Etiology and treatment of growth delay in noonan syndrome

Noonan syndrome is characterized by multiple phenotypic features, including growth retardation, which represents the main cause of consultation to the clinician. Longitudinal growth during childhood and adolescence depends on several factors, among them an intact somatotrophic axis, which is characterized by an adequate growth hormone (GH) secretion by the pituitary, subsequent binding to its receptor, proper function of the post-receptor signaling pathway for this hormone (JAK-STAT5b and RAS/MAPK), and ultimately by the production of its main effector, insulin like growth factor 1 (IGF-1). Several studies regarding the function of the somatotrophic axis in patients with Noonan syndrome and data from murine models, suggest that partial GH insensitivity at a post-receptor level, as well as possible derangements in the RAS/MAPK pathway, are the most likely causes for the growth failure in these patients. Treatment with recombinant human growth hormone (rhGH) has been used extensively to promote linear growth in these patients. Numerous treatment protocols have been employed so far, but the published studies are quite heterogeneous regarding patient selection, length of treatment, and dose of rhGH utilized, so the true benefit of GH therapy is somewhat difficult to establish. This review will discuss the possible etiologies for the growth delay, as well as the outcomes following rhGH treatment in patients with Noonan syndrome

Sweet lupin protein quality in young men

The protein quality of Lupinus albus cv Multolupa was evaluated in young adult males using the nitrogen balance technique at graded levels of N intake, and compared with egg protein. Lupin protein was consumed at levels of 0.4, 0.6 and 0.8 g/(kg · d) and egg protein at 0.3, 0.45 and 0.6 g/(kg · d). Each period started with 1 d of consuming a protein-free diet; the next 6 d were used as adaptation and the last 4 d for balance. The levels of protein intake were randomly assigned by a modified Latin square. Energy intake was individually adjusted. Mean apparent N digestibility values of lupin protein were 78.8, 76.1 and 70.2% for the levels of 0.8, 0.6 and 0.4 g protein(kg · d), respectively, and 83.8, 78.3 and 67.1% for egg protein consumed at levels of 0.6, 0.45 and 0.3 g protein/(kg · d), respectively. The N balance results obtained when subjects consumed lupin were 16.4, 0.2 and -15.1 mg N/(kg · d) for protein intakes of 0.8, 0.6 and 0.4 g/(kg · d), respectively. Those obtained for e

Molecular characterization of Chilean patients with a clinical diagnosis of Noonan syndrome

Artículo de publicación ISIBackground: Noonan syndrome (NS) is an autosomal dominant syndrome characterized by typical dysmorphic features, cardiac anomalies as well as postnatal growth retardation, and is associated with Ras-MAPK pathway gene mutations. The purpose of this study was to improve the diagnosis of Chilean patients with suspected NS through molecular analysis. Methods: We screened 18 Chilean patients with a clinical diagnosis of NS for mutations in PTPN11 by high resolution melting (HRM) and subsequent sequencing. Results: Three PTPN11 missense mutations were detected in 22% of analyzed patients. Of these, two (c.181G > A and c.1510A > G) were previously reported and one was the novel substitution c.328G > A (p.E110K) affecting the linker stretch between the N-SH2 and C-SH2 domains of SHP-2 protein. Conclusion: Molecular studies confirmed the clinical diagnosis of NS in 4 of 18 patients, which provided support for therapeutic decisions and improved genetic counseling for their families

Age of menarche and its relationship with body mass index and socioeconomic status

Artículo de publicación ISIBackground: A decline in the age of menarche was observed from early 1900s to the 1970s. However, it is not known if a further decline ocurred thereafter. Aim: To evaluate the age of menarche in girls from Santiago, Chile and its relationship with body mass index (BMI) and socioeconomic status. Material and Methods: We studied 1302 healthy girls aged 7 to 19 years. Age of menarche was evaluated through a questionnaire to the patient and her parents. Kaplan-Meier curves were used to determine age of menarche and Cox regression analysis was employed to evaluate the effect of the type of school and BMI on the age of menarche. Results: The mean age at menarche was 12.7±0.04 years. Girls from public and private schools had their period at 12.5±0.1 and 13.05±0.05 years respectively. A negative correlation between z scores for BMI and age of menarche was observed (r-0.3: p =0.001). Girls whose menarche occurred before 11.5 years had higher z scores for BMI and a larger proportion were overweight, compared to girls who had menarche later. Cox regression analysis showed that after adjusment for BMI, age of menarche was similar in both types of schools. Conclusions: Age of menarche is ocurring three months earlier in girls from public schools, which is associated with higher z scores for BMI. Type of school, a marker of socio-economic status in Chile, affects timing of menarche due to differences in body mass index

Developmental changes and differential regulation by testosterone and estradiol of growth hormone receptor expression in the rabbit

To investigate the effects of testosterone and estradiol (E2) on growth hormone receptor (GH-R) gene expression, we measured GH-R mRNA levels in relation to the changes of sex steroid concentrations in the normal male rabbits aged 1-12 months and after administration of testosterone or E2 to castrated male rabbits. In the normal animals. E2 levels were below the detection limit in all age groups, and testosterone levels were below the detection limit at 1 month, increased at 2 months and reached the plateau of the adult levels after 4 months. Liver GH-R mRNA levels were low at 1 month, reached a peak at 2 months and then decreased slightly thereafter. In the castrated animals, liver and growth plate GH-R mRNA levels were increased in the testosterone-treated group (162.0 ± 12.0%, p <0.025; 128.4 ± 7.6%; p< 0.025) and reduced in the E2-treated group (29.6 ± 6.2%, p < 0.005; 53.6 ± 11.3%, p < 0.025). Sex steroid administration did not result in any significant change in GH-R mRNA level

Clinical and molecular characterization of Chilean patients with Léri-Weill dyschondrosteosis

Artículo de publicación ISIAim: L é ri-Weill dyschondrosteosis (LWD) is a mesomelic dysplasia with disproportionate short stature associated with short stature homeobox-containing gene (SHOX) haploinsufficiency. The objective of this study was to improve the diagnosis of patients with suspected LWD through molecular analysis. Methods: Twelve patients from 11 families with a clinical diagnosis of LWD were analyzed with multiplex ligationdependent probe amplification to detect deletions and duplications of SHOX and its enhancer regions. High resolution melting and sequencing was employed to screen for mutations in SHOX coding exons. Results: The molecular-based screening strategy applied in these patients allowed detection of five SHOX deletions and two previously unreported SHOX missense mutations. Conclusion: Molecular studies confirmed the clinical diagnosis of LWD in seven out of 12 patients, which provided support for therapeutic decisions and improved genetic counseling in their families

Co-occurrence of Noonan and Cardio-facio-cutaneous syndrome features in a patient with KRAS variant

We report the case of a 3-year-old girl, who is the third child of nonconsanguineous parents with short stature, hypertrophic cardiomyopathy and mild dysmorphic features; all suggestive of Noonan syndrome. In addition, the patient presents with feeding difficulties, deep palmar and plantar creases, sparse hair, and delayed psychomotor and language development, all characteristics frequently observed in Cardio-facio-cutaneous syndrome. Molecular analysis of the Ras/MAPK pathway genes using high resolution melting curve analysis and gene sequencing revealed a de novo KRAS amino acid substitution of leucine to tryptophan at codon 53 (p.L53W). This substitution was recently described in an Iranian patient with Noonan syndrome. The findings described in the present report expand the phenotypic heterogeneity observed in RASopathy patients harbouring a KRAS substitution, and advocate for the inclusion of genes with low mutational frequency in genetic screening protocols for Noonan syndrome and other RASophaties

Effects of the IGF-I/IGFBP-3 complex on GH and ghrelin nocturnal concentrations in low birth weight children

Objective There is limited information regarding the effects of IGF-I and/or IGFBP-3 on circulating ghrelin concentrations. To determine the effects of IGF-I on GH and ghrelin concentrations, we examined the GH and ghrelin nocturnal profiles before and after the administration of the IGF-I/-IGFBP-3 complex (Iplex (TM)) to low birth weight children. Design The children were studied on two separate occasions, the first under basal conditions, and the second time after the sc administration of 1 mg/kg of Iplex (TM) at 2100 h. Blood samples for determination of GH and ghrelin were obtained every 20 min between 2300 h and 0700 h, while the children were sleeping. In each patient, we calculated the mean GH and ghrelin area under the curve (GH AUC and GHR AUC), both under basal conditions and after the administration of the IGF-I/IGFBP-3 complex. Setting The study was performed at a University Research Centre located at a General Hospital in Santiago, Chile. Patients Twenty prepubertal children (11 boys and 9 girls), born after a full-term pregnancy with a birth weight below 2.8 kg were studied at a mean +/- SEM age of 7.3 +/- 0.5 years (range 4-11 years). Their mean height was -1.8 +/- 0.3 standard deviation score (SDS) and their mean BMI was 0.1 +/- 0.2 SDS at the time of the study. Main outcome and results Mean nocturnal GH AUC exhibited a significant decrease (2903 +/- 185 vs 1860 +/- 122 ng/ml min, P < 0.01), whereas mean GHR AUC showed a significant increase after administration of the IGF-I/IGFBP-3 complex (68 +/- 16 vs 288 +/- 36 ng/ml min, P < 0.01). Conclusions These findings indicate that the IGF-I/IGFBP-3 complex appears to have opposite effects on circulating GH and ghrelin concentrations in low birth weight children, suggesting that, in addition to its known negative feed-back effect on GH, IGF-I and/or IGFBP-3 may have a positive feed-back effect on ghrelin

Anti-Mullerian hormone levels in peripubertal daughters of women with polycystic ovary syndrome

Context: We have previously observed increased anti-Mullerian hormone (AMH) levels in prepubertal daughters of polycystic ovary syndrome (PCOS) women, suggesting that these girls may have an altered follicular development. However, it is not known whether AMH levels remain increased during puberty. Objective: The aim was to establish whether the increased AMH levels observed in prepubertal daughters of PCOS women persist during the peripubertal period, a stage during which the gonadal axis is activated and PCOS may become clinically manifested. Design: We studied 28 daughters (8-16 yr old) of PCOS women (PCOSd) and 33 daughters (8-16 yr old) of control women (Cd). In both groups, an oral glucose tolerance test was performed. Gonadotropins, sex hormones, and AMH were determined in a fasting sample. Results: Both groups were comparable in age, body mass index, and breast Tanner stage. Free androgen index, testosterone, AMH ( Cd 14.4 +/- 8.0 pM vs. PCOSd 24.0 +/- 19.0 pM; P = 0.012), and 2-h insulin levels were significantly higher in the PCOSd group compared with the control group. The average ovarian volume was significantly higher in the PCOSd group. In both groups a positive correlation between 2-h insulin and AMH concentrations was observed (PCOSd: r = 0.530, P = 0.007; Cd: r = 0.561, P = 0.008). Conclusions: AMH concentrations are increased in peripubertal PCOSd. These findings, along with the results of our previous study, suggest that PCOSd appear to show an increased follicular mass that is established during early development, and persists during puberty.This work was supported by Fondo Nacional del Desarrollo Científico y Tecnológico Grant 1030487 and by the Alexander von Humboldt Foundatio