular physical exercise, and hormone replacement therapy.