Growth and Growth Hormone Treatment in Noonan Syndrome.

Short stature is a common characteristic of Noonan Syndrome (NS), a genetic condition caused by mutations affecting the RAS / mitogen-activated protein kinase (MAPK) cascade. Growth hormone (GH) has been used to normalize childhood growth and increase adult height in NS. GH is effective in increasing growth velocity, and significantly improves height SDS at adult height. Studies of GH treatment to adult height have shown height gains of 9.5-13.0 cm for males and 9.0 - 9.8 cm for females. Factors associated with improved height outcomes are earlier initiation of therapy, a greater height SDS at pubertal onset, and a longer duration of GH therapy. The safety data to date is reassuring and includes no evidence of adverse cardiac effects or increased occurrence of malignancies. Further studies will likely clarify the role of different RAS/MAPK pathway aberrations in growth and GH responsiveness. Continued surveillance is needed to assure the long term safety of GH therapy.

National Cooperative Growth Study: 25 Years of Growth Hormone Data, Insights, and Lessons for Future Registries.

BACKGROUND: The National Cooperative Growth Study (NCGS) data are reviewed from 1985-2010 to report on final demographic, efficacy, and safety findings, and to illustrate the value of long-term, real-world follow-up to physicians and patients. METHODS: The NCGS was a multicenter, open-label, observational, postmarketing surveillance study of Genentech growth hormone (GH) products for the treatment of children with growth failure in North America. FINDINGS: Data from 65,205 patients representing 240,951 patient-years of experience were collected. All etiological groups had clinically meaningful improvements in near-adult height SDS. Females and African Americans were under-represented in the NCGS with little change in accrual over time. The favorable safety profile of GH was validated through the registry. CONCLUSIONS: Twenty-five years of monitoring GH use through the NCGS yielded extensive insight into the utility of GH in various underlying etiologies. Demographic disparities were clear and became evident by analyzing data collected through the registry.

Evaluation of bleeding disorders in patients with Noonan syndrome: a systematic review.

BACKGROUND: Noonan syndrome (NS) is an autosomal dominant genetic condition that has a number of clinical features, including bleeding diathesis and a number of hematological abnormalities including clotting factor deficiencies, von Willebrand disease and abnormal platelet count/function. METHODS: We evaluated the frequency/types of bleeding disorders, and associated hematological laboratory findings, in patients with NS, using published data from 1965 to 2014. RESULTS: Of 45 studies identified, 31 included data for 428 patients with NS. Of these patients, 43% had reported bleeding, 26% had no reported bleeding and no bleed data was reported for 31%. Most patients (90%) had bleeding-related laboratory test abnormalities, but only 194 (45%) had a confirmed diagnosis of a specific bleeding disorder. Abnormal laboratory tests included: prolonged prothrombin time, activated partial thromboplastin time, and other platelet-related disorders. Of the 194 patients with a confirmed diagnosis of a specific bleeding disorder, 153 (79%) had single clotting factor deficiencies, von Willebrand disease or platelet-related disorders, and 41 (21%) had multiple deficiencies including platelet-related disorders. CONCLUSION: As patients with NS can experience multiple bleeding disorders, including abnormal platelet function, clinical evaluations should be performed at diagnosis, after diagnosis, before any surgery is undertaken, and if patients become symptomatic.

Noonan syndrome: clinical features, diagnosis, and management guidelines.

Noonan syndrome (NS) is a common, clinically and genetically heterogeneous condition characterized by distinctive facial features, short stature, chest deformity, congenital heart disease, and other comorbidities. Gene mutations identified in individuals with the NS phenotype are involved in the Ras/MAPK (mitogen-activated protein kinase) signal transduction pathway and currently explain ∼61% of NS cases. Thus, NS frequently remains a clinical diagnosis. Because of the variability in presentation and the need for multidisciplinary care, it is essential that the condition be identified and managed comprehensively. The Noonan Syndrome Support Group (NSSG) is a nonprofit organization committed to providing support, current information, and understanding to those affected by NS. The NSSG convened a conference of health care providers, all involved in various aspects of NS, to develop these guidelines for use by pediatricians in the diagnosis and management of individuals with NS and to provide updated genetic findings.

Growth response, near-adult height, and patterns of growth and puberty in patients with noonan syndrome treated with growth hormone.

CONTEXT: Noonan syndrome (NS) is a heterogeneous genetic disorder characterized by short stature. SETTING: The National Cooperative Growth Study (NCGS), a postmarketing observational study of recombinant human GH (rhGH)-treated children, includes a large cohort of children with NS. PATIENTS: We studied NCGS-enrolled prepubertal and pubertal children with NS. MAIN OUTCOMES: Baseline characteristics and growth responses in NS patients with reported near-adult height (NAH) (n = 65) were compared to patients with idiopathic GH deficiency (n = 3007) and Turner syndrome (TS; n = 1378) with reported NAH to identify factors contributing to NAH optimization in NS. RESULTS: NS patients (mean enrollment age, 11.6 yr) received rhGH (mean, 0.33 mg/kg . wk) for a mean of 5.6 yr. No significant difference was observed in Delta height sd score (SDS) between NS (+1.4 +/- 0.7) and TS (+1.2 +/- 0.9). However, Delta height SDS for NS and TS differed significantly from idiopathic GH deficiency (+1.7 +/- 1.0) (P < 0.0001). Mean gain in NAH above projected was 10.9 +/- 4.9 cm (males) and 9.2 +/- 4.0 cm (females). Duration of prepubertal rhGH was an important contributor to prepubertal change in height SDS (r(2) = 0.97). Height SDS at pubertal onset highly correlated with NAH SDS (rho = 0.783; P < 0.0001). Duration of puberty highly correlated with pubertal height gain in centimeters for males (rho = 0.941) and females (rho = 0.882) (P < 0.01). No new adverse events were observed. CONCLUSIONS: rhGH significantly improved height SDS for children with NS at NAH. Duration of prepubertal rhGH and height SDS at puberty were important contributors to NAH. Because starting age of the patients in this report was 11.6 yr, these data suggest that greater growth optimization is possible with earlier initiation of therapy.