Which inheritance pattern is associated with Marfan syndrome?

Which inheritance pattern is associated with Marfan syndrome?

• A. X linked recessive
• B. Mitochondrial
• C. Autosomal dominant
• D. Autosomal recessive

Answer: (C)

Marfan syndrome is inherited in an autosomal dominant pattern because a single mutant copy of the FBN1 gene on an autosome is enough to produce the disorder. Affected individuals often have a parent or child with the condition, showing vertical transmission, and each child of an affected person has about a 50% chance of inheriting the mutation. New mutations also occur, so someone can be the first in their family to show signs. The condition’s features come from defective fibrillin-1, leading to weakened connective tissue and involvement of the skeleton, eyes, and cardiovascular system; this explains why a single gene change can produce such a wide range of effects (variable expressivity). Other inheritance patterns don’t fit Marfan: X-linked recessive would bias toward males and show a different family pattern; mitochondrial inheritance would transmit through mothers to all offspring; autosomal recessive would require two mutated copies and typically shows affected siblings from unaffected parents.

Marfan syndrome is inherited in an autosomal dominant pattern because a single mutant copy of the FBN1 gene on an autosome is enough to produce the disorder. Affected individuals often have a parent or child with the condition, showing vertical transmission, and each child of an affected person has about a 50% chance of inheriting the mutation. New mutations also occur, so someone can be the first in their family to show signs. The condition’s features come from defective fibrillin-1, leading to weakened connective tissue and involvement of the skeleton, eyes, and cardiovascular system; this explains why a single gene change can produce such a wide range of effects (variable expressivity). Other inheritance patterns don’t fit Marfan: X-linked recessive would bias toward males and show a different family pattern; mitochondrial inheritance would transmit through mothers to all offspring; autosomal recessive would require two mutated copies and typically shows affected siblings from unaffected parents.