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You can start now. Ok. Ok. Hi, I'm Nikita. I'm a second year medic and I'm gonna, um, talking about genetics, I'm gonna be talking about um, the 33 of the lectures. So I thought we'd start off by going through some exam. So questions just to see like what your base of knowledge is. So this one's an SBA. So if you just put the answer in the chat, so which of the following is not a mechanism of how an autosomal dominant disease works. So a gain of function. B haploinsufficiency C dominant, negative or D loss of function. Mm, I'll give you guys a couple of seconds. Yeah. It looks like you guys are mostly getting, getting the answer. So, yeah, D is not a mechanism of how an autosomal dominant and disease works. So that's just um like an exam technique to just read it. And if it says not a mechanism, make sure you pay attention to that bit. OK. And then I got one more. So which of the following types of chromosomes are most commonly involved in Robertsonian translocation. A acrocentric B metacentric C submetacentric or D sub centric. Just again, put your arms in the chat. Um Yeah, so it is a, um, don't worry if you don't know uh fully why, um I'll cover this later. OK. So this is A vs AQ. What can cause the presence of two or more populations of cells with different genotypes in an, in individual? So remember for a VA vs AQ, it has to be four hours or less. Give me like 20 seconds maybe. Mhm. OK. Even if you don't have OK, anyone else um any other ounces. OK. So this process is mo mosaicism that could because it's the question is what can cause it, it isn't asking you to name what that phenomenon is. So M mosaicism is caused by X inactivation or non disjunction. If that makes sense, I'll cover it later. There's a slide about that. OK? And so now we're gonna start off with modes of inheritance and if you guys have any questions at any point, just put them in the chat and I'll um try not to them as best as I can. So for modes of inheritance, so what are the different types of genetic disorder inheritance patterns? There are six different types um that your lectures have covered um If you just wanna put it in the chat, what you guys think the six different types are? Yeah. Even just one or two. Yeah. Autosomal recessive, autosomal dominant. Yeah, X linked Y linked, mitochondrial. Yup. Those are all right. OK. So it's autosomal dominant, autosomal recessive X linked, recessive X linked, dominant wi linked and mitochondrial inherited. So now I'm just gonna go through um some of the key features of each of them. Um OK. So, autosomal dominant. So this is a uh inheritance pattern which involves non sex chromosomes and a trait is dominant if it appears in heterozygotes. So this means they only have to have one mutated allele to display the phenotype. And an example of this is eye color. So the oc two gene controls melanin production in melanocytes. And if there's an active gene and if you only have one, if you only have one dominant allele, you'll have melanin produced. And so you have brown eyes. But if you don't have any of the alleles, you have an inactive gene. So there's no melanin and so you have blue eyes. So the key features are that it affects males and females equally and it will also affect multiple generations. So if you can see the uh pedigree chart, so the red is effective and it has a vertical pedigree chart. So it affects people of all generations. So this is the mechanisms which are from the SBA from earlier. So it can either be gain of function. So the protein has a new function, so dominant negative, so that the mutated protein disrupts normal function. So it can't work properly. So this can either be like if it's folded improperly, it changes the target site for an enzyme to work on it. For example, or it doesn't fit through, it doesn't um bind to a transporter and then you have haploinsufficiency. So if you have one copy lost, then the remaining copy is insufficient to produce enough of the protein. And so an example of this is Huntington disease and this is caused by C A which a glutamine um is the amino acid that is produced by CDNA bases repeat expansion in the Huntington gene. So this leads to toxic protein aggregates in the neurons which lead to cell death. Yeah. So that's autosomal dominant. And then autosomal recessive is when you have need to have two copies of the abnormal gene um for the disease to show in the phenotype. So carriers uh when they have only one mutated gene but remain unaffected. So, for example, if the um mutated gene was big H and the normal gene was if the mutated gene was small, H and the regular gene was big H A carry would be big. Hh. And then the key features of autosomal recessive is that they are typically.