Which of the following genotypes would most likely lead to a low birth weight and a small placenta?
|A. Igf2+/Igf2- where the mutated Igf2- allele comes from the paternal source.|
|B. Igf2+/Igf2- and it doesn't matter which parental source the mutated Igf2- comes from.|
|C. Igf2+/Igf2- but only in female progeny as the Igf2 gene is on the X-chromosome.|
|D. Igf2+/Igf2+ where neither maternal nor paternal allele is mutated.|
|E. Igf2+/Igf2- where the mutated Igf2- allele comes from the maternal source.|
The IGF2 is an insulin like growth factor associated with growth defects. The IGF2 which comes from mother is always silenced, this means maternal copy is not expressed. The copy received from father makes the difference. The paternal copy if mutated or knowcked out, will results in low birth weight and growth defects. Hence answer is option A