Biology 321 Spring 2013 Assignment Set 3 Pedigree Analysis You are responsible for working through on your own the general rules of thumb for analyzing pedigree data to differentiate autosomal and sex linked traits see pedigree analysis guidelines in lecture material and Chapter 2 of text Chapter 2 Reread Section 2 6 Human Pedigree Analysis Examine solved problems 2 3 Work problems 13 14 45 51 52 57 58 64 74 79 Chapter 3 Optional Read very interesting section on Organelle genes and look at striking pedigree on pg 109 Required Problem Assignments in 9th edition of text http fire biol wwu edu trent trent assignmentset3 9 pdf Set 3 Problems sorted by analytical and or content type Sorting through the complexities of real data or ambiguous data see also ambiguous pedigrees This problem set 2 3 5 Sorting through small data sets where progeny count will not necessarily match predicted probabilities for each phenotypic genotypic class see most pedigrees This problem set 2 3 11 Basic Probability Product and Sum rules see also combining pedigrees and probability This problem set 1 Conditional probability limiting the possible outcomes see also combining pedigrees and probability Text Chapter 2 Solved problem 2 This problem set 1 Simple pedigree analysis This problem set 4 5 Ambiguous pedigrees Text Chapter 2 74 This problem set 4 5 6 7 8 9 10 Factoring allele frequencies into pedigree analysis Text Chapter 2 58 74 This problem set 3c d 4 7 8 10 1 Pedigrees and genotype assignment Text Chapter 2 51 52 64 79 This problem set You should define allele symbols and assign genotypes while working through most of these problems independent of whether they are specifically requested Combining pedigrees and probability Text Chapter 2 solved problems 2 3 51 58 79 This problem set 8 Basic Pedigree Problems Online Pedigree practice problems http www mansfield ohio state edu sabedon biol1128 htm Problem 1 Two individuals are heterozygous for an autosomal recessive allele a If they produce 3 offspring what is the probability that all three progeny have the dominant phenotype Show your work b Three offspring are produced from this mating and all three have the dominant phenotype Given this outcome what is the probability that all three are homozygous for the dominant allele Show your work c If they produce 3 offspring what is the probability that they have both types of progeny dominant and recessive NOTE there is an easy way to work this by extending your calculation f rom part a Show your logic and work Problem 2 The guidelines given to you in class were designed to help you learn how to interpret pedigrees Do not memorize these guidelines you should be able to generate each rule from the basic genetic principles of Mendelian and sex linked inheritance Look at each rule carefully For a pedigree to be consistent with a specific mode of inheritance which rules must be met Which rules might apply but are not absolutely required Under which circumstances would the latter apply or not apply Problem 3 a Does a study of pedigrees always permit a person to determine whether an allele is dominant or recessive b Why is it much easier to analyse human pedigrees for autosomal dominant traits than for autosomal recessive ones c Why are parents of individuals homozygous for rare recessive alleles likely to be related d Briefly discuss the conditions under which a recessive trait may appear to be inherited as a dominant one and vice versa and the precautions necessary in drawing conclusions from pedigree analysis Problem 4 2 What pattern s of inheritance can be ruled out for the following pedigrees What is the most likely mode of inheritance in each case assuming that the trait is very rare a d b c e f Problem 5 i Examine the pedigrees shown below Pedigree 4 is a consistent with autosomal recessive autosomal dominant X linked dominant and X linked recessive inheritance b consistent only with autosomal recessive inheritance c eliminates autosomal dominant inheritance only because both progeny are affected d I don t agree with any of these statements ii If all of the pedigrees are taken together and assuming no complications the mode of inheritance of this disease state must be a autosomal recessive b autosomal dominant c X linked dominant d X linked recessive e more than one mode of inheritance is consistent with all of these pedigrees 3 Problem 6 One day a man comes into the office of a genetic counselor He is suffering from a very rare genetic disease The genetic counselor puts together the following pedigree of the man s family The genetic counselor then tells the man that he cannot pass the trait onto his sons but that even if he marries a normal woman all of his daughters are out of luck they will all have the genetic disease i What mode of inheritance did the genetic counselor imply with his advice to the man a X linked recessive b autosomal recessive c X linked dominant d autosomal domiant e Y linked ii Do you agree with the conclusions of the counselor and the advice that he gave a Yes since the trait is very rare recessive inheritance is eliminated and the counselor s advice is sound b No Recessive inheritance is still a likely possibility and the man should have been informed of that c No Autosomal dominant inheritance is clearly indicated In that case if the man marries a phenotypically normal woman there is a 50 50 chance that any child would be affected d Yes and no The counselor has good reason to suspect X linked dominant inheritance but he should have also considered another mode of inheritance as a possibility e Yes and no The counselor was correct in his conclusion about the mode of inheritance but incorrect in his predictions about the possible progeny of the man 4 Problem 7 Examine the pedigree shown above For each mode of inheritance listed below indicated E this mode of inheritance is excluded by the data C this mode of inheritance is consistent with the data Autosomal recessive inheritance of the trait recessive allele is common in the population ARC Autosomal Recessive inheritance recessive allele is very rare ARR X linked recessive inheritance recessive allele is common XRC X linked dominant inheritance XD Autosomal Dominant AD X linked dominant only males show the trait dominant allele is very rare XDM Autosomal Dominant and only males show the trait ADM Y linked the gene specifying the trait is on the Y chromosome Y For each mode of inheritance that you excluded circle the portion of the