Federica Tamburrino

Loss-of-function variants of SETD5 cause intellectual disability and the core phenotype of microdeletion 3p25.3 syndrome

Intellectual disability (ID) has an estimated prevalence of 2–3%. Due to its extreme heterogeneity, the genetic basis of ID remains elusive in many cases. Recently, whole exome sequencing (WES) studies revealed that a large proportion of sporadic cases are caused by de novo gene variants. To identify further genes involved in ID, we performed WES in 250 patients with unexplained ID and their unaffected parents and included exomes of 51 previously sequenced child–parents trios in the analysis. Exome analysis revealed de novo intragenic variants in SET domain-containing 5 (SETD5) in two patients. One patient carried a nonsense variant, and the other an 81 bp deletion located across a splice-donor site. Chromosomal microarray diagnostics further identified four de novo non-recurrent microdeletions encompassing SETD5. CRISPR/Cas9 mutation modelling of the two intragenic variants demonstrated nonsense-mediated decay of the resulting transcripts, pointing to a loss-of-function (LoF) and haploinsufficiency as the common disease-causing mechanism of intragenic SETD5 sequence variants and SETD5-containing microdeletions. In silico domain prediction of SETD5, a predicted SET domain-containing histone methyltransferase (HMT), substantiated the presence of a SET domain and identified a novel putative PHD domain, strengthening a functional link to well-known histone-modifying ID genes. All six patients presented with ID and certain facial dysmorphisms, suggesting that SETD5 sequence variants contribute substantially to the microdeletion 3p25.3 phenotype. The present report of two SETD5 LoF variants in 301 patients demonstrates a prevalence of 0.7% and thus SETD5 variants as a relatively frequent cause of ID.

From Whole Gene Deletion to Point Mutations of EP300‐Positive Rubinstein–Taybi Patients: New Insights into the Mutational Spectrum and Peculiar Clinical Hallmarks

Rubinstein–Taybi syndrome (RSTS) is a rare congenital neurodevelopmental disorder characterized by growth deficiency, skeletal abnormalities, dysmorphic features, and intellectual disability. Causative mutations in CREBBP and EP300 genes have been identified in ∼55% and ∼8% of affected individuals. To date, only 28 EP300 alterations in 29 RSTS clinically described patients have been reported. EP300 analysis of 22 CREBBP‐negative RSTS patients from our cohort led us to identify six novel mutations: a 376‐kb deletion depleting EP300 gene; an exons 17–19 deletion (c.(3141+1_3142‐1)_(3590+1_3591‐1)del/p.(Ile1047Serfs*30)); two stop mutations, (c.3829A>T/p.(Lys1277*) and c.4585C>T/p.(Arg1529*)); a splicing mutation (c.1878‐12A>G/p.(Ala627Glnfs*11)), and a duplication (c.4640dupA/p.(Asn1547Lysfs*3)). All EP300‐mutated individuals show a mild RSTS phenotype and peculiar findings including maternal gestosis, skin manifestation, especially nevi or keloids, back malformations, and a behavior predisposing to anxiety. Furthermore, the patient carrying the complete EP300 deletion does not show a markedly severe clinical picture, even if a more composite phenotype was noticed. By characterizing six novel EP300‐mutated patients, this study provides further insights into the EP300‐specific clinical presentation and expands the mutational repertoire including the first case of a whole gene deletion. These new data will enhance EP300‐mutated cases identification highlighting distinctive features and will improve the clinical practice allowing a better genotype–phenotype correlation.

Developmental syndromes: growth hormone deficiency and treatment.

Developmental syndromes are characterized by numerous phenotypical signs and malformations. In most of them such as Turner, Noonan, Prader-Willi, Silver-Russel, Williams, Kabuki, Leri-Weill syndrome and skeletal dysplasias, short stature is a common feature. Growth defect is very often related to a defect in cellular growth, but some unknown abnormality in GH action is possible. Recently, the greater availability of recombinant GH has expanded the interest towards GH secretion and therapy also in developmental syndromes. We recognize syndromes associated with GH deficiency (GHD), showing a developmental midline defect such as Pallister-Hall syndrome, septo-optic dysplasia, but many of these conditions do not have a convincing link with GHD. Moreover, some conditions, in particular the well-studied Turner syndrome, that do not have a real GHD, have proven to benefit from GH therapy at supra-physiological doses obtaining a higher final height than the expected one according to the natural history. This has expanded the indications for GH therapy. The aim of our paper is to review the literature on GH secretion, on the effects and costs-benefits of GH therapy in many dysmorphic syndromes, presenting some results of GH secretion and therapy obtained in our experience.

Correlations of phenotype and genotype in relation to morphologic remodelling of the aortic root in patients with Turner’s syndrome

BACKGROUND Patients with Turners syndrome are at risk of aortic dilation and dissection. Currently, it is not known whether such dilation is related to associated cardiovascular abnormalities, or to the genetic anomaly itself. METHODS We studied echocardiographically 107 patients with genetically proven Turners syndrome, with heterogeneous underlying karyotypes, and without associated cardiac lesions. Their average age was 19.6 plus or minus 8.4 years. We compared the finding with those from 71 age-matched healthy female volunteers. The diameter of the aorta was measured at the level of the basal attachments of the aortic valvar leaflets, the sinuses of Valsalva, the sinutubular junction, and its ascending component. RESULTS Compared to control subjects, the patients with Turners syndrome had larger diameters of the aorta at the level of the sinuses of Valsalva, at 23.4+/-4.8 versus 25.5+/-4.1 millimetres (p = 0.0014), the sinutubular junction, at 19.9+/-3.8 versus 23.3+/-4.1 millimetres (p < 0.0001), and the ascending aorta, at 22.3+/-4.9 versus 24.6+/-4.4 millimetres (p = 0.0011). Dilation of the sinutubular junction, found in just over one-quarter of the patients, was more common than dilation of the ascending aorta, the latter found in less than one-tenth. The patients with Turners syndrome, therefore, presented with remodelling of the aortic root, with relative dilation of the sinutubular junction. The underlying karyotype influenced both the dimensions of the sinutubular junction (p = 0.0054), and the ascending aorta (p = 0.0064), so that patients with the karyotype 45X had larger aortas. The karyotype was the strongest predictor by multivariate analysis for dilation at both these sites (p = 0.0138 and 0.0085, respectively). CONCLUSIONS Dilation at the sinutubular junction is frequent in patients with Turners syndrome, and is more common than dilation of the ascending aorta. The syndrome is associated with a remodelling of the aortic root, with prominent dilation of the sinutubular junction. There seems to be a relation between aortic dilation and the underlying genotype.

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.

The Influence of Growth Hormone Treatment on Glucose Homeostasis in GrowthHormone-Deficient Children: A Six-Year Follow-Up Study

Background: Growth hormone (GH) influences glucose homeostasis by negatively affecting insulin sensitivity, leading to a compensatory increase in insulin secretion. It has recently been reported, in animals and humans, that GH might also stimulate insulin secretion by directly affecting the growth and function of pancreatic β-cells. The aim of this work was to longitudinally study the insulin sensitivity (HOMA-S), insulin secretion [insulinogenic index (IGI)] and capacity of β-cells to adapt to changes in insulin sensitivity [oral disposition index (ODI)] in GH-deficient (GHD) children under GH treatment. Methods: We studied 99 GHD (62 male, 37 female; age 8.9 ± 3.5 years) children for a median period of 6 years (range 1.5-16.2). Every year, our patients underwent an oral glucose tolerance test, which was used to calculate the HOMA-S, IGI and ODI. Results: Although HOMA-S remained unchanged, an increase in IGI and ODI was observed, becoming significant after 6 years of treatment (1.25 ± 1.28 vs. 2.35 ± 2.38, p < 0.05 and 0.57 ± 0.68 vs. 1.50 ± 1.92, p < 0.01, respectively). Conclusion: Our results suggest a positive influence of GH treatment on the β-cell secretory capacity in children with GH deficiency.

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.

The influence of GH treatment on glucose homeostasis in girls with Turner Syndrome: a 7 years study

Context Growth hormone (GH) influences glucose homeostasis mainly by negatively affecting insulin sensitivity. Objective To longitudinally study insulin sensitivity [via homeostasis model assessment of insulin sensitivity (HOMA-S)], insulin secretion [insulinogenic index (IGI)], and capacity of β cells to adapt to changes in insulin sensitivity [oral disposition index (ODI)] in girls with Turner syndrome (TS) undergoing GH treatment. Design and Setting Longitudinal, retrospective, 7-year study conducted in a tertiary pediatric endocrine unit and university pediatric clinic. Patients and Methods We studied 104 patients with TS (mean age ± standard deviation, 9.1 ± 3.4 years) for a median of 7.2 years. Intervention Every year, the children underwent an oral glucose tolerance test, which was used to calculate HOMA-S, IGI, and ODI. Results HOMA-S, IGI, and ODI did not significantly change. Conclusion The results are reassuring, showing no negative influence of GH treatment on insulin sensitivity and on β-cell secretory capacity in girls with TS.

Neuropsychiatric phenotype in a child with pseudohypoparathyroidism

Pseudohypoparathyroidism (PHP) is a rare heterogeneous genetic disease characterized by end-organ resistance to parathyroid hormone. In adulthood, heterogeneous neurological and psychiatric disorders have been reported which are associated with hypoparathyroidism in general and with PHP in particular, while for childhood, data are scanty. We report a case of a boy with PHP type 1b, in whom neurological signs at the onset prevailed, characterized by tic-like dyskinesias associated with a series of heterogeneous not well-defined neurological and behavioral features, describing the diagnostic work-up performed and the follow-up. We suggest that the diagnostic hypothesis of PHP might be considered when dealing with a child with tic-like dyskinesias, especially if associated with a series of heterogeneous not well-defined neurological and behavioral features. In these cases, treatment with calcitriol and calcium has to be started as soon as possible to achieve a prompt and persistent clinical improvement.