Noonan syndrome patients beyond the obvious phenotype: A potential unfavorable metabolic profile.

Noonan syndrome (NS) and NS related disorders (NRD) are frequent monogenic diseases. Pathogenic variants in PTPN11 are observed in approximately 50% of these NS patients. Several pleiotropic phenotypes have previously been described in this condition. This study aimed at characterizing glucose and lipid profiles in patients with NS/NRD. We assessed fasting blood glucose, insulin, cholesterol (total and fractions), and triglyceride (TG) levels in 112 prepubertal children and 73 adults. Additionally, an oral glucose tolerance test (OGTT) was performed in 40 children and 54 adults. Data were analyzed between age groups according to the presence (+) or absence (-) of PTPN11 mutation. Prepubertal patients with NS/NRD were also compared with a control group. Despite the lean phenotype of children with NS/NRD, they presented an increased frequency of low HDL-cholesterol (63% in PTPN11+, 59% in PTPN11- and 16% in control, p < .001) and high TG levels (29% in PTPN11+, 18% in PTPN11- and 2.3% in control). PTPN11+ patients had a higher median HOMA-IR (1.0, ranged from 0.3 to 3.2) in comparison with PTPN11- (0.6; 0.2 to 4.4) and controls (0.6; 0.4 to 1.4, p = .027). Impaired glucose tolerance was observed in 19% (10:54) of lean adults with NS/NRD assessed by OGTT. Moreover, women with PTPN11 mutations had lower HDL-cholesterol levels than those without. Our results suggest that children and young adult patients with NS/NRD have an unfavorable metabolic profile characterized by low HDL, a tendency of elevated TGs, and glucose metabolism impairment despite a lean phenotype.

Growth and Clinical Characteristics of Children with Floating-Harbor Syndrome: Analysis of Current Original Data and a Review of the Literature.

BACKGROUND: Floating-Harbor syndrome (FHS) is a rare condition characterized by dysmorphic facial features, short stature, and expressive language delay. OBJECTIVE: The aim of this study was to describe a cohort of patients with FHS and review the literature about the response to recombinant human growth hormone (rhGH) therapy. METHODS: Anthropometric and laboratory data from 7 patients with FHS were described. The molecular diagnosis was established by multigene analysis. Moreover, we reviewed the literature concerning patients with FHS treated with rhGH. RESULTS: All 7 patients were born small for gestational age. At first evaluation, 6 patients had a height standard deviation score (SDS) ≤-2 and 1 had short stature in relation to their target height. Bone age was usually delayed, which rapidly advanced during puberty. Nonspecific skeletal abnormalities were frequently noticed, and normal to elevated plasma IGF-I levels were observed in all except 1 patient with growth hormone deficiency. Information about 20 patients with FHS treated with rhGH was analyzed (4 from our cohort and 16 from the literature). The median height changes during the treatment period (approx. 2.9 years) were 1.1 SDS (range from -0.4 to 3.1). Nontreated patients had an adult height SDS of -4.1 ± 1.2 (n = 10) versus -2.6 ± 0.8 SDS (n = 7, p 0.012) for treated patients. CONCLUSION: We observed a laboratory profile compatible with IGF-1 insensitivity in some patients with FHS. Nevertheless, our study suggests that children with FHS may be considered as candidates for rhGH therapy. Further studies are necessary to establish the real benefit and safety of rhGH therapy in these patients.

Novel SUZ12 mutations in Weaver-like syndrome.

SUZ12 is a core component of polycomb repressive complex 2 (PRC2) along with EZH2 and EED. Recently, germline mutations in the SUZ12, EZH2 and EED genes have been reported in Weaver syndrome (WS) or Weaver-like syndrome, suggesting a functional link between PRC2 deficits and WS. However, only one case of a SUZ12 mutation presenting with Weaver-like syndrome has been reported. Here, we report a missense and a frameshift mutation in SUZ12 (c.1797A>C; p.Gln599His and c.844_845del; p.Ala282Glnfs*7), both of which are novel, in two individuals. Their clinical features included postnatal overgrowth, increased bifrontal diameter, large ears, round face, horizontal chin crease and skeletal anomalies, but did not fulfill the WS diagnostic criteria. These data provide strong evidence that SUZ12 mutations cause Weaver-like syndrome.

MANAGEMENT OF ENDOCRINE DISEASE: Diagnostic and therapeutic approach of tall stature.

Tall stature is defined as a height of more than 2 standard deviations (s.d.) above average for same sex and age. Tall individuals are usually referred to endocrinologists so that hormonal disorders leading to abnormal growth are excluded. However, the majority of these patients have familial tall stature or constitutional advance of growth (generally associated with obesity), both of which are diagnoses of exclusion. It is necessary to have familiarity with a large number of rarer overgrowth syndromes, especially because some of them may have severe complications such as aortic aneurysm, thromboembolism and tumor predisposition and demand-specific follow-up approaches. Additionally, endocrine disorders associated with tall stature have specific treatments and for this reason their recognition is mandatory. With this review, we intend to provide an up-to-date summary of the genetic conditions associated with overgrowth to emphasize a practical diagnostic approach of patients with tall stature and to discuss the limitations of current growth interruption treatment options.