Pedigree analysis | How to solve pedigree problems?

[Music] welcome back friends welcome to another video tutorial from Samos Balaji and I've been receiving this request for a long time that to simplify pedigree analysis problems I have already put a lot of videos regarding pedigree and the detailed process of analyzing a pedigree and writing down the genotypes by looking at the pedigree but this video is all about how to solve pedigree problems really really fast just looking at the pedigree and you want to solve the problems and actually pedigree problems are everywhere in any type of exam you want to go from genetics you will get at least one pedigree so I am NOT going to talk about what is pedigree and how it works I am simply going to tell you what are the types of pattern or inheritance that are possible that can be explained with a pedigree and also tell you how to depict those things by looking at a pedigree so let's begin with it so first of all in human pedigree by looking at a pedigree and analyzing a pedigree we can tell that a disease can have four separate modes right mainly two major modes that can be a dominant or a recessive and among dominant we have autosomal dominant and x-linked dominant similarly in recessive we have autosomal recessive and sex linked recessive or x-linked recessive so there are four modes of a disease that can occur one way is autosomal dominant that means the disease gene is presenting the AutoZone and the trait is dominant autosomal recessive that the disease-causing gene is present again in autism but the expression is recessive that means it skipped generation x-linked dominant the disease-causing gene is present in X chromosome but it's dominant in nature in terms of expression and it's linked recessive that is a gene that is present also in the X chromosome but the expression is recessive now among this four we need to talk about some important features and properties of all these four types of way of pedigree and mode of disease transfer because here we are not going to solve the pedigree from start to the end we are just going to look for some clues whenever we find the clue we can tag a pedigree with any of this four type of feature so let's look at some important property of autosomal dominant first of all autosomal dominant is a dominant trait you generally don't skip any generation that means in every single generation at least one individual is affected and the second is both the parents can be affected but their child can be unaffected so think about it father and mother both are affected but the children are affected this is a high clue and very high link Lou in terms of autosomal dominant trait so whenever you find that thing you know it's a very much dominant trait and kind of carried by autosome so example of autosomal dominant trait is Huntington's disease and achondroplasia in achondroplasia is a type of dwarfism now let's move on to the second type autosomal recessive the property of autosomal recessive as it is a recessive trait that skips generation that means you won't find that in every single generation at least one individual effector you won't find that which is truth for our two formal dominant that means one of the individual is affected in generation 1 in generation 2 nobody is affected but again in generation 3 someone is affected this general keeping of generation is a type of recessive trait but how to know is is autosomal or non unaffected parents can also have affected children that father and mother both are normal without the causative agent of the disease but the children can be affected that is an important feature of autosomal recessive now we'll go for the third one that is x-linked dominant an x-linked dominant the disorder or the disease never transfer from father to son it always tend to transfer from father to daughter and mother to son but another very important thing and very interesting thing about the x-linked dominant trait is that if a father is affected that all the daughter of that father will be affected and this is a damn true thing which we are going to see in the next time when we are going to solve some pedigree and example for x-linked dominant vitamin D resistant rickets now explain recessive male are more affected compared to females and the reason behind this is males have only one X and that X is transferred from the mother because the father only gives a boy a Y so this disease also transfers from father to daughter and mother to son and the disease never transfer from father to son it's not possible because the father only provides Y to son right and it's an x-linked trait it's not possibility so these are all the important clues and feature that we want to find in all the pedigree problems that we are going to solve and let's look at some pedigree problems try to solve them only with these important formula and tips that we've talked about so let's move on and move to the first pedigree of our choice here we go the first pedigree of our choice as you can see in the basic idea of pedigree that the field region means those individuals are affected blank means the individuals unaffected unharmed so in this case in this pedigree what we can see like for every pedigree when you start to solve first you for whether it's an autosomal or a clade or Lou Perez is a dominant and recessive whichever clue you will get first now here you can see that this rate is present throughout and what else we can see is that if father and mother both are affected not father mother affected son affected daughter affected but this son is unaffected what does that signify both the parents are affected but child is unaffected and the only way is possible if it's an autosomal dominant pedigree even the first formula that we talked the first property that we talked so this particular set is going to tell us that this is going to be an autosomal dominant otherwise there won't pain also now I'll try to think about another formula like if parents are affected the disease is transferred its present in generations but in this this particular generation the disease is not present because that particular trait is not present in either of this two individual of the two separate generations because here you can see these are two separate suddenly and at this point this is a completely new family tree that is going to be created and in this case father and mother both are unaffected that's why the child children are unaffected but other than that this particular clue is enough to give you an idea that this is autosomal dominant pedigree so see how easy it is to solve with those formula let's move on to the next type this is the second pedigree that we want to solve so let's check it try to pause this video here and try to apply those tips and to get an answer then we will talk about it now let's look at here in this particular pedigree what we can see is that this is the generation of all the generations we can easily see him people are affected but the most important part interesting part about this pedigree is this region if you look at this two generation what you can find is that mother and father both are unaffected but they have one affected daughter so parents unaffected child affected the only way it's possible if it's a autosomal recessive trait so another clue about recessive because here in this generation there is no disease but now this is again coming back so it's keeping generations so obviously it's discussing and also you can see that name and female are almost equally affected it's not like males are more affected so we are kind of confirmed that this pedigree is autosomal recessive pedigree without any doubt let's move on to the third one this is the third pedigree that we want to solve so what you can again see in this pedigree which is unique if you look at this pedigree male and female both are affected so you cannot just exclude the idea whether it's an autosomal onyx link what else you can look for you can look at here that almost the distribution pattern is really is not going to apply that parents are affected child unaffected those laws are not applicable in this pedigree they've checked it but there is something new about this pedigree there's something unique about this pedigree and for all this pedigrees expert talking about I want you to find that unique feature about the critically because whenever you find that unique feature you know the answer so look at here in this pedigree even in the first two generations here we see the father is affected and all the daughters are affected that is something unique here you can see father is affected daughter is affected here is only one daughter so on daughter is affected a three daughters three daughters all of them are affected because the father is affected so what kind of pedigree provides this information if a father is affected then all the daughter will be affected and it will not transfer in any region from father to son not possible look at here the son is affected but the trait is there from mother never from the father similarly your son is affected the tre transferred from mother so in this pedigree there are two clues one affected father provides it all the daughters to be affected and in neither of the swings no place in this pedigree transfers between father to son that signifies that this pedigree is an x-linked dominant pedigree you can check the first slide that we discussed this is a typical feature of x-linked dominant pedigree so now let's move on to the fourth type and in this case what we can see is this is another type of pedigree and you can also see that the individuals of in different regions so how you are going to solve this one by looking at this pedigree you need to find out whichever part of this pedigree is going to give you that clue about the formula that we discussed and now by looking at this pedigree I can see it clearly here in these two generations because if you look at here in this first generation second generation actually overall here father and mother unaffected but one of the son affected so parents unaffected and an offspring is affected that is a typical part of a recessive pedigree apart from that what else we can see is that this is recessive so it can be autosomal recessive or x-linked recessive you know how to prove whether it's an autosomal or x-linked another thing that you can check here is the disease is mostly transferred from mother to son here from mother to son in this particular case father is completely unaffected so obviously the disease should be transferred from mother to son and it's not being transferred from mother to daughter generally in this case we see the disease is transferred to daughter but here the father is also affected so what does that mean generally your disease is keeping generations for assessing I'm only affecting males and affected males are generally getting this from the mother so mostly this disease is going to be x-linked recessive disease so by looking at this pedigree you can say now yes it is an x-linked recessive disease and that's how the disease-causing gene is transferred from one generation to the other now till this point we talked about all these four types of pedigree and we checked one example of all these four types and you see simply in most of this pedigree you can simply apply that knowledge apply that formula and you can get an answer almost instantly without thinking of too much or without feeling what genotype all those different regions have so if you have those pedigree and you can get some of the features so obvious by looking at the pedigree you simply can this rule to get an answer within even minutes you don't need even minute to complete analyzing a pedigree and that will be always beneficial but in some cases the pedigree can be a little complicated where you can't probably apply most of the rules that we discussed in those case you try to get a guess an idea about the pedigree utilizing those formula and then try to think about the genotypes a little bit to answer it but I believe if you know those formula and if I apply each of those formula by looking at a pedigree finding the unique feature of that pedigree and applying the exact formula you are going to get an answer within 30 to 40 seconds that will save a lot of your time and hope this video helps you out if you like this video please click the like button share this video with your friends and subscribe to my channel to get more and more videos like that and also mention me about the new way of teaching using led if you like this I am going to continue with this method for any e.t video lectures which I am going to prepare very soon thank you

Channel: Shomu's Biology

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Keywords: suman bhattacharjee, shomus biology, Pedigree analysis, pedigree analysis practice, pedigree analysis genetics, pedigree analysis probability, pedigree analysis answers, pedigree, pedigree charts, genetics, How to solve pedigree problems, solve pedigree problems, solving pedigree problems, pedigree problems and solutions, how to analyze pedigree, analyzing pedigree, genetics problems

Id: bL4JV5Z2jsc

Length: 14min 23sec (863 seconds)

Published: Wed May 03 2017