Human Genetics
How do you use family data to make maps?
Human Genetics: How to get maps? - Lod Scores developed by Newton E. Morton
Standard analysis using grandparents
In family 1 the father carries A and B, and it is known that he inherited A from his mother and B from his father, so if A and B are linked he must be of constitution Ab/aB. His wife is ab/ab and, of four children, two are Ab/ab and two aB/ab.
The probability of the families turning out in this way if the recombination frequency (f) between A and B is, f can be calculated as follows. There are four possible kinds of gametes from the doubly heterozygous parent, two non-recombinant (parental) each with the frequency (1 - f)/2 and two recombinant each with frequency f/2. We classify the progeny just as recombinant, probability f, and non-recombinant, probability (1-f)
Since all four progeny are non-recombinant each has the probability of (1 - f). The probability of four non-recombinant progeny in this family is (1 - f)*(1 - f)*(1 - f)*(1 - f) = (1 - f)4 [* = multiplication ].
Tabulation of this example allowing f to vary from 1 to 50 centimorgans.
Text iGenetics by Peter J. Russell
This web site is provided for instruction in Botany and Zoology 342
by Kenneth G. Wilson,
Professor of Botany
Miami University
wilsonkg@muohio.edu
