Problem 1 A young woman consults a geneticist during her first pregnancy. Her brother was previously diagnosed with Duchenne muscular dystrophy and had since died. The woman had been tested biochemically and found to have elevated creatine kinase levels indicating she is a carrier of the disease. Unfortunately, no DNA analysis had been conducted on the woman’s brother to determine whether the mutation in his DMD gene was a deletion. The woman was investigated by molecular analysis and found to be heterozygous (A1/A2) for a microsatellite marker closely linked to the DMD gene. No relatives except the parents of the woman were available for analysis. –a. Can the phase of the mutation in the woman be determined from analysis of the available individuals? –b. Can this information be used to diagnose her pregnancy? –C. What other molecular analysis could be performed on the fetus?

Answer Problem 1 A young woman consults a geneticist during her first pregnancy. Her brother was previously diagnosed with Duchenne muscular dystrophy and had since died. The woman had been tested biochemically and found to have elevated creatine kinase levels indicating she is a carrier of the disease. Unfortunately, no DNA analysis had been conducted on the woman’s brother to determine whether the mutation in his DMD gene was a deletion. The woman was investigated by molecular analysis and found to be heterozygous (A1/A2) for a microsatellite marker closely linked to the DMD gene. No relatives except the parents of the woman were available for analysis. –a. Can the phase of the mutation in the woman be determined from analysis of the available individuals? Yes. The phase can be determined from analysis of her father, who transmitted a normal X chromosome to the woman. –b. Can this information be used to diagnose her pregnancy? Yes. If a male fetus received the grandpaternal X, it will be unaffected. If it received the grandmaternal X, it will be affected. This, of course, assumes no recombination in the transmitted chromosome and no gonadal mosaicism in the grandfather. –C. What other molecular analysis could be performed on the fetus? Deletion analysis

Problem 2 Advise –One of you is expecting a child. You have come to get some advice. –Each group has a specific disease –Use your own families to draw a pedigree –Pick an individual or individual in the family who is/are affected. –determine what test you think are valid Advisor –Ask questions to determine family history –Determine if prenatal diagnosis in indicated –What tests would you advise –Determine the risk –Suggest treatment and management