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Uncle Jacob has HD: Neurobiology and Neurochemistry of HD for Kids

Hannah Boutros

January 21st, 2016

This is a short story about Tommy and his family. Tommy is an 8th grader who loves learning about the brain. After his uncle is diagnosed with HD, Tommy decides to learn more about the neuroscience behind HD so that he can explain it to others.

Today is a Monday. It is Tommy’s first day back at school after Thanksgiving. He is sitting at his wooden desk slightly hunched over, cradling his head with his hands, fully alert. His eyes are fixed on his science teacher, Ms. Robinson, who is standing at the front of the classroom, flipping through her notes.

Tommy gazes at her expectantly. He has really been looking forward to today. Ms. Robinson had announced the day before Thanksgiving that when they return from the holiday, they would start a new chapter in biology—learning about the human brain.

Tommy has been waiting for this day since the very start of 8th grade. He has always found the brain to be fascinating, mysterious, and extremely powerful. Brains allow us to do anything we want. Thanks to your brain, you can sing, dance, laugh, cry, listen, write, study, run, jump, or play a sport. How is it possible that such complex thoughts and feelings come from a single place inside someone’s head?

For Christmas last year, when he was in the 7th grade, Tommy’s mother gave him a science textbook all about the brain. Tommy knew exactly what the gift would be when he picked it up, and he couldn’t help but smile widely. It was heavy, and he could feel the edge of the book’s cover. He unwrapped it and felt its untouched spine. Tommy was eager to run upstairs and start looking at it, but also wanted to preserve its pristine condition. On the front cover, he saw that it was a book for 11th graders. He felt a warm pride deep in his chest, grasped the book tightly and grinned at his mother.

Today, that book sits under Tommy’s bed at home. He brought it to school once, but it was pretty heavy to carry around. His friend Eric was curious to see the vivid illustrations in the book, and the two of them pored over it intently during recess. When Eric lost interest, Tommy tried to show his other friends, but they didn’t want to spend their playtime looking at a textbook. Tommy decided to bring it back home. He was a little upset, but his mother said that eventually his friends would be more receptive to hearing about how awesome brains are.

Tommy’s friend Eric always sits next to him in class, and this Monday morning is no different. He nudges a sleepy Eric under their shared desk, because the lesson is about to start. Tommy knows when Ms. Robinson is about to start teaching, because she always takes one last sip of coffee out of her dark red mug, and scribbles a little bit on the whiteboard to make sure her marker is working. He can tell that she is drinking coffee, because he can always smell its strong aroma from his seat at the front of the classroom. Tommy notices that she brought a clay model of the brain. He is resolved to pay attention to everything she says today, and to take notes furiously.

Ms. Robinson looks up at her class and launches into her lesson:

Good afternoon, everyone! Today we will be discussing the human brain. As you all know, the brain is a complex organ that helps you think, move, and feel. In adult humans, it weighs about three pounds and looks like a large, greyish-pink walnut. Just like a walnut, it is divided into two hemispheres, split right down the middle. I brought a model today to help illustrate this. Do you see how the brain is split into two halves? The left half controls the right side of the body and human speech. The right half controls the left side of the body and how we perceive space. For example, it is responsible for the perception of how distant or close two objects are to each other.

Some scientists say that the specific functions of these two hemispheres are what make us uniquely human. They help us process at a higher level, which distinguishes us from other animals. This high-level part of the brain is the most recently evolved, and is known as the cerebral cortex. In fact, each hemisphere is divided into four lobes, which you can think of as four areas of the brain: the temporal, parietal, occipital, and frontal lobes. Most animals do not have a cortex, but we do. It helps us to be creative, feel emotions, and accomplish complex tasks.

Below this walnut-like structure, we find the more primitive part of the brain, located at the base of the head near the neck. This part of our brain is very similar to that of other mammals. It is responsible for our balance and for bodily functions that we don’t consciously think about, like breathing, regulating heart rate, and sleeping. All mammals need to accomplish these functions in order to survive!”

She pauses to take a sip of her coffee and clear her throat. Tommy takes a moment to catch up on the notes he is taking. Ms. Robinson asks the class: “Are there any questions so far?” A student in the back raises her hand. “I have two questions. Which side is the front of the brain, and which is the back? And how is the brain connected to the rest of the body?”

Both great questions! The front of the brain is where the frontal lobes are. They are right behind your eyes. The base of the brain is closer to the back, and that is where the lower brain connects to the spinal cord. This is actually related to how the brain is connected to the rest of the body, which we will be discussing next!” Ms. Robinson beams at her class.

She continues: “The brain is part of the central nervous system. As such, it is made of nerve cells, which we also call neurons. These cells carry information, called an impulse, from your body to your brain, and from your brain to your body. So for example, if you touch something hot with your finger, a sensory receptor for heat on your finger will send an impulse to your spinal cord, which is in the central nervous system. Your spinal cord processes this information, and to avoid harming your skin, it sends an impulse back to your finger to say: “get away from the heat!” All this happens in less than a second, and you quickly remove your finger from the heat source. Your nerves connect the brain to different systems in your body, and also help muscles move in response to stimuli. So they actually help you do almost everything that you do in everyday life.”

Tommy pipes up: “Ms. Robinson, what is your favorite part of the brain?” She smiles at him, adjusts her horn-rimmed glasses, and says: “I really like the amygdala. It’s a very small structure above the primitive part of the brain, but below the cortex. It’s my favorite part of the brain because despite its small size, it is quite powerful. The amygdala is part of the limbic system, which is responsible for emotions, mood, and instinct. It also plays a role in attention and memory.”

At the end of the lesson, the bell rings- school is over for the day. Tommy grabs his backpack and follows Eric out of the room, shuffling his feet. His black and white Converse match Eric’s shoes. People often say that the two boys could be twins. They are the same height, and both sport a head of dark brown curls.

As they are walking through the yard towards the gate, Eric glances up at the line forming in front of the yellow school bus, and snorts. “How is it that the 3rd graders are always out of class before we are?” Tommy smiles, and looks for his younger sister Lily in the line. More specifically, he scans for a pink Dora the Explorer backpack, and quickly locates his sister. She is chatting excitedly with Eric’s little sister Madison. Tommy overhears her exclaim: “And we have leftover pumpkin pie!”

The boys join their sisters in line, and they clamor onto the bus. Eric and Tommy sit at the far back, and Madison and Lily sit right in front of them, as they have been doing all year. Eric unzips his backpack, rummages through it, and digs out a half-eaten sandwich. With his mouth full of cheddar cheese on rye, he asks Tommy: “So how was your holiday?

Tommy replies: “I had a lot of fun. My mom spent all day Wednesday and Thursday cooking. She made my favorite cheesy broccoli dish that we always have on Thanksgiving. The house smelled incredible! And my uncle, aunt, cousins and grandparents drove here all the way from Chicago.

That’s awesome. Sounds pretty similar to my Thanksgiving!”

Eric trails off just as the bus slowed down in front of Tommy’s house. All four kids eagerly look out the window at the garden, because Tommy’s father, Joe, is usually watering the yard at this time of day. He is not there today, but typically waves at the children and aims the water hose at the bus as if he is trying to spray the kids when they hop off. Tommy wonders why his dad is not there today.

Both boys jump up out of their seats, and nudge their sisters to get up as well. The four kids hop out of the bus, and part ways. Eric and Madison live right across the street from Tommy and Lily, so they do not have far to go.

Tommy notices that his backpack is heavier than usual today, and sets it down in the driveway. He is still thinking about Thanksgiving. He really did enjoy the holiday, but he did notice that his Uncle Jacob, who is his father’s older brother, was not acting like himself. On Thanksgiving, Uncle Jacob bumped into the dining table a couple of times. He also mumbled a lot and seemed to hesitate before speaking. Tommy noticed that Uncle Jacob was not smiling as often. After the family meal, Tommy overheard his parents whispering in the kitchen that they were worried about him. They convinced Uncle Jacob to stay in town over the weekend to have a check-up with the doctor on Monday morning.

Tommy looks up at his sister. Lily runs up to the house just as their father, Joe, and Uncle Jacob pulled into the driveway. The two men sit in the car for longer than usual, but the kids do not take notice. Tommy grabs his backpack and follows his sister into the house. “Mom, we’re home!” Lily shouts. Their mom is on the phone, facing the floor-to-ceiling glass window in their living room. Lily runs to her, and hugs her from behind. Their mom hangs up the phone, turns around, and leans down to embrace her daughter. “Hi, sweetie. How was school today?”

***

Their mom made a light lunch for the kids. They gobble down some hot tomato soup with grilled cheese, and head upstairs to do some homework. Tommy had been excited to tell his mom about everything he had learned at school about the brain, but she seems distracted. As Tommy takes his empty plate to the sink, he notices that his mother is looking at the driveway with worried eyes. He gives her a hug. “Mom, is everything okay?” She looks down at her son and says: “I hope so, honey. I’m worried about Uncle Jacob’s health. Why don’t you head upstairs to do your homework and I’ll come upstairs later to chat?” Tommy nods and squeezes his mother extra tight.

He heads upstairs, sits at his desk and unzips his backpack to pull out his math notebook. Just as Tommy is putting pen to paper, his mother knocks at his bedroom door and asks to come in. Lily peeks in from behind her mother’s skirt. The rest of the house is eerily quiet. Tommy asks: “Where are Dad and Uncle Jacob?” His mother replies, “They went for a walk.” She enters her son’s room and sits on the bed. Lily plops down next to her and says innocently: “Mommy, what did you want to talk to us about?”

        Their mom sighs. Tommy notices that her eyes are red and puffy. “Uncle Jacob is unwell. He has been diagnosed with Huntington’s Disease.”

Tommy’s stomach feels funny, and he stands up with shaky knees. He manages to walk over from his desk and sit next to his mother on the bed. She wraps her arms around her children and wipes away a tear. Lily looks both scared and sad. “Mommy, what does that mean?” Their mom continues: “We are still learning what this means. We know that it affects his brain, so Uncle Jacob will experience changes in how he thinks, moves, and feels. The doctors say that his condition will deteriorate over time, so it’s important to be grateful for the time we have together. It’s very important for us is to offer Uncle Jacob as much love and support as we can. When he and your father get home, give them both a big hug, okay?”

***

Soon after that, Joe and Uncle Jacob arrive back at the house. Tommy has never seen his father cry before, but he notices that his dad’s nose is redder than usual. Lily and Tommy had been sitting on the stairs, waiting patiently for them to get home. Tommy stands up, and walks over to Uncle Jacob. He extends a hand to his uncle, and helps him walk over the doorway. Uncle Jacob, whose hair is beginning to gray, smiles down at Tommy with crinkling eyes. “Thank you, Tommy.” Tommy buries his face in his uncle’s shirt, and Uncle Jacob holds him close. Lily, in the meantime, is hugging her father.

***

The following morning, the children sleepily munch on cereal for breakfast while their mother prepares their packed lunches to take to school. Knowing that orange juice is Tommy’s favorite part of the morning, Tommy’s mom decides to squeeze fresh orange juice for the kids to drink with breakfast. Uncle Jacob walks into the kitchen just as Tommy is gulping down the last of his juice. Lily smiles shyly at him. He stands at the doorway, and doesn’t make eye contact with anyone. Tommy’s mom glances at him with worried eyes. “Good morning, Jacob. Can I get you anything to drink? How are you feeling?” Uncle Jacob glances over at her, and manages a small smile. “I’m doing fine, thank you Sue for your hospitality. I think I’d like to hang out with the kids before they leave for school.”

Tommy is glad to see his favorite uncle join him at the table. He has never seen Uncle Jacob look sad before, and doesn’t really know how to act. Regardless, they chat about the upcoming day at Tommy and Lily’s school. Tommy quickly realizes that there’s no reason not to act just like himself! A few minutes later, Sue gently reminds the children that they need to make the bus, and everyone stands up to head outside to the curb. Uncle Jacob walks with the kids out the front door to see them off. Tommy hoists his backpack onto his shoulder and walks alongside his uncle. He notices that Uncle Jacob is not walking normally anymore. He is dragging his feet slightly, and also walking lopsided.

Eric and Madison are waiting on the sidewalk, watching the trio approach. Once Lily, Tommy and their uncle arrive at the curb, Madison looks pointedly at Uncle Jacob and asks: “You’re walking funny today.” Uncle Jacob cracks a smile but his eyes look sad. His voice trembles but he says: “I know. I have been feeling sick recently.” Tommy feels confused and sad. Madison shouldn’t have treated Uncle Jacob that way, even if she doesn’t know any better. She doesn’t even know Uncle Jacob that well.

Tommy hugs his uncle extra tight before boarding the school bus. He sits at the back next to Eric and leans his head against the glass window. People don’t understand why Uncle Jacob has been moving and behaving strangely. It probably has to do with changes to his brain, just like Tommy’s mother said. Tommy remembers his neuroscience lesson from yesterday, and decides he wants to learn more. He is resolved to find someone to explain it to him.

He would have asked Ms. Robinson if she knew anything about Huntington’s Disease, but his schedule does not include science class on Tuesdays. After school, Tommy runs upstairs to his bedroom and pulls the neuroscience textbook from last Christmas out from under his bed. Laying on his stomach on the bedroom floor, Tommy looks for a glossary at the back of the book. Under the letter “H”, he finds Huntington’s disease, and reads: “Huntington’s Disease is an inherited condition characterized by the breakdown of nerve cells over time. Progressive movement, cognition, and psychiatric symptoms tend to appear.”

                                                      

***

The next day, there is no school due to a teachers’ in-service day. Tommy accompanies his father and Uncle Jacob to a doctor’s visit, and is feeling ready to ask some questions about Huntington’s Disease. Tommy sits in the waiting room during Uncle Jacob’s check-up, and peeks his head in at the very end to ask Dr. Peterson if he has time to answer a few questions. Dr. Peterson emphatically nods his head to say yes, and Tommy steps inside the room, walks over to the bed where Uncle Jacob is reclining but wide awake. Tommy leans against the side of the bed, resting his hand on his uncle’s shoulder. Joe is sitting in a chair near the doctor’s desk.

Dr. Peterson, I really want to understand what happens in the brain when someone has Huntington’s Disease.”

That’s great, Tommy. Why is that?”

I find the brain really interesting, but more importantly, I want to be able to explain it to others who ask or are curious. People don’t seem to understand what Uncle Jacob is experiencing and I don’t want his feelings to be hurt.”

Well, young man, I really appreciate your sensitivity, and I’m sure your uncle does too. I’d be happy to give you an overview of the disease. Huntington’s Disease is also known as HD. It is quite rare—it affects about one in every 10,000 people in the United States, and usually appears between 30 and 50 years of age. Many of the symptoms of HD can be explained by changes to the brain. There are movement, psychiatric and cognitive symptoms. Movement symptoms of HD can include muscle spasms, tics, rigidity, and difficulty speaking. There can also be uncontrollable movements like twisting and writhing. Symptoms affecting the brain include difficulty learning new things, and impairment of spatial perception. For example, Uncle Jacob mentioned to me that he bumped into the table during Thanksgiving, and that might have happened because he thought it was further than it actually was in real life.

There can also be difficulty planning and multitasking, since information processing in the brain is slowed and altered. Uncle Jacob sometimes has difficulty communicating with others, because is has gotten hard for him to organize words in his brain. Lastly, depression is a common psychiatric symptom for HD. So it’s important to show Uncle Jacob lots of love and support.

Thanks Dr. Peterson, that’s really helpful. So what is happening in Uncle Jacob’s brain?”

Uncle Jacob’s ability to think, feel, and move is changing. This is happening because nerve cells, also known as neurons, in his brain are deteriorating in certain areas, like the basal ganglia and the cerebral cortex, which I’ll explain in a minute. HD is a progressive, neurodegenerative disorder: this means that over time, involuntary muscle movements develop, and the ability to think and remember deteriorates.

The disease affects the basal ganglia, which is part of a circuit linked to the thalamus. This part of the brain is most affected by the disease, and many of the symptoms result from damage to this circuit. The basal ganglia sits at the base of the brain, and is involved in the coordination of movement by muscles. In fact, the striatum in the basal ganglia is the first to lose nerve cells. As this happens, pathways between the basal ganglia and the motor cortex are damaged. This is why coordination of movement is affected in the disease. The motor cortex, usually responsible for the planning and execution of movements, can no longer do its job properly because it is not stimulated enough. This likely leads to the slow speed of motor movement of HD patients. Tommy, are you familiar with the word “cortex”?

Yes, I am. We just learned about it in class yesterday. I know that the cortex is the high-level part of the brain in humans.”

That’s right. If you were to look at a human brain, you would see gray on the outside and white on the inside. That’s because the cell bodies of our neurons are on the outside of our brains, and look gray: this part of the brain is the cortex. The extensions off those cell bodies project towards the center of the brain, and are white due to a fatty substance called myelin. Anyway, initial loss of cells in the basal ganglia leads to cell loss from other regions that are not getting feedback anymore. All of these things happen in the brain, and lead to behavioral symptoms that are visible to us.

OK. You mentioned that there are emotional symptoms. Does something in the brain lead to that?”

Indeed. Huntington’s Disease progressively damages the caudate nucleus, which is a relay station between the limbic system and the frontal lobes. The limbic system controls emotions, while the frontal lobes are really important in personality, in emotion regulation, and in responding to emotions. So in HD, there is a disconnect between emotion processing and response to emotions. This produces apathy or lack of interest, a common symptom of HD.

Dr. Peterson, do we have a cure for HD yet?”

Not yet, but researchers are hard at work trying to find one. There is a buildup of plaques in the brain that we still don’t understand, and lots of research is being done there. Scientists are currently trying to determine whether that is the cause of toxicity, because if so, we will know what to target for treatment. Meanwhile, there are therapies available to mitigate symptoms.

Thank you so much for explaining this to me.

“Of course, I am happy to help. Let me know if you have more questions.”

Tommy shakes Dr. Peterson’s hand, and Joe stands up to leave. Along with Uncle Jacob, they make their way out of the office.

***

The next day is Thursday. It’s been exactly a week since Thanksgiving, but to Tommy, it feels like much longer. So much has happened, and his life feels like it has changed very much. At breakfast that morning, Tommy sits next to Uncle Jacob so that he can crack jokes and try to make his uncle laugh.

On the bus, Eric is playing with a Rubik’s cube. He and Tommy talk about the toy for a while, and marvel at how difficult it actually is to solve them. Madison and Lily, who are sitting in front of their brothers, notice how much fun the boys are having. They turn around to face Eric and Tommy, and watch the boys play with the cube. The four of them chat about the toy.

A while later, shortly before arriving at school, Tommy remarks to Madison: “Hey, do you remember the other day when my uncle was walking funny?”

She looks at him with large brown eyes. “Yeah. He said he was sick. I hope he’ll be ok!”

Tommy replies: “Thanks, Madison. He has Huntington’s Disease, which does not have a cure. Over time, his ability to think, feel and move will be affected more and more. I am hoping that we can all treat him with respect even if he moves or acts differently than we do. Over the week I spent some time learning about the changes that happen in the brain due to Huntington’s Disease, so if you’re curious about that I can try to explain it to you!”

Madison nods energetically. “I understand. Thanks for explaining that to me.”

Tommy smiles. “Of course!”

He sits back in the cushy bus seat, feeling much better. Tommy is confident that with the right words, he can help people understand that HD patients are just people too. Madison is a little young to hear about the changes HD causes in the brain, but he knows the knowledge will come in handy in the future. Tommy grips his backpack and excitedly sways his legs, eager to get off the bus. Maybe Ms. Robinson will have something to say about this too.

Up next: Tommy learns about the genetics of Huntington’s Disease. His cousin, Uncle Jacob’s son, is debating whether or not to get tested next year when he turns 18. Stay tuned for another short story, where Tommy learns about genetic testing and how HD is transmitted in families.

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Bryan’s Dad has Huntington’s Disease (Text)

Introduction^

Fig AC-1: Intro

Scenes 1-4^

Fig AC-2: Scene 1

When Bryan was younger, he used to love playing baseball with his dad. Every day after school, Bryan’s dad pitched to him and helped him become a very good hitter.

Fig AC-3: Scene 2

Almost every time Bryan’s friends came over to play, his dad would go outside and play with them. He would throw passes to them when they were playing football and he would shoot baskets with them when they were playing basketball. All of Bryan’s friends liked Bryan’s dad because he was so much fun to play with!

Fig AC-4: Scene 3

One summer, Bryan’s dad started to act a little strangely. When he walked, his hips moved around almost like he was dancing. When they played baseball, he began to throw pitches that missed the plate a lot (he used to throw perfect strikes). When Bryan’s friends came over, his dad could not throw passes or shoot baskets as well as he had before. Soon, his dad stopped playing with them.

Fig AC-5: Scene 4

Bryan was sad and confused about why his dad was having so much trouble moving around. He became even more concerned when he noticed that his dad was treating his mom differently. Bryan’s dad had always been very nice, but now he began to start arguments with Bryan’s mom and he sometimes said mean things.

Scenes 5-8^

Fig AC-6: Scene 5

Soon, Bryan returned to school. One day when his dad came to take Bryan home, Bryan’s friend Lisa said, “Your dad walks funny!” This comment made Bryan sad and angry because nobody had ever said anything bad about his dad before. Bryan was not just upset at Lisa, but also at his dad for becoming so different.

Fig AC-7: Scene 6

On the way home, Bryan’s dad noticed that his son was upset. He asked Bryan what was wrong and Bryan replied, “What’s going on with you, Dad? You don’t play sports as well as you used to, you walk really weird, and you haven’t been very nice to Mom lately. Why are you being like this?”

Fig AC-8: Scene 7

Bryan’s dad had noticed these changes in himself, too, and he told Bryan that he did not know why he was acting this way. “Actually,” he said, “your mom and I are going to see the doctor today to find out what’s going on. You are welcome to come along if you want.” Bryan never liked going to the doctor’s office, but he decided to go with his parents this time because he really wanted to know why his dad was acting so strangely.

Fig AC-9: Scene 8

When they got to the doctor’s office, the doctor asked, “So what seems to be the problem?”

Before his dad could speak, Bryan’s mother said to the doctor, “Well, my husband has been acting strangely the past few months. His body seems to shake when he walks and he has also been kind of grouchy.”

Bryan added, “We used to play sports together all the time, but lately he hasn’t been throwing as well as he used to and he even stopped playing with me and my friends.” Bryan’s dad looked sad when he heard his family say these things, but he knew there was truth in what they said.

Scenes 9-12^

Fig AC-10: Scene 9

The doctor replied, “There are a lot of different things that can cause these kinds of problems, so I will need to find out some more information.” She went on to ask Bryan’s dad about many different things, including how old he was and if any of his family members ever had a disease.

Bryan’s dad replied, “Well, I am 35 years old and my mom passed away when I was 27 from something called Huntington’s disease.”

Fig AC-11: Scene 10

Then Bryan heard his dad say this, he asked the doctor, “What is Huntington’s disease?”

The doctor replied, “Well Bryan, Huntington’s disease is a disease that can cause a lot of changes in the way someone moves, thinks, and feels emotions. These changes start to show up usually when the person is between 30 and 50 years old. The disease is generally passed down through families. Just like when you flip a coin and you have a 50% chance of the coin landing on ‘tails,’ a parent who has Huntington’s disease has a 50% chance of passing it on to his or her child. Both men and women can get the disease and it occurs all around the world, although it is generally very rare.”

Fig AC-12: Scene 11

Bryan’s dad asked, “So how do these changes come about?”

The doctor replied, “Well, the brain is made up of millions of small living cells called nerve cells and these basically allow us to do everything we do, from talking and reading to walking and even throwing a baseball. In people with Huntington’s disease, many nerve cells are damaged in certain parts of their brain called the basal ganglia. Healthy nerve cells in these parts of the brain help with making the smooth movements that we normally make when we do things like walking or playing catch. So when these nerve cells are damaged, this can lead to a lot of problems with movement.”

Fig AC-13: Scene 12

Bryan asked, “What is wrong with the nerve cells? Why are they damaged?”

The doctor replied, “The problem actually exists down within the nerve cells in tiny, microscopic structures called genes. The word sounds the same as the jeans you wear on your legs, but these genes inside the cells work in a completely different way. They contain a special kind of information in the form of DNA. Have you heard about DNA?”

Scenes 13-16^

Fig AC-14: Scene 13

“Only a little, in the news and at school.” said Bryan. “I don’t really understand it. What does it do?”

“Well,” said the doctor, “DNA is chemical stuff in the body’s cells that carries information for sustaining life. Each cell in the body has DNA that contains many thousands of genes, but the problem in Huntington’s disease has to do with just one of these genes, one small piece of the DNA that is called the Huntington gene.”

Fig AC-15: Scene 14

“Like every other gene, the Huntington gene contains many small sections called codons, each made of DNA. You can think of it like a chain: the entire Huntington gene is like a long chain and each codon is like a different link in the chain. In people who do not get Huntington’s disease, there are 35 or fewer identical links in a key part of the chain. But in people who do get Huntington’s disease, there are 40 or more of these identical links in the key part. Huntington’s disease results from having too many identical codons in the key part of the Huntington gene.”

Fig AC-16: Scene 15

“So the chain is too long?” asked Bryan. “Does it take up too much space or something?”

The doctor replied, “Well, not exactly. The system works like this: each gene makes another chemical called a protein and proteins are the things that do much of the work in cells. The Huntington gene makes a protein that we call huntingtin. In people who do not get Huntington’s disease, the huntingtin protein comes from a version of the Huntington gene with 35 or fewer identical codons in the key part. This huntingtin protein is able to do its normal work in cells. But in people who do get Huntington’s disease, the huntingtin protein comes from a version of the Huntington gene with 40 or more identical codons in the key part. This causes the huntingtin protein to have a different shape than normal and because of this altered shape, the protein cannot do its normal job.”

Fig AC-17: Scene 16

“After enough time, huntingtin proteins with the altered shape form into clumps or aggregations down inside cells, and we think these clumps clog up cells. We also think that the huntingtin proteins in these clumps may grab onto other proteins and keep them from doing their jobs in cells. So, these altered huntingtin proteins create a big problem, especially for nerve cells in the basal ganglia regions of the brain.”

Scenes 17-20^

Fig AC-18: Scene 17

“Eventually, these altered huntingtin proteins cause enough damage that the nerve cells containing the clumps begin to die. When enough nerve cells die in the basal ganglia regions of the brain, people start to have problems doing the movements that they always did before. This can be followed by changes in the person’s personality. For instance, the person might become more sad at times or more grouchy.”

Fig AC-19: Scene 18

After the doctor finished, Bryan’s dad asked, “So do I definitely have this disease?”

The doctor replied, “I don’t know for sure because your attitude changes and problems with moving could be caused by something other than Huntington’s disease. But since you said that your mother had Huntington’s disease, this means that there is a 50% chance that you might have it as well, just like a flip of a coin.”

In order to see for sure if Bryan’s dad had Huntington’s disease or not, the doctor suggested that Bryan’s dad go to a genetic testing center where he could give some of his blood to have it tested for the disease. Bryan’s dad went the next week.

Fig AC-20: Scene 19

At the dinner table one night, Bryan’s dad told him that the results of the test had come back from the genetic testing center. He said, “Bryan, I don’t know how to tell you this, but the test that I took showed that I do have Huntington’s disease. That is the reason I have been acting so strangely.”

Bryan could tell that his parents were upset, but they were trying hard to be brave about this news. As his dad finished talking, Bryan saw that his mom was beginning to cry. Bryan was not used to seeing his mom cry. He was also scared to hear that his dad had Huntington’s disease. Bryan felt overwhelmed and this made him cry too.

Fig AC-21: Scene 20

Later that night when Bryan was going to bed, his parents came into his bedroom to tuck him in. Bryan’s dad said, “You know Bryan, this disease may cause a lot of changes in my behavior from now on. The doctor even says that these changes will get worse over time.”

Bryan’s mom added, “But even though some things your dad does might start to change, he will never stop loving you. We both love you very, very much and nothing about this disease is going to change that. There may be a lot of challenges for us in the future, but the most important thing is that we keep a positive attitude and keep loving each other.”

Although Bryan still felt a little sad, these words from his parents made him feel much better. “Keep a positive attitude and keep loving each other,” Bryan repeated to himself.

Scenes 21-23^

Fig AC-22: Scene 21

The next week at school, Bryan’s dad came to pick him up and Bryan’s friend Joe said, “Your dad walks funny!” This time Bryan knew the reason why his dad walked differently. He was no longer angry at his dad. He wasn’t even angry at Joe. He realized that it was not his dad’s fault for changing; it was the Huntington’s disease that was making his dad act differently from before. Bryan knew that it would be hard for his friends to understand why his dad was acting differently, because they did not know the things that he had learned about Huntington’s disease. Maybe someday he could teach them about the huntingtin protein and nerve cells, so that they would understand too. But for now, his main focus was to keep a positive attitude and not allow these comments to hurt him. He knew that he would be much happier this way.

“Yeah,” said Bryan, “My dad has a medical problem. But he’s a real sport about it, and I’m learning to be a sport about it too. We walk and run less these days, but we still have fun together doing new things.”

Fig AC-23: Scene 22

On the ride home, Bryan’s dad said, “Hey Bryan, I know I don’t throw the baseball as well as I used to, but I can sure catch fish. I was thinking that this weekend we could go down to lake and go fishing.”

“That sounds great, Dad!” Bryan said. He loved to go fishing, but he was even more excited by the chance to hang out with his dad.

Fig AC-24: Scene 23

Bryan and his dad were wonderful fishermen! They both reeled in six fish! As they were getting ready to go, Bryan’s dad said, “Wow Bryan, this has been a blast! Thank you so much for coming out here with me.”

Bryan quickly replied, “No Dad, thank you!”

Bryan realized that although his dad was changing and could no longer do some of the things he had done before, they could still do plenty of other fun things together. He knew that his dad’s Huntington’s disease would present tough problems in the future, but he loved his dad and he knew that his dad loved him. No matter what the future had in store, nothing could ever change that.

Credits / Acknowledgements / Feedback^

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-M. Stenerson & S. Fu, 3-09-04

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Bryan's Dad has Huntington's Disease

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-M. Stenerson & S. Fu, 3-09-04

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HOPES Crossword Puzzle

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-M. Stenerson & S. Fu, 10-09-04
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HOPES Word Search

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