File talk:Autosomal Dominant Pedigree Chart.svg
I'm lost. The 50% chance can't be expressed with 5 children? Why show the outcomes of the two non-procreating womens? — Preceding unsigned comment added by 70.126.175.4 (talk • contribs)
- I agree, it does not make sense to me either. The only way to understand it is to read the text. /Cygnus78 (talk) 22:04, 19 April 2008 (UTC)
The image should also show the status of children by two affected parents. VegaDark (talk) 05:57, 16 August 2008 (UTC)
- I want to ask, is the "disease" not sex-linked? Or else the pedigree would not be possible.
From F2, the F1 mother is heterozygous. (There are both affected and wild type boys and girls) As phenotype of F1 mother is wild type. Hence, affected allele is recessive. Let X and x be the allele controlling wild type and affected characters respectively. Then the genotype of the girl at the most right is xx. The phenotype of the husband is XY, how come there is wild type son and affected daughter? Thanks!
Xdragonaite (talk) 09:27, 8 December 2008 (UTC)
Needs explanation re: genotype, not just phenotype, of affected person
For a proper explanation of a chart re: autosomal dominant (AD) inheritance, we need to distinguish between affected-homozygous and affected-heterozygous. This chart is clearly re: an affected heterozygote father — otherwise there wouldn't be any unaffected children — but it doesn't say that.
Maybe the chart's developer assumes that the disease in question is so rare that the chances of two affected parents' surviving to reproductive age, actually meeting, reproducing once they have met, etc. is zero, such that a) no person homozygous-dominant for this disease could ever be created (or the chance of a given man's and a given woman's both being affected is smaller than the number of people in the world / atoms in the universe / whatever) and therefore b) for any affected person, it's safe to assume that the person is in fact heterozygous. However, that's a pretty big assumption, especially when the chart purports to show a general pattern rather than being specific to a named disease that is in fact that rare.
Why not just draw four Punnett squares as follows?
- Homozygous-D & unaffected (Aa x 4)
- Heterozygous-D & unaffected (Aa x 2, aa x 2)
- Homozygous-D & heterozygous-D (AA x 2, Aa x 2), and
- Heterozygous-D and heterozygous-D (AA x 1, Aa x 2, aa x 1)
Just an idea...
- Antediluvian67 (talk) 21:00, 4 May 2011 (UTC)
