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USMLE Step 1 Linkage Disequilibrium

Everything you need to know about linkage disequilibrium for the USMLE Step 1. You will learn about alleles, chromosome loci (plural for locus), and how gene proximity can make all the difference.
Stress less. Study smarter. Crush Step 1.
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Пікірлер: 107

  • @madryden5
    @madryden55 жыл бұрын

    You've made a frustrating question much more understandable - thank you.

  • @physeo-USMLE

    @physeo-USMLE

    5 жыл бұрын

    We're glad it helped! 🙌

  • @arushiarora706
    @arushiarora7065 жыл бұрын

    Awesome explaination. It deserves to be shared to maximum people

  • @physeo-USMLE

    @physeo-USMLE

    5 жыл бұрын

    We're glad you like it! Don't forget to tell your friends and classmates!

  • @dantitoprrito
    @dantitoprrito3 жыл бұрын

    Oh man, this is the best video out there. I have been reading the same 3 pages of the book for at least 2 hours and I couldn't understand a thing. I watch your 7 min video and now it's all clear. Thank you so much!

  • @yashashwineerai4112
    @yashashwineerai41124 жыл бұрын

    That was an amazingly clear explanation for a topic I got stuck at understanding from papers! Thank you!

  • @burns1606
    @burns16063 жыл бұрын

    finally someone explains and I could understand linkage disequilibrium thank you!!

  • @fabianfloresrivero6855
    @fabianfloresrivero6855 Жыл бұрын

    I am very grateful for your explanation. I spent all day trying to understand this and it was made very easy with your video. Really thank you very much!

  • @thankyou6555
    @thankyou65552 жыл бұрын

    I must say this is an outstanding explanation! Thank you.

  • @anjubiswas6815
    @anjubiswas68152 жыл бұрын

    Thanks a ton!!! I was looking for this clarification for a long time. Finally, I found it! Thank you for making the video.

  • @michaelfaraday8391
    @michaelfaraday83913 жыл бұрын

    My first time commenting on an academic video. I simply say thank you!!!

  • @dinelkananayakkara3317
    @dinelkananayakkara33172 жыл бұрын

    Awesome video! So intuitive and helpful. Thank you!

  • @gideonokyeremensah6647
    @gideonokyeremensah66473 жыл бұрын

    The explanation given in this video is great. Thank you very much.

  • @tal1989
    @tal1989 Жыл бұрын

    sublime explanation, was really struggling with this when it came up in the extended phenotype

  • @nina-cr5pe
    @nina-cr5pe3 жыл бұрын

    i rewatched this part of my lecture 5 times and still didn't get it, with this video i understood within 3 minutes. thank you!

  • @lerazurig
    @lerazurig4 жыл бұрын

    Great explanation! It was super helpful. Thanks!

  • @nikolaoslinaroudis215
    @nikolaoslinaroudis2155 жыл бұрын

    Very nice and clean explanation,thanks a lot!

  • @qasimhashmi7512
    @qasimhashmi75125 жыл бұрын

    amazing man (y) i was so confused with this thing. Cheers :)

  • @CamilaLuizaDelaix
    @CamilaLuizaDelaix4 жыл бұрын

    i can't believe is THIS easy! thank you!

  • @janiranavarro
    @janiranavarro3 жыл бұрын

    It makes total sense now! Thank you!

  • @krishnendukundu6446
    @krishnendukundu64464 жыл бұрын

    This vdo help me a lot.. thank u for clearing my concept

  • @gizemkok7954
    @gizemkok79542 жыл бұрын

    Amazing description! Thank you!

  • @swatijain2223
    @swatijain22233 жыл бұрын

    Wowww, you explain this difficult concept in very easy manner so big thank you to make this video and helps student to understand genetics.

  • @ellora5535
    @ellora55352 жыл бұрын

    Thank you this was the best explanation of all the vedios i watched

  • @wernerdykstra7021
    @wernerdykstra70214 жыл бұрын

    Thanks! I finally get it!

  • @JTCC20
    @JTCC20 Жыл бұрын

    sweet, clear and concise. Good video!

  • @dc33333
    @dc333334 жыл бұрын

    excellent speaker!!! Thank You

  • @yea2100
    @yea21003 жыл бұрын

    This helped me so much ! Thank you.

  • @sumanshisingh3127
    @sumanshisingh31274 жыл бұрын

    Perfect and succinct! Thank you :)

  • @IbironkeOtusile
    @IbironkeOtusile3 жыл бұрын

    God bless you for this! 🙏🏾

  • @FreeDay997
    @FreeDay9974 жыл бұрын

    You man are a genius, never understood it in the lecture, but now I do, thx!

  • @physeo-USMLE

    @physeo-USMLE

    4 жыл бұрын

    🙌

  • @andreeanicoletacrintea3089
    @andreeanicoletacrintea30893 жыл бұрын

    This was an amazing simple explanation. Are there any videos in which we could have a clear view on how LD is important in GWAS and provide a clear understanding on how to interpret the haplotype blocks? Many thanks!

  • @grace8694
    @grace86943 жыл бұрын

    you are a life saver!!! omg!! thank you 😩

  • @starsadmirer1724
    @starsadmirer17244 жыл бұрын

    thank you so much, very informative and helpful♥

  • @alpr1864
    @alpr18644 жыл бұрын

    That is good to have a great explanation of what its explanation is hard to explain. :))))

  • @ajayhemanth
    @ajayhemanth4 жыл бұрын

    Brilliant Explanation Mate !!!

  • @afsana3505
    @afsana35052 жыл бұрын

    Wow it's just fantastic vedio now i got this concept .Thank u so much sir

  • @bann9437
    @bann94377 ай бұрын

    thank you sooo much, i finally understand this !!!!!!!!!

  • @ccdj35
    @ccdj353 жыл бұрын

    Great explanation, thanks.

  • @chandrikarajpurohit8856
    @chandrikarajpurohit88564 жыл бұрын

    Awesome sir.....too good

  • @azz9007
    @azz90073 жыл бұрын

    i love this. so clear

  • @ishanibose4351
    @ishanibose43514 жыл бұрын

    Thank you. This is very helpful :))

  • @mostafanabil2005
    @mostafanabil20055 жыл бұрын

    It is now crystal clear,thank you

  • @normadicn5700
    @normadicn57004 жыл бұрын

    So Linkage Analysis involves the analysis of basically linkage of Chromosomes during division. Now first each set of Chr should be heterozygous for each trait at a foci. Under Linkage analysis you can observe Linkage equilibrium which means the Alleles on the SAME Chromosome would still have characteristics of Independent Assortment as long as they are far away. Linkage disequilibrium means when the frequency of a combination occuring is higher than that which we would get by chance. That's what i learnt

  • @KendallKnaus
    @KendallKnaus Жыл бұрын

    Thank you- wonderful cleat explanation-

  • @anthonykerbage
    @anthonykerbage4 жыл бұрын

    Thank you this is awesome!

  • @physeo-USMLE

    @physeo-USMLE

    4 жыл бұрын

    🙌

  • @Astute_Classes
    @Astute_Classes Жыл бұрын

    Absolutely fantastic

  • @justiniancruz6314
    @justiniancruz63145 жыл бұрын

    Brilliant!!! Thankyou so much

  • @physeo-USMLE

    @physeo-USMLE

    5 жыл бұрын

    🙌

  • @belaliamelouka9613
    @belaliamelouka9613 Жыл бұрын

    Thank you so much sir Allah bless you 💙

  • @muhannadak8087
    @muhannadak80874 жыл бұрын

    Thank you sooooooooooo muuch.

  • @zhassulanzhaniyazov3830
    @zhassulanzhaniyazov38305 жыл бұрын

    Very good explanation, really liked it.

  • @physeo-USMLE

    @physeo-USMLE

    5 жыл бұрын

    🙌❤

  • @kristenhale3022
    @kristenhale30224 жыл бұрын

    thank you!

  • @xElinnee
    @xElinnee4 жыл бұрын

    thank you lord

  • @sheikhahmad6178
    @sheikhahmad6178 Жыл бұрын

    Thanku so much❤️💖

  • @jared394
    @jared394 Жыл бұрын

    amazing explanation

  • @akashsalaria9683
    @akashsalaria96834 жыл бұрын

    Just amazing

  • @zainabqaysar4668
    @zainabqaysar46684 жыл бұрын

    Bless you

  • @birenchaudhary7637
    @birenchaudhary76373 жыл бұрын

    Thank you. And Wouldn't it be also called linkage equilibrium if two alleles are on the separate chromosome? UW has given example of equilibrium as on seprate chromosome.

  • @dywu12
    @dywu123 жыл бұрын

    quick question: do the chromosomes "break" twice (I mean on two places) when linkage disquilibrium occurs? The two pictures showing Ab and aB für LD suggests this, or could it also be that there is a small "blue A part" and a much bigger "pink b part"? thx

  • @NikhilRatnaNeuro
    @NikhilRatnaNeuro4 жыл бұрын

    Highly appreciate the attempt. I think I have a legit question. 1)If the alleles are far apart, they behave as if they are on diff chromosomes, and recombine the maximum, giving rise to 0.25:0.25:0.25:0.25 frequencies for the 4 combinations (AB,Ab,Ba,ab). 2) if they are very proximate to each other they are almost 100% linked which gives us increased rate of AB, ab, max of 0.5. 3) If their distance is neither far nor too close, then recombination can happen few times and ratios of AB, ab will be less than 0.5 but more than 0.25. case 1 is linkage equilibrium . case 2 and 3 are disequilibriums (in both cases the frequency is more than the case 1. what is the scenario that the frequency could be less than 0.25? Now the linkage disequilibrium definition says, it could more or less often than expected by chance alone (randomness). how can it be less often 0.25? by the time I typed the above, I realised it could be new mutation incidence.. am I right? or missing something?

  • @carmineceraolo5610

    @carmineceraolo5610

    4 жыл бұрын

    I just tried to think about something that could make cause the frequencies to be less than 0.25. The only thing that comes up to my mind is chromatin structure. If two genes are divided by a region rich in euchromatin than I think it is more likely for crossing-over to occur in that region. This could possibly make conservation (i.e co-occurence) of the two genes less likely than 0.25. Is it clear? What do you think about it?

  • @CsprsSassyHrly

    @CsprsSassyHrly

    4 жыл бұрын

    Maybe selfish elements that suppress one allele over the other? Or rapid population expansion that introduce new variants into the population?

  • @soumitrashome1642
    @soumitrashome16423 жыл бұрын

    Awesome. Wow

  • @dessertisland2491
    @dessertisland24914 жыл бұрын

    Great video, I finally understood the whole thing! Thank you so much! I was wondering - you keep saying that this or that occurs whenever "two allels" are close or far apart on a chromosome. Wouldn´t it be more correct to say that "two genes" are close or far apart?

  • @physeo-USMLE

    @physeo-USMLE

    4 жыл бұрын

    Hey! You are right that they could also be referred to as genes. That said, they can also be referred to as alleles too, because the diagram is showing 2 genes and 4 alleles. To keep it simple, we were referring to each letter as an allele. The letter "A" and "a" are the same gene, but different alleles, while "A" and "B" are different genes, however, "A" and "B" are also considered different alleles for a different gene. Hopefully that provides some clarity!

  • @ajithamohan6956
    @ajithamohan69564 жыл бұрын

    Based on allele frequency, whether, We can calculate haplotype frequency??

  • @bounaimwanissa9708
    @bounaimwanissa97083 жыл бұрын

    omg im gonna cry i finally understand it

  • @romanaahmadmir4417
    @romanaahmadmir44175 жыл бұрын

    Thank you !!

  • @physeo-USMLE

    @physeo-USMLE

    5 жыл бұрын

    🙌

  • @ASAR0711
    @ASAR07114 жыл бұрын

    thankyou

  • @yasmeennasr637
    @yasmeennasr6373 жыл бұрын

    Thankyou

  • @jungyoonyang6233
    @jungyoonyang62334 жыл бұрын

    how come When you are explaining independent assortment; same alphabet means same type of gene/ lower or capital distinguishes the allele but for the linkage equilibrium; you mentioned that 'A and B are the different allele' as if they are the same gene

  • @abdulrazakalmarashli367
    @abdulrazakalmarashli3674 жыл бұрын

    You are awesome!

  • @physeo-USMLE

    @physeo-USMLE

    4 жыл бұрын

    🙌

  • @YamaKabiri-py3zv
    @YamaKabiri-py3zvАй бұрын

    Greatest

  • @meadhikari
    @meadhikari3 жыл бұрын

    excellent

  • @mustafaanlylmaz7258
    @mustafaanlylmaz72582 жыл бұрын

    enlightining

  • @Happy.Traveller
    @Happy.Traveller3 жыл бұрын

    Hi, I'm still confused and I wonder if you can help. The example at 2:44 says that allele A occurs 50% of the time and the other 50% of the time, allele B occurs, "what is the chance of having A AND B". If we pretend A is brown hair and B is brown eyes, what the example is saying is (at least the way I understand it) half the people have brown eyes and half the people have brown hair. This statement is a problem since having a certain hair color doesn't automatically decide the eye color. Saying half the people have brown hair (A) doesn't tell you their eye color, and saying half the people have brown eyes also don't tell you their hair color. No matter what hair color they have, they must also have an eye color and vice versa. Therefore the question about AB makes no sense to me. Should it not therefore be "Big A dominant brown hair occurs 50% of the time and little a recessive blond hair occurs 50% of the time, what is the expected frequency of getting Aa?" (and since A is dominant while a is recessive, the phenotype would be brown hair)? Also linkage [dis]equilibrium is counterintuitive to me: if 'linkage' means "on the same chromosome" and 'equilibrium' means "constant or same": then if 2 alleles are close together like at 6:09, then they are more likely to be inherited together since there are less chances of them being separated while undergoing recombination. Since they are more likely to be"constantly" inherited together, I'd assume this means they are at linkage equilibrium.

  • @camilanicole3254
    @camilanicole3254 Жыл бұрын

    Legend

  • @azz9007
    @azz90073 жыл бұрын

    i have a question, that percentages were based on population right? for example in linkage disequillibrium, 49% of population tested, will have AB spermatid, and then just 1% of population will have aB... am i right?

  • @LiamDurkin-kf2rr
    @LiamDurkin-kf2rr11 ай бұрын

    make a playlist fpr genetics

  • @spiceup4100
    @spiceup41003 жыл бұрын

    I have subscribed you...

  • @rizapaolahawkeye
    @rizapaolahawkeye4 жыл бұрын

    So, the linkage disequilibrium is the reason for distorted segregation ????

  • @chrish7805
    @chrish78054 жыл бұрын

    At (1:42 seconds) you say that A's represent a gene (with big A being one allele and little a being another allele of that gene) and B's represent another gene (again with its corresponding alleles). But then later in the video you use A and B to represents alleles (3:40 seconds). Not sure if i'm the only one that saw this or if I am missing something but it confused me a bit. So from my understanding when talking about linkage we are talking about two genes and how they are inherited. With linkage disequilibirum we have the alleles for two different genes in close enough proximity that they are essentially inherited together the vast majority of the time and do not follow the typical independent assortment (where the inheritance of two genes are independent of each other). Is this correct? Thanks in advance!

  • @mdmonoarhossain8616

    @mdmonoarhossain8616

    Күн бұрын

    I do agree with you. This question comes to my mind also. Actually those two alleles are the allele of two different genes.

  • @paulaolivellaanido6157
    @paulaolivellaanido61573 жыл бұрын

    In minute 1:41 he says that A represents a gene, and B represents another gene, but then when talking about linkage equilibrium A and B are referred to as aleles. I'm not sure I'm understanding correctly the difference between the two.

  • @nats379
    @nats3795 жыл бұрын

    What is the reference used for this video? Thanks!

  • @physeo-USMLE

    @physeo-USMLE

    5 жыл бұрын

    Hey! We referenced a whole bunch of different sources to bring this all together so that it would be as cohesive and seamless as possible. We hope you like it!

  • @kakashibnl7984
    @kakashibnl79843 жыл бұрын

    I'd ve loved if you spoke just a liiiil bit slower haha (non native eng speaker ^) ,, still helped me a ton tyvm

  • @pointeprincess302
    @pointeprincess3024 жыл бұрын

    Thank you so much for this. I hate genetics lol

  • @Pierre.parisot97
    @Pierre.parisot974 жыл бұрын

    I don't understand why there are 4 chromatids in the beginning and 2 chromatids when you explain linkage equilibrium?

  • @CsprsSassyHrly

    @CsprsSassyHrly

    4 жыл бұрын

    If I'm right, I think he's trying to say the alleles are more likely to be in linkage disequilibrium when they're on the same chromosome, whereas if they're on different chromosomes, they're going to be in linkage equilibrium. However, I do believe that LD can occur even if alleles are on different chromosomes.

  • @pickaxingoneuropa8457
    @pickaxingoneuropa84572 жыл бұрын

    Linkage Disequilibrium is Linkage KISSequilibrium- the alleles are toooooooo close! ya Feel me saaaaaawn?! Mnemonics for life. Live the Dream. (Terms and Conditions apply, dreams aren't for everyone, mnemonics may cause tooth decay, and headaches, Tom Cruise tried to eat his baby's placenta, hashtage kisseekisseedisseedissee)

  • @fires146
    @fires1465 жыл бұрын

    When you state that “linkage equilibrium refers to alleles that are found on the same chromosome” don’t you actually mean genes?

  • @physeo-USMLE

    @physeo-USMLE

    5 жыл бұрын

    Hey! You are right that they could also be referred to as genes. That said, they can also be referred to as alleles too, because the diagram is showing 2 genes and 4 alleles. To keep it simple, we were referring to each letter as an allele. The letter "A" and "a" are the same gene, but different alleles, while "A" and "B" are different genes, however, "A" and "B" are also considered different alleles for a different gene. Hopefully that provides some clarity!

  • @NikhilRatnaNeuro

    @NikhilRatnaNeuro

    4 жыл бұрын

    @@physeo-USMLE good explanation. So what are we referring to here when we call allelic frequency, essentially of 2 diff genes? where as when in the context of Hardy Weinberg law it is of same gene?

  • @tisaloewen7051
    @tisaloewen70513 жыл бұрын

    AH okay so: Linkage: 2 alleles on same chromosome regardless of the power of that bond....... when that link is weak and they can be swapped with another chromosome through crossover, that is link eq. ----- when that bone is strong because they are close and they are likely to stay together that is link DISeq. Finally! cool. ty.

  • @tayabsoomro
    @tayabsoomro2 жыл бұрын

    To be more accurate, 1:54 shouldn't you have said "because each of the GENES are on different chromosomes", instead of "...because each of the ALLELES are on different chromosomes"?

  • @69Arj69
    @69Arj695 жыл бұрын

    linkage disequilibrium starts at 5:15 !

  • @biauxchety8129

    @biauxchety8129

    5 жыл бұрын

    The Intro is Important

  • @normadicn5700

    @normadicn5700

    4 жыл бұрын

    Am glad he talked about Linkage equilibrium

  • @salmatarfaya3359
    @salmatarfaya3359 Жыл бұрын

    You've made a frustrating question much more understandable - thank you.

  • @lehuang1924
    @lehuang19244 жыл бұрын

    Thanks! I finally get it!