Early onset ectopia lentis due to a FBN1 mutation with non-penetrance.

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.