Noonan syndrome: comparing mutation-positive with mutation-negative dutch patients.

Noonan syndrome (NS) is an autosomal dominant disorder characterized by facial dysmorphisms, short stature and congenital heart defects. The disorder is genetically heterogeneous and shows clinical overlap with other RASopathies. These syndromes are caused by mutations in a variety of genes leading to dysregulation of the RAS-MAPK pathway: PTPN11, KRAS, SOS1, RAF1, CBL, SHOC2, NRAS, BRAF, MAP2K1, MAP2K2, HRAS, NF1 and SPRED1. In this study, we conduct a genotype-phenotype analysis of 33 patients with a clinical diagnosis of NS without a PTPN11 mutation. Mutation analysis of the genes involved in RASopathies was performed, except for NF1 and SPRED1. In 14 (42%) NS patients, a mutation was found, 7 (21%) had a mutation in SOS1, 3 (9%) in RAF1 and 1 (3%) in KRAS, MAP2K2, BRAF and SHOC2 each. The phenotype of these mutation-positive cases corresponded to that described in the literature. In the cases with a BRAF and MAP2K2 mutation, the diagnosis cardio-facio-cutaneous syndrome was made. The patient with the SHOC2 mutation had features compatible with 'Noonan-like syndrome with loose anagen hair'. Three major clinical features of NS - a typical face, short stature and a pulmonary valve stenosis - were less frequently present in the group without a mutation. Missense mutations in genes encoding proteins of the RAS-MAPK pathway cause NS. The 3 major clinical features of NS were less frequently present in the mutation-negative patients, which stresses the importance of the syndrome-specific symptoms of the face, heart and short stature in NS. However, all mutation-negative cases met the NS criteria, indicating that the involvement of novel genes is to be expected.

Are ECG abnormalities in Noonan syndrome characteristic for the syndrome?

Of all patients with Noonan syndrome, 50-90% have one or more congenital heart defects. The most frequent occurring are pulmonary stenosis (PS) and hypertrophic cardiomyopathy. The electrocardiogram (ECG) of a patient with Noonan syndrome often shows a characteristic pattern, with a left axis deviation, abnormal R/S ratio over the left precordium, and an abnormal Q wave. The objective of this study was to determine if these ECG characteristics are an independent feature of the Noonan syndrome or if they are related to the congenital heart defect. A cohort study was performed with 118 patients from two university hospitals in the United States and in The Netherlands. All patients were diagnosed with definite Noonan syndrome and had had an ECG and echocardiography. Sixty-nine patients (58%) had characteristic abnormalities of the ECG. In the patient group without a cardiac defect (n = 21), ten patients had a characteristic ECG abnormality. There was no statistical relationship between the presence of a characteristic ECG abnormality and the presence of a cardiac defect (p = 0.33). Patients with hypertrophic cardiomyopathy had more ECG abnormalities in total (p = 0.05), without correlation with a specific ECG abnormality. We conclude that the ECG features in patients with Noonan syndrome are characteristic for the syndrome and are not related to a specific cardiac defect. An ECG is very useful in the diagnosis of Noonan syndrome; every child with a Noonan phenotype should have an ECG and echocardiogram for evaluation.

Vermindering van diagnostiek en overbehandeling bij RS-virus-bronchiolitis na geprotocolleerde behandeling.

PURPOSE: Evaluating the guideline 'Diagnosis and treatment of respiratory syncytial (RS) virus bronchiolitis' on the number of chest X-rays, C-reactive proteïn (CRP) counts, leukocyte counts, and antibiotic prescriptions in infants admitted to hospital with RS bronchiolitis. DESIGN: Retrospective 'before-after' cohort study. LOCATION: Canisius-Wilhelmina Hospital, Nijmegen, The Netherlands. PATIENTS: Infants admitted with proven RS virus infection. METHODS: Guidelines, including sound restriction of performance of X-rays, CRP and leukocytes, were introduced in February 2003. Data from infants admitted with RS virus infection during 1997- 1999 (cohort A) were compared with those admitted from 2003- April 2006 (cohort B)Results: There were 155 infants in cohort A and 170 in cohort B. Implementation of guidelines led to significant reductions of CRP and leukocyte determinations: 49.0% and 48.2%, respectively (both p<0.001) and X-rays: 30.3% (p=0.020). Numbers of antibiotic prescriptions decreased with 55% (p<0.001). The chance of antibiotic prescription increased significantly when X-rays (OR=5.2), CRP (OR=5.4), or leukocytes (OR=4.2) were done. After implementation of the guidelines, the median stay in hospital decreased significantly from 8.0 to 6.0 days (p<0.001; ranges 1-13 days and 2-23 days, respectively). Performing X-ray, CRP or leukocytes, or antibiotic prescription did not significantly alter the total duration of hospital stay. CONCLUSION: Implementation of the guidelines led to significant decreases in numbers of X-rays, CRP and leukocytes determinations, and antibiotic prescriptions. Our data support the restrictive use of chest X-rays, CRP and leukocyte determinations in infants, admitted to hospital with RS virus bronchiolitis.