Marfan syndrome (MFS) is an autosomal dominant disorder caused by mutations in 
the fibrillin 1 gene (FBN1). Neonatal form of MFS is rare and is associated with 
severe phenotype and a poor prognosis. We report on a newborn girl with neonatal 
MFS who displayed cyanosis and dyspnea on the first day of life. The main 
clinical features included mitral and tricuspid valve insufficiency, aortic root 
dilatation, arachnodactyly, and loose skin. Despite the presence of severe and 
inoperable heart anomalies, the girl was quite stable on symptomatic treatment 
and lived up to the 7th month of age when she died due to cardiorespiratory 
failure. Molecular-genetic studies revealed a novel intronic c.4211-32_-13del 
mutation in the FBN1 gene. Subsequent in vitro splicing analysis showed this 
mutation led to exon 35 skipping, presumably resulting in a deletion of 42 amino 
acids (p.Leu1405_Asp1446del). Interestingly, this mutation is localized outside 
the region of exons 24-32, whose mutation is responsible for the substantial 
majority of cases of neonatal MFS. Although the family history of MFS was 
negative, the subsequent molecular genetic examination documented a mosaicism of 
the same mutation in the maternal blood cells (10-25% of genomic DNA) and the 
detailed clinical examination showed unilateral lens ectopy.