Introduction
Noonan syndrome (NS) [Mendelian inheritance in man (MIM) # 163950]
is a common autosomal dominant disease, with an estimated incidence rate
of 1/1,000 to 1/2,500 live births1. It is
characterized by obvious facial features, short stature, and congenital
heart defects, mild to moderate developmental retardation/learning
disabilities, skeletal abnormalities, cryptorchidism and
myeloproliferative diseases2. It is an autosomal
dominant disease with complete penetrance but variable expressiveness.
About 50% of patients with NS have missense mutations in protein
tyrosine phosphatase non-receptor type 11 (PTPN11) gene, with less
mutations in SOS1, RAF1 and KRAS genes, accounting for 13%, 10% and
less than 5% respectively3. About 30% of patients
with clinically confirmed NS are still negative4.
Intractable chylothorax in childhood is a rare and potentially
life-threatening disease, with an incidence rate of about
1:30,0005. Associations with genetic syndromes include
congenital lymphoid malformation syndromes such as Gorham-Stout, Optiz
G/BBB, Hennekam, Milroy and NS, as well as chromosomal abnormalities
such as Trisomy 21 or Turner syndrome6. Up to now,
there is no reports about the refractory chylothorax due to thoracic
duct stenosis in NS with RIT1 gene mutation.