Neurofibromatosis type 1 and Noonan syndrome are both common genetic disorders 
with autosomal dominant inheritance. Similarities between neurofibromatosis type 
1 and Noonan syndrome have been noted for over 20 years and patients who share 
symptoms of both conditions are often given the diagnosis of 
neurofibromatosis-Noonan syndrome (NFNS). The molecular basis of these combined 
phenotypes was poorly understood and controversially discussed over several 
decades until the discovery that the syndromes are related through disturbances 
of the Ras pathway. We present an infant male with coarse facial features, 
severe supravalvar pulmonic stenosis, automated atrial tachycardia, hypertrophic 
cardiomyopathy, airway compression, severe neurological involvement, and 
multiple complications that lead to death during early infancy. The severity of 
clinical presentation and significant dysmorphic features suggested the 
possibility of a double genetic disorder in the Ras pathway instead of NFNS. 
Molecular analysis showed a missense mutation in exon 25 of the NF1 gene 
(4288A>G, p.N1430D) and a pathogenic mutation on exon 8 (922A>G, p.N308D) of the 
PTPN11 gene. Cardiovascular disease has been well described in patients with 
Noonan syndrome with PTPN11 mutations but the role of haploinsufficiency for 
neurofibromin in the heart development and function is not yet well understood. 
Our case suggests that a double genetic defect resulting in the hypersignaling 
of the Ras pathway may lead to complex cardiovascular abnormalities, 
cardiomyopathy, refractory arrhythmia, severe neurological phenotype, and early 
death.