Question

Marfan Syndrome, one of the most common inherited disorders of connective tissue, is caused by an autosomal dominant mutation within the fibrillin-1 gene (FBN1) on the short arm of chromosome 15. Pooled ten-year records from several large hospitals in the United States revealed that, among 5,000,000 live births (=10,000,000 gametes), the total number of babies born with Marfan Syndrome was 250. Among those 250 babies, 187 of them had at least one parent with Marfan Syndrome, and the remaining babies were born to two unaffected parents. What is the spontaneous mutation rate for Marfan Syndrome?

Answer 1

1. Spontaneous mutations in the FBN1 gene account for approximately 25% of cases. The likelihood of such a mutation is quite uncommon, occuring in about 1 of 20,000 births. It is caused by a mutation gene FBN1 that creats problems in a protein called fibrillin-1. Fibrillin-1 is an essential component of connective tissue.
2. Three out of every four people with marfan syndrome inherit the disorder from a parent with disease. One out of four have a spontaneous mutation in the gene, which means that neither of the parent has marfan syndrome.
3. Marfan syndrome affect both sexes and all ethnic groups. About 1 in 5000 people are born with the disorder.
4. It is an autosomal dominant condition. This type of inheritance means each new child of an affected parent has a fifty percent chance of inheriting the disease.
5. The diagnosis of marfan syndrome remains a clinical one. There is a wide range of variability in the manifestation of the disease within and amoung the families.
6. Also many individuals without the syndrome have one or more clinical features, that suggest that they may have marfan syndrome, common features include tall and thin stature, eye problems.
7. People who are suffering from marfan syndrom suffer from abnormal curvature of the eye, myopia, the connective tissue defect can affect the cornea, lens and growth of eye.
8. There is no cure for Marfan syndrome at this time, but the earlier detection and awareness helps to improve the quality of the life.
9. Marfan syndrom can affect the heart, blood vessels, skeletal system, skin, lungs.