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Video transcript

cystic fibrosis is one of those names that doesn't really describe what the disease is when fibrosis is a lot of scarring insists we think of fluid-filled sacs and this does come into play in the pancreas as we'll see later but for now just think of cystic fibrosis or what we usually just say CF it's just the name for this disease and we'll find out step-by-step what it actually describes so first the cystic fibrosis is a genetic thing so it comes from our genes or it's encoded in our DNA I'm trying to draw the double helix of the DNA right now like that and we get this of course from our parents and humans have 46 pairs of these and four you get one from mom one from dad so cystic fibrosis is a recessive disease as opposed to dominate in very simple terms recessive and dominant is refer to how many copies of the defective gene do you need to have the disease so if we think of the CF gene is having two different variations for most people it's a normal gene let's use Big B that's normal and then for the gene with cystic fibrosis we have a little B remember that the little B carries the mutation for cystic fibrosis so if you can get one from mom one from dad out of these two there are three possible combinations right so we have Big B small B this one when we have Big B Big B or small and small for recessive diseases you have to have two copies of the defective genes so mom and dad must give you the CF gene for the disease to happen now this is different from dominant diseases where it only takes one copy of the defective gene let's do a quick genetic lesson here so if we have two people having kids and both of them carry the CF gene but they don't have it remember you need both copies of the little B to have it so they both have the little B but neither of them has the actual disease and it together get together and have kids so there are four different combinations between their two copies of genes so for this square we get Big B and Big B does this person have CF no they don't even have the CF gene at all for this person they carry the copy but just like their parents because they only have one copy they don't have the disease and same with trial number three before this last one you get small B and small B and this child has CF so for this particular combination is one in four so you can imagine the math gets a little more complicated depending on what the parents have all of this to say that cystic fibrosis is something that's passed on genetically and whether or not a person gets it depending on what their parents have for the CFG and the studies and the numbers show us that this disease is most common among the Caucasian population just because of the frequency of the small B the CF gene in this population since there's the highest frequency of CF genes within the Caucasian population traditionally they have been most affected by this disease so out of 3,000 people in the chalcogen population one person would have CF they would have this little B little B combination and for other races traditionally there's been less frequency of the disease because the gene is not as frequent for example in African people there's about 15,000 people and get one person with CF and in Asians there's about one in 30,000 now these numbers of course change all the time the point is that the more frequent a gene is in a population then there's more chances of you getting little bit little B so what is actually defective about the CF gene is it's Gina controls the transport of too little ions one is chloride it's chloride and the other one is sodium this is the chemical symbol for sodium okay with fierce really interesting because sodium chloride together that's table salt this will eat but these molecules are in our bodies and they do different things at different places the CF gene controls how they behave and this is the thing that's defective and as a result we get all these problems it's kind of like if you have machine made of tiny little cogs of all different shapes and sizes and I just held together and for the machine to work every piece should do their job there's one piece let's say this size that just keeps having problems so the same piece is in different parts of the machine with different jobs and when they're defective because genetically it's defective then every time you get to the CF gene something is wrong so the symptoms that we see are all over the body's not concentrated in one organ one of the most heavily affected organs and also the place where most CF patients have a lot of trouble is the lungs you might think how does chloride I have to do with the lungs why does it make such a big difference the thing is our lungs are lubricated by all this mucous chloride and sodium play a big part in how much mucus what's the concentration of it so when they are malfunctioning then the nature of the secretions change so instead of nice mucus that coats the lungs and lets it function normally we get these thick secretions that clog up the lungs but with that you get a lot of infections because it's almost impossible for them to clear all that mucus thick mucus out of their lungs and factor shifts to make matters worse that environment they have foster infections that we don't even commonly seen for example there's something called Pseudomonas and then Pseudomonas infection is very rare in a person without and healthy lung basically but in CF patients it's very prominent and it's harder to treat and also it's just hard to take a real good breath without that gunk in there so the o2 concentration might be low it says it's hard to cough up all that mucus your C CF patients have to wear this vest for maybe 30 minutes a day that's plug to a machine that just mechanically shakes out the mucus in their lungs this is a standard therapy for people with cystic fibrosis another big area that is a huge problem with cystic fibrosis is the digestive tract so we particularly in particular we have the pancreas and really just a GI system in general the pancreas is an organ that's tucked under the diaphragm there and its main job is to secrete all these things that help us digest our food the same thing with the thick secretions here so when it's all clogged up the things the enzymes are supposed to come out can come out so especially when these patients are children it's hard for them to get the nutrients they need to grow so even if they eat a good diet a lot of times they are malnourished because the nutrients don't get absorbed into their system now nourished in a similar way the liver which is on the opposite side of the stomach as the pancreas is secretes bile all this mucus again in the ducts and the bile can't get out and bile helps us emulsify the fats that we eat and digest it now the pancreas also gives us insulin insulin is the chemical that helps us regulate the blood sugar so with the lack of insulin a lot of times these patients have symptomatic diabetes definition of diabetes is not able to control your blood sugar right so if you don't have insulin it's like to have type 1 diabetes so with the malnourished men the diabetes the lack of digestive enzymes kids with CF often have trouble reaching their full stature so their growth is usually restricted so you can see one little gene that controls the transport of these two molecules I'm trying to show you that it goes to the lungs the pancreas everywhere in the body really and our treatments tend to revolve around how to control the symptoms of these problems there are symptoms in CF that's not really treated for example since sodium and chloride makes salt oftentimes their sweat and their skin just tastes more salty but that's not something that affects people's health so much so that's not treated as much the point is cystic fibrosis shows up in so many ways throughout the body and going back to the name why do we call it cystic fibrosis this is describing the scarring that occurs in the pancreas as a result of the disease you have these cysts and they have scarring from all the blockage and the damage to the tissue that leads to that's why I said cystic fibrosis not at descriptive of the disease but just remember that it's really a group of symptoms that all happened because of this recessive gene controlling sodium and chloride