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I am asked to fill the genotypes in the spaces provided but looks like I am aving a little bit of trouble. can anyone help? thanks in advance!


1 Answer 1


Here are a few hints that might help:

Talking about Maria's pedigree: Firstly, it seems as if you have mixed up with $X^a$ and $X^A$, see that the disorder is X-linked DOMINANT. Anyone with either heterozygous or homozygous dominant expression would have the disease expressed. So the first generation male should have a genotype: $X^aY$, because if it were $X^AY$ then Amelogenesis imperfecta would be expressed as his phenotype and the first generation female should have a homozygous recessive genotype. Also no child in the second generation would suffer from the same. (NOTE: The one suffering from Amelogenesis in the second generation would have genotype $X^AY$)

As for Gunther disease, both the parent in the first generation should have a heterozygous dominant expression and the offspring suffering must have a homozygous recessive expression. And you can apply the same basics in Peter's pedigree.

I think this much should be enough to complete the task, but if you still have some doubt you can put it forward in the comments.

  • $\begingroup$ Thank you very much Shefali for the explanation. I truly appreciate it. Here is my second attempt: s837.photobucket.com/user/apothemnew/media/… does it look ok now? Thanks in advance. Sorry for the inconvenience :) $\endgroup$ Jan 27, 2014 at 3:34
  • $\begingroup$ Well, in the first place I did not understand what does H or h and - indicate? $\endgroup$
    – Shefali
    Jan 27, 2014 at 7:05
  • $\begingroup$ @ApothemCyte U have written Gg for peter's father but he could also be GG ! $\endgroup$
    – biogirl
    Jan 27, 2014 at 8:18
  • $\begingroup$ @Shefali Hello Shefali. Would you please if at all possible be able to help with my new question: biology.stackexchange.com/questions/15142/… Thank you so much in advance!! $\endgroup$ Feb 19, 2014 at 17:02

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