Lipid profile in Noonan syndrome and related disorders: trend by age, sex and genotype.

Background: RASopathies are developmental disorders caused by dysregulation of the RAS-MAPK signalling pathway, which contributes to the modulation of multiple extracellular signals, including hormones and growth factors regulating energetic metabolism, including lipid synthesis, storage, and degradation. Subjects and methods: We evaluated the body composition and lipid profiles of a single-centre cohort of 93 patients with a molecularly confirmed diagnosis of RASopathy by assessing height, BMI, and total cholesterol, HDL, triglycerides, apolipoprotein, fasting glucose, and insulin levels, in the context of a cross sectional and longitudinal study. We specifically investigated and compared anthropometric and haematochemistry data between the Noonan syndrome (NS) and Mazzanti syndrome (NS/LAH) groups. Results: At the first evaluation (9.5 ± 6.2 years), reduced growth (-1.80 ± 1.07 DS) was associated with a slightly reduced BMI (-0.34 DS ± 1.15 DS). Lipid profiling documented low total cholesterol levels (< 5th percentile) in 42.2% of the NS group; in particular, in 48.9% of PTPN11 patients and in 28.6% of NS/LAH patients compared to the general population, with a significant difference between males and females. A high proportion of patients had HDL levels lower than the 26th percentile, when compared to the age- and sex-matched general population. Triglycerides showed an increasing trend with age only in NS females. Genotype-phenotype correlations were also evident, with particularly reduced total cholesterol in about 50% of patients with PTPN11 mutations with LDL-C and HDL-C tending to decrease during puberty. Similarly, apolipoprotein A1 and apolipoprotein B deficits were documented, with differences in prevalence associated with the genotype for apolipoprotein A1. Fasting glucose levels and HOMA-IR were within the normal range. Conclusion: The present findings document an unfavourable lipid profile in subjects with NS, in particular PTPN11 mutated patients, and NS/LAH. Further studies are required to delineate the dysregulation of lipid metabolism in RASopathies more systematically and confirm the occurrence of previously unappreciated genotype-phenotype correlations involving the metabolic profile of these disorders.

Endocrinological manifestations in RASopathies.

The evaluation of endocrine involvement in RASopathies is important for the care and follow-up of patients affected by these conditions. Short stature is a cardinal feature of RASopathies and correlates with multiple factors. Growth hormone treatment is a therapeutic possibility to improve height and quality of life. Assessment of growth rate and growth laboratory parameters is routine, but age at start of therapy, dose and effects of growth hormone on final height need to be clarified. Puberty disorders and gonadal dysfunction, in particular in males, are other endocrinological areas to evaluate for their effects on growth and development. Thyroid dysfunction, autoimmune disease and bone involvement have also been reported in RASopathies. In this brief review, we describe the current knowledge on growth, growth hormone therapy, endocrinological involvement in patients affected by RASopathies.

Uniparental disomy and pretreatment IGF-1 may predict elevated IGF-1 levels in Prader-Willi patients on GH treatment.

Pediatric patients with Prader-Willi syndrome (PWS) can be treated with recombinant human GH (rhGH). These patients are highly sensitive to rhGH and the standard doses suggested by the international guidelines often result in IGF-1 above the normal range. We aimed to evaluate 1 the proper rhGH dose to optimize auxological outcomes and to avoid potential overtreatment, and 2 which patients are more sensitive to rhGH. In this multicenter real-life study, we recruited 215 patients with PWS older than 1 year, on rhGH at least for 6 months, from Italian Centers for PWS care. We collected auxological parameters, rhGH dose, IGF-1 at recruitment and (when available) at start of treatment. The rhGH dose was 4.3 (0.7/8.4) mg/m2/week. At recruitment, IGF-1 was normal in 72.1% and elevated in 27.9% of the patients. In the group of 115 patients with IGF-1 available at start of rhGH, normal pretreatment IGF-1 and uniparental disomy were associated with elevated IGF-1 during the therapy. No difference in height and growth velocity was found between patients treated with the highest and the lowest range dose. The rhGH dose prescribed in Italy seems lower than the recommended one. Normal pretreatment IGF-1 and uniparental disomy are risk factors for elevated IGF-1. The latter seems to be associated with higher sensitivity to GH. In case of these risk factors, we recommend a more accurate titration of the dose to avoid overtreatment and its potential side effects.

Novel Mutations and Unreported Clinical Features in KBG Syndrome.

KBG syndrome is an autosomal dominant disorder caused by pathogenic variants within ANKRD11 or deletions of 16q24.3 which include ANKRD11. It is characterized by distinctive facial features, developmental delay, short stature, and skeletal anomalies. We report 12 unrelated patients where a clinical diagnosis of KBG was suspected and confirmed by targeted analyses. Nine patients showed a point mutation in ANKRD11 (none of which were previously reported) and 3 carried a 16q24.3 deletion. All patients presented with typical facial features and macrodontia. Skeletal abnormalities were constant, and the majority of patients showed joint stiffness. Three patients required growth hormone treatment with a significant increase of height velocity. Brain malformations were identified in 8 patients. All patients showed behavioral abnormalities and most had developmental delay. Two patients had hematological abnormalities. We emphasize that genetic analysis of ANKRD11 can easily reach a detection rate higher than 50% thanks to clinical phenotyping, although it is known that a subset of ANKRD11-mutated patients show very mild features and will be more easily identified through the implementation of gene panels or exome sequencing. Joint stiffness was reported previously in few patients, but it seems to be a common feature and can be helpful for the diagnosis. Hematological abnormalities could be present and warrant a specific follow-up.

Challenges in the clinical interpretation of small de novo copy number variants in neurodevelopmental disorders.

In clinical genetics, the need to discriminate between benign and pathogenic variants identified in patients with neurodevelopmental disorders is an absolute necessity. Copy number variants (CNVs) of small size can enable the identification of genes that are critical for neurologic development. However, assigning a definite association with a specific disorder is a difficult task. Among 328 trios analyzed over seven years of activity in a single laboratory, we identified 19 unrelated patients (5.8%) who carried a small (<500 kb) de novo CNV. Four patients had an additional independent de novo CNV. Nine had a variant that could be assigned as definitely pathogenic, whereas the remaining CNVs were considered as variants of unknown significance (VUS). We report clinical and molecular findings of patients harboring VUS. We reviewed the medical literature available for genes impacted by CNVs, obtained the probability of truncating loss-of-function intolerance, and compared overlapping CNVs reported in databases. The classification of small non-recurrent CNVs remains difficult but, among our findings, we provide support for a role of SND1 in the susceptibility of autism, describe a new case of the rare 17p13.1 microduplication syndrome, and report an X-linked duplication involving KIF4A and DLG3 as a likely cause of epilepsy.

HDAC8 Loss of Function and SHOX Haploinsufficiency: Two Independent Genetic Defects Responsible for a Complex Phenotype.

We report a patient with developmental delay, brachydactyly type E, short stature, and tetralogy of Fallot. Brachydactyly-mental retardation syndrome (BDMR) was suspected based on the phenotype; however, array CGH excluded a 2q37 deletion, but identified a deletion encompassing the SHOX gene. BDMR is characterized by cognitive impairment, skeletal abnormalities involving hands and feet, short stature, and overweight. Most affected individuals carry relatively large 2q37 deletions encompassing HDAC4. This gene encodes a histone deacetylase involved in epigenetic regulation of cell growth and differentiation, specifically during endochondral bone formation in chondrocyte hypertrophy. Since SHOX haploinsufficiency can cause skeletal defects and short stature but would not fully explain the clinical picture of this patient, exome sequencing was performed, and a heterozygous HDAC8 frameshift mutation was identified. HDAC8 is a distinct histone deacetylase involved in cohesin recycling and is responsible for an X-linked dominant Cornelia de Lange-like phenotype. A new blended clinical phenotype may be explained by the result of a dual molecular diagnosis, which represents a combination of 2 independent genetic defects, with relevant implications for genetic counseling, clinical management, and prognosis.

New insights on diabetes in Turner syndrome: results from an observational study in adulthood.

OBJECTIVE: To explore the characteristics of diabetes mellitus in adults with Turner syndrome. DESIGN: Observational study consisting of a prospective phase after the access of adults with Turner syndrome to the Endocrinology Unit (median period of follow-up 15.6, interquartile range: 12.0-24.5 months) and a retrospective collection of data from the diagnosis of Turner syndrome until the time of access to the Endocrinology Unit. A total of 113 Italian Turner syndrome patients were included in the study. During the prospective phase of the study, each patient underwent physical examination, fasting blood sampling, and an oral glucose tolerance test on a yearly basis. Oral glucose tolerance test was used to perform the diagnosis of diabetes mellitus. RESULTS: Before access to the Endocrinology Unit, diabetes mellitus was diagnosed in two Turner syndrome patients. Another five cases of diabetes mellitus were diagnosed at the first access to the Endocrinology Unit, whereas seven new cases of diabetes mellitus were diagnosed during the prospective phase of the study. At the diagnosis of diabetes mellitus, only one patient had fasting glucose above 126 mg/dL, and only two had an HbA1c value >6.5% (48 mmol/mol). When compared to normo-glucose tolerant patients, the diabetic patients had a significantly lower insulin-to-glucose ratio at 30 and 60 min of the oral glucose tolerance test. In the regression analyses, only age was associated with the development of diabetes mellitus. CONCLUSIONS: This study confirms that diabetes mellitus is frequent in Turner syndrome and suggests that it is specific to the syndrome. In addition, this study demonstrates that oral glucose tolerance test is a more sensitive test than HbA1c for the diagnosis of diabetes mellitus in Turner syndrome.

Response to long-term growth hormone therapy in patients affected by RASopathies and growth hormone deficiency: Patterns of growth, puberty and final height data.

RASopathies are developmental disorders caused by heterozygous germline mutations in genes encoding proteins in the RAS-MAPK signaling pathway. Reduced growth is a common feature. Several studies generated data on growth, final height (FH), and height velocity (HV) after growth hormone (GH) treatment in patients with these disorders, particularly in Noonan syndrome, the most common RASopathy. These studies, however, refer to heterogeneous cohorts in terms of molecular information, GH status, age at start and length of therapy, and GH dosage. This work reports growth data in 88 patients affected by RASopathies with molecularly confirmed diagnosis, together with statistics on body proportions, pubertal pattern, and FH in 33, including 16 treated with GH therapy for proven GH deficiency. Thirty-three patients showed GH deficiency after pharmacological tests, and were GH-treated for an average period of 6.8 ± 4.8 years. Before starting therapy, HV was -2.6 ± 1.3 SDS, and mean basal IGF1 levels were -2.0 ± 1.1 SDS. Long-term GH therapy, starting early during childhood, resulted in a positive height response compared with untreated patients (1.3 SDS in terms of height-gain), normalizing FH for Ranke standards but not for general population and Target Height. Pubertal timing negatively affected pubertal growth spurt and FH, with IGF1 standardized score increased from -2.43 to -0.27 SDS. During GH treatment, no significant change in bone age velocity, body proportions, or cardiovascular function was observed.

GH Therapy and first final height data in Noonan-like syndrome with loose anagen hair (Mazzanti syndrome).

Noonan-like syndrome with loose anagen hair (NS/LAH or Mazzanti Syndrome) is caused by a single missense mutation in SHOC2 promoting tN-myristoylation of the encoded protein. Cardinal features include facial features resembling NS, short stature often associated with proven growth hormone deficiency (GHD), typical ectodermal anomalies, and distinctive behavior. Overall, the clinical features are more severe than those generally observed in NS, even though the phenotype improves with age. We report on growth and pubertal trend in seven patients heterozygous for a mutated SHOC2 allele, treated with long-term GH-therapy, and final height (FH) in three of them. They were approximately -3 SDS below the Italian general population standards, they had very low IGF1 levels at baseline and GHD at pharmacological tests. All patients were treated with GH (0.035 mg/kg/day) for a mean period of 8.49 ± 5.72 years. After the 1st year of GH-therapy, IGF1 level and height velocity had increased. Three of 7 patients reached the FH (-2.34 ± 0.12 SDS) at 18.25 ± 0.73 years, after GH administration for 12.39 ± 2.12 years. Pubertal development was variable, showing a prolonged and delayed puberty or rapid pubertal progression that could impair the FH. Overall, our data in this small cohort suggest that NS/LAH patients benefit from long-term GH-therapy, although they do not show the characteristic catch-up growth of isolated GHD. While the observed growth and pubertal behavior is consistent with a dysfunction of the hypothalamic-pituitary-gonadal axis, the functional link between SHOC2 and the GH/IGF signaling pathways remains to be clarified.

Turner syndrome strategies to improve care outcomes--cardiac evaluation using new imaging techniques.

Turner syndrome (TS) is at high risk for congenital heart diseases (CHD), aortic dilatation (AoDil) and dissection. New imaging techniques such as MRI have revealed the presence of vascular anomalies (VA) undetected at echo. MR angiography has shown a high prevalence of aortic and venous anomalies. The VA often coexist and interact to increase the risk of premature death in adulthood. AoDil and VA have been found also in asymptomatic individuals with no predisposing factors, but the prevalence is still unknown. We evaluated 100 TS subjects (15-35 yrs) with no aortic CHD at echocardiography with transthoracic MRA; 42 of them showed VA and 58 did not. Aortic diameters were indexed on BSA. At the sinuses of Valsalva a higher prevalence of AoDil was found in subjects with VA than without; 57% of them showed AoDil. The presence of VA (elongation of the transverse arch, bovine arch, left superior vena cava, PAPVD etc.) increased their relative risk of AoDil by more than 2 times. Excluding BSA influence, a severe phenotype influenced positively ascending AoDil. New imaging techniques enhance our ability to provide a prognosis for their adult age and in particular before they seek to become pregnant.