00:01
In order to answer this question, let's talk about pedigris.
00:02
He says, what is the most likely mode of inheritance for each of the following pedigris? some of these pedigris represent more than one mode of inheritance, where there is more than one possibility, give reasons why you support or why you would support one mode of inheritance over the other one.
00:19
So remember that first you have to answer or to ask yourself if there is father to some transmission.
00:24
If you answer to this question, if there is father to some transmission, is no, then it means that this is an x -link disease.
00:35
Okay, so, and within this, if males are more affected than females, this is going to be ex -linked recessive.
00:42
But if you see that females are more affected than males, this is going to be an x -link dominant.
00:48
If your answer to fire to some transmission is yes, then it means that this is an autosomal disease.
00:55
And from this, if you see that there is vertical transmission, this is going to be an autosomal dominant but if it is or if you see a horizontal transmission this is going to be this is going to be a autosomal recessive okay so let's answer this question this first pedigree as you see here you see the disease only here and it's here and both of them are females it means practically females are the only ones that are affected and as you can see here you also see that there is like a mate between two family members or between two cousins in this case.
01:39
Also, as you can see here, these two people are affected, but they have healthy parents.
01:47
So it means that at least one of these parents are going to be, it's going to be covered for the disease.
01:52
So this can be theoretically it can be an x -linked recessive disease because if this is your mutant allele and this is your normal allele, then this is going to be, this woman can be a carrier and this man can be healthy.
02:10
If you do a panade square between this, you're going to get here, heterocygose, or actually no, actually it cannot be an x -linked and recessive.
02:24
Why? because in order for females to be affected by x -linked recessive diseases, they need two mutant x chromosomes like this.
02:35
So it means that one mutant x came from the mother, the mother can be covered so up to here it fits.
02:41
And the second mutant x chromosome can confront the father, but the father has only one x chromosome, so the father would be affected.
02:49
But this is not a case because according to this, this father is healthy.
02:53
So it does not fit for x -link recessive.
02:56
It is not an x -link dominant either because an x -ling dominant, cannot have caggers and apparently these parents from these two affected people are cagers.
03:08
So apparently this is a case of autosomal recessive disease because these two parents are heterocygose, it means caggers and the same for these parents here.
03:19
They are both heterocygous and when you have a close between two heterozygous people, you have here one quarter chances to get homozyglysis, it means that disease.
03:29
Okay, so this is the answer for the first pedigree.
03:32
Now let's hope for this second pedigree here.
03:37
First, as you can see here, only males are affected apparently, okay, and not women.
03:45
So this case is very likely to be a case of x -link excessive.
03:50
For example, as you can see here, there is no father -to -sson transmission.
03:54
Also here, you see that there is no father -to -sund transmission.
03:58
So there is there father -to -sund transmission, the answer is no, so this is going to be x -linked.
04:02
And as you can see, males are more affected than that there are not.
04:04
And females, so this is going to be excellent recessive.
04:08
Now, can it be autosomal recessive like this? and the answer is actually yes, because for example, if this is hetero cyboros and this is heterozygote, you're going to have 25%, as you saw here in the planet square that i did, a 25 % chance to get offspring with the disease.
04:26
And this is also going to fit here and also here.
04:30
Okay, but it is more likely to be an excellent recessive because as you can see here, only males are affected.
04:38
While in autosomal recessive diseases, males are equally affected as females.
04:42
So here you have a disease ex -linked recessive.
04:46
Now let's go for this third pedigree.
04:49
As you can see here, there is further to son transmission.
04:52
So first, this is not going to be ex -linked, and this is going to be an autosomal disease.
04:56
Now, you see that as this person here is affected by, but both parents are not affected.
05:04
It means that both parents are caggers for the disease, and carriers are only found in recessive disorders.
05:09
So this is going to be a case of autosomal recessive disease.
05:16
Okay, this is the only possibility here.
05:18
This is why here you have a cross between two homo -sia recessive and this is going to give that all 100 % chances to get offspring with the disease.
05:26
Let's go for a pedigree d.
05:30
As you can see here, there is also further to some transmission.
05:33
So this is not an excellent disease.
05:36
And why is happening? well, this is because remember that a person in her is one allele from the mother and a local leaf from the father.
05:44
In case of x -linked, or in case of the x chromosome, you have that this is the female and this is the male.
05:52
Okay? and one person inherits one allele from the mother and one from the father.
05:57
So if you're producing a song, then the song is going to be xy, right? okay.
06:02
So this y chromosome should come or can come from either the mother or the father.
06:06
But mothers don't have y chromosome.
06:09
So this y chromosome is going to be donated by the father.
06:12
It means that this x should come from the mother.
06:15
So either this or this x chromosome here.
06:18
So if you see, or for example, let's suppose that this father has a disease and they have a song.
06:25
So this song is not going to inherit the x -link disease from the father because fathers transmit the y chromosome to songs, not the x chromosomes.
06:33
Okay, so this is why you always have to ask.
06:36
Yourself about follectusal transmission.
06:39
So this is a case of autosomal because there is phallucon transmission.
06:42
And also as you can see here, you see a horizontal or i'm sorry, a vertical transmission.
06:48
Okay, practically the disease is shown in all the generations.
06:52
So this is a case of autosomal dominant.
06:56
And you may ask, and you may ask, so why here, between, a cross between two affected people in an autosomal dominant disease produces three healthy children and well, because both of them are heterocylus.
07:09
If both of them are hetero cycles, then you're going to have following...