Abstract: Objective　To improve the understanding of clinical phenotype and genotype of Marfan syndrome (MFS). Method　Clinical data of Marfan syndrome with FBN1 gene mutation in a child was retrospectively analyzed and related literature was reviewed. Results　A 4-year-4-month-old girl had a special facial features (long face, hypertelorism, high palatal arch) and spider-like fingers and toes. The patient is slender with a height of 115.0 cm (>P97), the span of upper limbs is 118.8 cm, the upper part is 60 cm, the lower part is 55 cm, and the weight is 19 kg (P50~P85). A grade II/VI systolic murmur could be heard at the apex of heart. Color echocardiography showed an atrial septal defect (4 mm), mitral valve disease with moderate regurgitation, tricuspid valve disease with mild to moderate regurgitation, and slightly widened sinus valsalva of the aorta. Cardiac CT showed the enlargement of left atrial and left ventricular. The chest radiograph showed the patchy shadow of the right lung, a slightly plump shadow of the heart, and locally uplifted right diaphragm. The patient had a history of right upper limb fracture and suffered from binocular ametropia. DNA was extracted from venous blood of child and her parents, and gene detection was performed by exon chip capture and high throughput sequencing. The results showed that there was a c.865 dupA heterozygous mutation of FBN1 gene in the child, which had not been reported. The mutation resulted in amino acid conversion from isoleucine (Ile) to asparagine (Asn) at position 289 and amino acid conversion from aspartic acid (Asp) to termination codon at position 290, leading to the early termination of amino acid coding. Pedigree examination showed that the mutation originated from the father of the child, and the father also had MFS with heterozygous mutation. Conclusion　A new exon heterozygous mutation of c.865dupA in FBN1 gene was found to cause MFS.

Key words: Marfan syndrome;　FBN1 gene;　heterozygous mutation