Another one bites the dust The medical geneticist was asked to consult on a case of suspected Huntington’s disease. The patient was a 56 year old male who was referred by a neurologist because of characteristic movements suggesting Huntington’s disease. His wife reported that he was becoming progressively disorganized and unable to do simple calculations. Can you help me with this case I have? Sure. I can try and help

Another one bites the dust No. I am not aware of a family history of Huntington’s disease. Sadly, his father committed suicide when he was 50. His wife was adopted. He’s got a granddaughter with PKU, though. You may know her. Michelle Chance. He has 3 surviving children. A 4th child died in a car crash years ago. Oh boy. I think I see where this is going. His mother died of cancer at 70. He has a 55 year old brother and a 52 year old sister. Any family history?

The entire Chance family

Are we sure there is no family history?

Another one bites the dust Paul, we’re pretty sure we’re dealing with Huntington’s disease. If we’re right, there’s not much that we can do for your dad except keep him comfortable. He’s given us permission to take some blood for testing. I’m going to get you information to contact local and national Huntington’s disease support organizations. They are great at offering emotional support. What might be done to make Dad more comfortable? Can we help to relieve Mom’s burden?

Huntington’s Disease Autosomal dominant Death of nerve cells in brain Signs show around middle age Due to defective (misshaped) gene

Woody Guthrie: This Land is Made for You and Me

Video about Huntington's disease Autosomal dominant disorder Brain cells start to die in late 30’s Causes uncontrollable muscle movements Death usually in 40’s-50’s No treatments Click if YouTube video doesn’t work

At the geneticist’s request, Paul returns with Deborah and Susan At the geneticist’s request, Paul returns with Deborah and Susan. During the meeting, the geneticist revealed that Alexander (their father) indeed had molecular evidence of HD. There is a 50-50 chance that each of you has inherited the HD gene. We can directly check for changes that are associated with Huntington’s disease. The testing is pretty accurate. 36 or more of these CAG repeats and you’ll eventually develop the symptoms. Fewer than 30 repeats and you don’t have to worry. He has 57 of CAG repeating DNA nucleotides. I’m afraid that your father has Huntington’s disease. This is an autosomal dominant disorder. Does that mean that we’ll probably end up like dad too? Can’t anything be done?

H h h H h h h h H h h h Key H = Huntington’s allele h = Healthy Alexander (father) H h h H h h h Carolyn (mother) h H h h h

Susan, this information would change your life forever Susan, this information would change your life forever. Right now, you don’t know if you’ve inherited the gene. The test results will either be very reassuring, or devastating. Either way, the results would be difficult to deal with. That goes for each of you. Well…I’d have to tell Dan. Then I guess drop out of school. Maybe I’d just have one big party with whatever’s left of my life. I don’t know. Maybe try to do something important with my life. I don’t know. And what would you do if the results indicate you have HD? I’d like my blood tested immediately.

For the next hour the process of determining whether or not each of them inherited the HD gene was reviewed with them. When they left, the geneticist knew that…. …each will be making one of the most difficult decisions in their lives. No testing will be undertaken without extensive counseling to assist with your decision. And to help you cope with the results, whatever the results may be. I can start the process for you, but each of you will eventually need to take a chance… or make a choice. The End