SARS-CoV-2 is a novel coronavirus that has rarely been associated with chylothorax. Patients with Noonan syndrome are at risk for developing chylothorax, especially after cardiothoracic interventions. We present the case of SARS-CoV-2 infection triggering the underlying tendency of a patient with Noonan syndrome to develop chylothorax who did not develop it even after prior cardiothoracic interventions. Patient presented in respiratory distress without hypoxia and was found, on imaging, to have a large right-sided pleural effusion, which was eventually classified as chylothorax. The patient was then started on a low-fat diet. Chest tube drainage substantially reduced the effusion in size, and it remained stable. Our report highlights that SARS-CoV-2 infection can cause the development of a chylothorax or a chylous effusion in patients with Noonan syndrome or among populations with a similar predisposition. A high index of suspicion in vulnerable patients or those not responding to traditional therapy should exist with providers, thus leading to the testing of the fluid to confirm the diagnosis.

Noonan syndrome is a multi-system genetic disorder and patients may suffer from hypertrophic cardiomyopathy. Previous studies have identified electrocardiographic features that may support a diagnosis of Noonan syndrome. In this two-centre retrospective study, we analysed typical Noonan syndrome-related electrocardiographic features in 30 patients with Noonan syndrome with hypertrophic cardiomyopathy and compared these with the electrocardiographic features in 15 children with sarcomeric hypertrophic cardiomyopathy. Typical Noonan syndrome-related electrocardiographic features are a negative aVF, small left precordial R-waves, large right precordial S-waves, and abnormal Q-wave. We also analysed electrocardiographic features of hypertrophic cardiomyopathy: ST-segment abnormalities and T-wave abnormalities. A negative aVF was seen in 83% of patients with Noonan syndrome-related hypertrophic cardiomyopathy in contrast to 27% of patients with primary sarcomeric hypertrophic cardiomyopathy (p < 0.001). An extreme QRS axis in the north-west was seen only in patients with Noonan syndrome-related hypertrophic cardiomyopathy. This QRS axis deviation is likely to be determined by the Noonan syndrome-related hypertrophic cardiomyopathy and not by the type of hypertrophic cardiomyopathy. There were no differences between the two groups in the frequency of large right precordial S-waves and small R-waves in the left precordial leads V5 and V6. However, an abnormal R/S ratio was more often seen in patients with Noonan syndrome-related hypertrophic cardiomyopathy (p < 0.001). Pathologic Q-waves were seen statistically more frequently in patients with sarcomeric hypertrophic cardiomyopathy (p = 0.009). The occurrence of ST-segment and T-wave pathology did not statistically differ between the two groups. Electrography can be of use in differentiating sarcomeric hypertrophic cardiomyopathy from Noonan syndrome-related hypertrophic cardiomyopathy.

Noonan syndrome is an inherited disorder caused by alterations in the RAS-MAPK pathway. There have been several identified genotype–phenotype associations made with respect to congenital cardiac lesions and Noonan syndrome variants, but limited data exist regarding single ventricle disease in this population. Here, we report two patients with PTPN11-related Noonan syndrome and hypoplastic left heart syndrome variants.

The prevalence of congenital left main coronary artery atresia is very low. We report the characteristics and long-term outcomes of four children with left main coronary artery atresia. Three patients had heart murmurs due to mitral regurgitation at less than 1 year old. Their myocardial ischaemia worsened on exercise with aging. In the fourth patient, hypertrophic cardiomyopathy and Noonan syndrome were suspected at 1 year old. The development of communicating arteries between the conus branch and the left anterior descending artery was detected at 7 years old. The left main coronary artery atresia was confirmed by a selective coronary angiogram at 15 years old. Congenital left main coronary artery atresia could not be diagnosed by two-dimensional echocardiography; however, the left coronary arteries were small. Two patients underwent coronary artery bypass grafting of the left anterior descending artery using the left internal thoracic artery at 3 years and 6 years old, respectively. Two patients had an angioplasty with a cut back at the orifice of the left coronary artery at 2 years old and 17 years old, respectively. Two patients had no cardiac events without medication for more than 30 years after the operation. We must differentiate the diagnosis of left main coronary artery atresia in the small left coronary arteries with mitral regurgitation during the first year. Coronary artery revascularisation and mitral annuloplasty are needed. The long-term outcome of both coronary artery bypass grafting and angioplasty were good. The degree of mitral regurgitation after surgery may affect the prognosis.

Noonan syndrome is the second most common genetic syndrome associated with congenital heart disease after Trisomy 21. The two most common cardiac lesions associated with Noonan syndrome are pulmonary stenosis and hypertrophic cardiomyopathy. Although the incidence of mitral valve disease in Noonan syndrome ranges between 2 and 6%, rapid progression of mitral valve dysplasia causing severe mitral valve regurgitation and left atrial dilatation is seldom seen. Most cases of mitral valve disease have been diagnosed either on routine echocardiographic surveillance or when presented with heart failure symptoms. We describe an 18-month-old boy with Noonan syndrome presenting in atrial flutter due to a massively enlarged left atrium caused by severe mitral valve regurgitation which developed and progressed in less than 17 months.

We present a case of sudden cardiac arrest in the field with complete neurological recovery in an 18-year-old athlete with phenotypic Noonan syndrome. Evaluation revealed interventricular septal thickness of 18 mm without left ventricular outflow tract obstruction and no other identifiable structural, electrophysiologic, or genetic abnormality except isolated heterozygous variant for desmoplakin DSP variant p.Lys2103Glu, with unknown clinical significance.

Noonan syndrome and related disorders are a group of clinically and genetically heterogeneous conditions caused by mutations in genes of the RAS/MAPK pathway. Noonan syndrome causes multiple congenital anomalies, which are frequently accompanied by hypertrophic cardiomyopathy (HCM). We report here a Tunisian patient with a severe phenotype of Noonan syndrome including neonatal HCM, facial dysmorphism, severe failure to thrive, cutaneous abnormalities, pectus excavatum and severe stunted growth, who died in her eighth month of life. Using whole exome sequencing, we identified a de novo mutation in exon 7 of the RAF1 gene: c.776C > A (p.Ser259Tyr). This mutation affects a highly conserved serine residue, a main mediator of Raf-1 inhibition via phosphorylation. To our knowledge the c.776C > A mutation has been previously reported in only one case with prenatally diagnosed Noonan syndrome. Our study further supports the striking correlation of RAF1 mutations with HCM and highlights the clinical severity of Noonan syndrome associated with a RAF1 p.Ser259Tyr mutation.

We report a 3-year-old boy with giant and atypical coronary artery aneurysms in the acute phase of Kawasaki disease, despite appropriate therapeutic intervention, in Noonan syndrome with a novel heterozygous PTPN11 mutation, c. 907 G>A (p.Asp303Asn). We hypothesised that this PTPN11 mutation might affect both hyperinflammation caused by Kawasaki disease and vascular fragility in the coronary artery, resulting in coronary artery aneurysms.

We describe a complex case of obstruction of the left ventricular outflow tract in one of Dr. Noonan's original patients. Intraoperative findings revealed pathology at the valvar, subvalvar and supravalvar positions. Patients with Noonan syndrome are traditionally described as having right-sided cardiac pathology. Review of the literature revealed left-sided lesions to occur in a substantial number of these patients. We therefore suggest the routine employment of cardiac ultrasonography in all patients with Noonan syndrome with attention directed toward left-sided pathology, as well as the frequent pulmonary valvar pathology.

We report right ventricular ultrastructure in a 20-year-old patient with Noonan's Syndrome. Initial left ventricular and septal myocardial hypertrophy, observed at 2 months without obstruction, progressed to biventricular involvement over 18 years. Histopathologic evidence of cardiomyocytic disarray, with ultrastructural evidence of myofibrillar disarray, confirmed typical biopsy findings of hypertrophic cardiomyopathy on the right ventricular side of the septum.