Compound heterozygous mutations in FBN1 in a large family with Marfan syndrome

Abstract

Abstract Background Marfan syndrome (MFS) is a dominant monogenic disorder caused by mutations in fibrillin 1 (FBN1). Rarely, compound heterozygosity for FBN1 mutations has been described. Methods A large kindred with MFS was assessed clinically over decades, and genetically using exome and/or Sanger sequencing. Results A previously identified FBN1 missense variant (p.Tyr754Cys) was confirmed in all subjects with MFS. An additional variant (p.Met2273Thr), previously associated with incomplete MFS, was identified in three siblings. These three compound heterozygous individuals had aortic dilatation at early age (all 40 years but not requiring surgical intervention. Another heterozygous (p.Tyr754Cys) sibling did require aortic root repair (28 years). The heterozygous (p.Met2273Thr) mother had aortic dilatation diagnosed at age 68 years but has not required surgical repair. Conclusion Although compound heterozygosity or homozygosity is rare in MFS, it should be considered when there is an unusually severe phenotype in a subset of family members.

Keywords

• compound heterozygous
• FBN1
• fibrillin 1
• Marfan syndrome