Question

Cindy has a full mutation for FMR1and her husband has no mutation.

a. What is the inheritance risk for their offsprings?

b. If Cindy has a pre-mutation (100 repeats) on one of her X chromosome, what would be the expected risk of having a child with full mutation?

c. Discuss molecular methods that would be appropriate to detect pre-mutations and full mutations.

Answer 1

Answer:

Dear Student ,

FMR1 stands for fragile X mental retardation 1. It is located on the X chromosome of humans. It codes for a protein, called fragile X mental retardation protein FRMP. This protein acts in controlling brain synapses and reproductive systems.  

a. In this very case , Cindy has high risks of passing on the mutation to her offspring. As this mutation is inherited by X linked dominant pattern.

In the eggs , the premutation repeats may extend to 200 CGG.

b. According to studies, less than 100 CGG mutation, has less risk of passing on the mutation.  

c. Usually , the detection is done using 2 methods, or clubbing 2 methods... viz PCR and southern blotting .

Here pcr is used to judge the number of repeats while southern blotting helps judge the extent of methylation that occurred.