In familial retinoblastoma, are mutations in the normal RB1 gene always responsible for the loss of...

In familial retinoblastoma, are mutations in the normal RB1 gene always responsible for the loss of heterozygosity?

In a family with retinoblastoma, would the mechanism of loss of heterozygosity in tumors in different members of the family be expected to be same or different?

Cite some evidence supporting the conclusion that tumor cells are clonal.

A gene for hereditary prostate cancer has been mapped to chromosomal location 1q25; it shows autosomal dominant inheritance. How would you go about identifying the mutant gene?

What would be the expected result of nonsense mutation in Mad gene?

Would the mutation in the gene for Cdc20 protein expected to be dominant or recessive?

Solutions

Expert Solution

1) The retinoblastoma gene is a normal tumor supressor gene. Therefore, mutations in the normal RB1 gene is always responsible for the loss of heterozygosity and the devlopment of retinoblastoma.

2) The mechanism of loss of heterozygosity in tumors in different family members in case of retinoblastoma will be different.

3) The evidence supporting that tumor cells are clonal are,

clonal B cell origin of hairy cell leukemia
clonal T cell origin of Mycosis fungoidosis

4) Genetically map the gene to high resolution using molecular markers. This will help us to identify several closely linked molecular markers on each side of the disease gene. Then overlapping YAC, BAC, and PAC clones are obtained. Then, clones are used to probe southern blots to look for differences in fragments between normal and tumor tissue. Ultimately, one would sequence the DNA in the narrowly defined region and try to identify a sequence difference that segregates in the family that is associated 100 percent with the affected phenotype.

gladiator answered 1 year ago

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