Marfan syndrome is an autosomal dominant disease caused by a mutation. Symptoms
ID: 51828 • Letter: M
Question
Marfan syndrome is an autosomal dominant disease caused by a mutation. Symptoms of Marfan syndrome include skeletal, optical, and cardiovascular abnormalities. Skeletal abnormalities include long fingers and toes, extreme lengthening of the long bones, scoliosis, rib and sternum abnormalities, among others. Optical abnormalities almost always include ectopia lentis, a dislocation of the lens into the anterior chamber of the eye. Cardiovascular abnormalities may also occur, which is largely responsible for the shorter life span of individuals with Marfan syndrome. Each patient with the mutant allele for Marfan syndrome displays at least one of the symptoms.Which of the following terms describe Marfan syndrome (select any that could apply based on the information given)?incomplete dominance, hemizygous trait, overdominance, incomplete penetrance, variable expressivity, pleiotropy.
Explanation / Answer
Marfan syndrome is a disease which is associated with variable expressivity. It is also an example of dominant negative mutation and haploinsufficiency. Expressivity is a term used in genetics to explain the variations in the phenotype caused among the individuals having the same genotype. This means the degree of expression or influence a gene has on a particular individual under the given conditions. In case of Marfan syndrome the disease shows a variation in the phenotype among different individuals despite all of them having the same mutation in the FBN1 gene on Chromosome 15. As the question mentions that each patient with the mutant allele for Marfan syndrome displays at least one of the symptoms, it shows the variation in the phenotype in different individuals caused due to the same mutation.
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