The IGF-2R gene is is autosomal and maternally imprinted (silenced). Supposing t
ID: 48761 • Letter: T
Question
The IGF-2R gene is is autosomal and maternally imprinted (silenced). Supposing that two alleles for this gene have been defined that are distinguishable by the electrophoretic mobility of their protein products. One allele encodes a 60K serum protein, the other a 50K serum protein. The mother in a couple, expresses the 60K protein, the father expresses only the 50K protein. Among their two children, the daughter expresses only the 50K protein, whereas the son expresses only the 60K protein.
From these data, what can you say about the genotype of I-1(the father). (Hint: IGF-2R alleles from which of the parents are being expressed in the kids?)
The son (II-2), expressing the 60K protein, sires two children one of which expresses the 60K protein and the other the 50K protein. What is his genotype?
What is the genotype of his mother (I-2)?
60K 50K 60K O6ok 60KExplanation / Answer
IGF-2R gene means insulin growth factor 2-R. Maternal imprinting suggests that the gene coding this is silenced in the mother. There will be methylation in the DMR (Differentially methylated region) of mother. This leads to the expression of the mother allele twice . Thus the genotype of the offspring generated is expressed based on the genotype of the maternal parent.
The silencing gene is expressed as igf2- and the functional gene is expressed as igf2. Based on from where the genes are passed the offsprings phenotype is determined.
The father genotype is igf2igf2 and the mother will be igf2-igf2-. Thus the son will be dwarf with a non-functional igf geneigf2-igf2- and the daughters will be normal .
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