Isolated ectopia lentis is usually autosomal dominant and commonly due to the 
mutations of FBN1 gene. We report on a family with ectopia lentis. The 
propositus is a 6-year-old boy with bilateral superior-temporal ectopia lentis. 
His echocardiogram was normal and he did not meet the revised Ghent criteria for 
Marfan syndrome. Molecular genetic testing revealed c.1948 C>T (p.Arg650Cys) in 
FBN1. The mother has visual acuity of 20/20 with -4.50 right eye and -2.50 left 
eye. She has no evidence of ectopia lentis. DNA analysis revealed that she has 
the same FBN1 mutation. Seven other maternal family members also have ectopia 
lentis. In conclusion, we report on a case of early-onset autosomal dominant 
isolated ectopia lentis caused by FBN1 mutation that has previously been 
reported only in Marfan syndrome. The child's mother presumably represents a 
rare case of nonpenetrance.