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N223 genetics quiz 1

Terms in this set (90)

Autosomal dominant

Is it autosomal dominant? Well, I do see that every affected person seems to have one affected relative, so that one could be right.
Is it autosomal recessive? Well, if that were the case, then we would have a lot of carriers; the boy the first generation would be a carrier, the first boy in the second generation would be a carrier, as would the wife at the end of the second generation. So, not the most likely because if it were autosomal recessive, we would need, yeah, a lot of carriers in this family. Could it be X-linked recessive? It can't be X-linked recessive because we have this affected daughter in the fourth generation with the arrow next to her, and if it were X-linked recessive, she would have two copies of the disease causing allele, in which case should have gotten one from her father, and he would have to be affected. Could it be X-linked dominant? Well, we're seeing on the second generation that last affected male has an affected son, and his wife is not affected, so it's not gonna be X-linked dominant because then that woman at the very end of generation two would need to be affected. It's not mitochondrial because we have affected mothers not passing it on to all their kids, and affected dads passing it onto their kids, so that's not possible. It's not Y-linked because it affects women in the pedigree. It's not impossible to tell the correct answer is: the most likely would be autosomal dominant. It does not skip generations, it affects males and females, and both men and women are passing it on to both sons and daughters, so the correct answer is Autosomal Dominant.
X-linked dominant
X-linked recessive

Could this be autosomal recessive? Could be; we'd have a whole lot of carriers though, so to have affected kids, we would need to have the person in the first generation who's a male be a carrier, as well as the second generation, first male and the last female, but it's not necessarily ruled out.
Could it be X-linked recessive? This one it could not be, and the reason we can tell is this individual in the third generation, the first female who has the arrow pointing to her, she has two recessive, disease causing mutations, and so she would need to get one from mom, and one from dad, and if dad had a single mutation he would be affected. He's not, so it cannot be X-linked recessive. Could it be X-linked dominant? Well, it can't be X-linked dominant because then the male in the third generation at the end of the pedigree, he would have had to have an affected mother because he's got one X, he gets it from her. She's healthy; it can't be X-linked dominant.
Mitochondrial; this doesn't look like that at all. We see dad's passing it on, affected mothers with some unaffected kids; it's not Y-linked because we see women in the pedigree with it, so this one could not be Y-linked recessive. It could not be X-linked dominant, it could not be mitochondrial, and could not be Y-linked, but it could be any other mode of inheritance. It's most likely to be autosomal dominant because we see a transmission from mother to sons and daughters; dads can pass it on to their sons, as well as their daughters; we don't see any skipping generations; and it occurs in about equal frequency in males and females, so autosomal dominant is most likely. But it cannot be X-linked recessive, X-linked dominant, or mitochondrial, or Y-linked, so the correct answers are: X-linked recessive, X-linked dominant, mitochondrial, and Y-linked.