Genetic Inheritance, Autosomal Dominant, X-linked Recessive, Mitochondrial Disease Polygenic mtDNA

www.stomponstep1.com/genetic-i...
Autosomal Dominant Inheritance is when one allele, on any chromosome other than X or Y, is expressed over another allele of the same gene. This allele determines the phenotype (observable characteristics) and is referred to as dominant. The allele that is does not affect the phenotype is referred to as recessive. The dominant allele is often given the capital letter for a character while the recessive allele is given the lower case. Therefore, a heterozygous individual who is a carrier for the recessive gene would be represented as Aa. Usually on a pedigree nearly every generation has an affected individual.
Autosomal Recessive Inheritance is basically the opposite of autosomal dominant. Recessive alleles only change the phenotype when there is no dominant allele present. Heterozygous individuals do not show the phenotype of the recessive allele, but can pass this allele on to their offspring. These heterozygous individuals are called carriers. Usually on a pedigree few individuals are affected.
X Linked Recessive Inheritance is a type of recessive inheritance for genes on the X chromosome. Males express the phenotype when they inherit 1 effected allele, while females need to inherit 2 effected alleles. This is because the gene lies on the X chromosome, and males only receive a single X while females receive 2. Males cannot pass the effected X allele onto sons, because a son must receive a Y from the father to be male. Males are affected far more often than females. Women are very rarely affected by these disorders, and are primarily heterozygous carriers when they have the gene.
Mitochondria have DNA (mtDNA) that is circular and separate from the chromosomes in the nucleus. Mitochondrial Inheritance is only through the mothers and the fathers mitochondrial DNA is not passed onto children. Heterosplasmy is when a single individual has more than 1 type of mitochondrial DNA in their body due to mutations. The most common disease with this type of inheritance is Mitochondrial Myopathy which presents with "Ragged Red" muscle fibers on biopsy
Polygenic or Multifactorial Inheritance is when the phenotype is not dictated by a single gene locus. These types of diseases are determined by an interaction between many contributing genetic and environmental factors.
Variable Expressivity = same genetic defect presents differently in different patients. Neurofibromatosis is an example
Mosaicism = when populations of cells within a single individual have different genotypes due to post-fertilization changes. Often in reference to chromosomal abnormalities caused by improper mitosis. Germline Mosacism is when only gametes (sperm and eggs) are affected by the genetic defect. Therefore, the individual would not show signs of the disease, but they could pass it on to their offspring
Pleiotrophy = a single genetic defect has multiple effects (same gene is expressed in many different tissues)
Incomplete Penetrance = not everyone with genetic defect gets the disease. Low penetrance means many people with the genotype do not show the phenotype
Pictures Used (In order of appearance)
• "Autosomal Dominant" by Domaina available at ttp://en.wikipedia.org/wiki/File:Autosomal_dominant_-_en.svg via Creative Commons 3.0 Attribution Share Alike
• "XlinkedRecessive" by US National Library of Medicine available at en.wikipedia.org/wiki/File:Xli... via Public Domain
• "Mitochondrial" By US National Library of Medicine available at en.wikipedia.org/wiki/File:Mit... by Public Domain

[@kranthikumarmukkera3499]

i have mitochondrial disease thanks for the video

[@JohnDoe-qs1nr]

thank you so much for these videos, they are a Godsend. I wish you taught at my med school.

[@jeffd4904]

Thanks for the information. This has helped reinforce what we are learning in PA school. I appreciate it.

[@stomponstep1989]

Jeff D Thanks for commenting!

[@nathanielcuevas47]

you are 100, bless ur soul

[@kristinedzigure2828]

Thank You. Very helpful

[@tobyme1]

thank you so much

[@samosman1769]

This was really helpful and easy to understand. Thanks :)

[@stomponstep1989]

+Sam Osman Thanks for commenting :)

[@AutumnPrinceProductions]

You explain this a lot better than my genomics teacher. thanks bro

[@stomponstep1989]

Atarien6 thanks for the comment and encourgement!

[@alejandravalle6542]

hello! great videos! extremely helpful and easy to understand. I take step 1 in the next couple of months. i am reviewing first aid and watching your videos as i follow along. im also doing u world questions. would you say this is suffice? also- do you have a video where you share your step 1 experience and how well you did? thank you so much!! :)

[@sonnetsehar5331]

Thanks, this video was helpful , but one suggestion do it a bit more comprehensive . Please can you do a detail videos along with clinical scenarios on genetic mapping and diagnosis

[@stomponstep1989]

Thanks so much for watching my video and giving me feedback. I really appreciate it. I agree with you that my videos certainly could be more comprehensive, but that is not the aim of this video series. My goal is to teach the highest yield points in as little time as possible to improve the viewers studying efficiency. As you cover a topic in more and more depth the content becomes lower and lower yield for the USMLE step 1 exam. If you are looking for a resource that covers topics comprehensively there are a lot of other books/videos that try to do that. It is also a time constraint issue. I am a current MS3 so I barely have enough time to make videos that just cover the essentials. But if there is enough demand out there after I finish covering all of the high yield material for Step 1 I may double back and start covering each section in more detail. Good luck with your studying!

[@StevePhillips]

Wow thank you!

[@stomponstep1989]

+Steve Phillips thanks for commenting!

[@harmeetkathuria731]

Good video. Please if you can use more animations.

[@anaphylastiks]

man its well known mutations are occasionally passed through the mito from father to son. i think you need to update these vids.

[@stomponstep1989]

***** Thanks for the comment and constructive criticism. I really appreciate it. The things you mentioned would be important to know for a genetics class, but this video series isn't a comprehensive genetics review. This video series just covers the highest yield material for the USMLE step 1 medical board exam. That test has relatively little genetics, only presents things in its most classic form and many of the questions were written many years ago (AKA the test is not fully up to date). So a very basic overview of inheritance is all that is needed for our purposes

[@anaphylastiks]

Hey I understand now. If you enjoy genetics, there are ground breaking studies happening right now, I became interested because I suffer from immune deficiencies . Recessive genes can be passed through mito paternally too, on occasion. meaning my father could have passed a recessive mutation to me. there are four of us excluding my parents,I am the eldest , the immune deficiencies filtered out through the siblings, yet I am the only one with anaphylactic reactions to all the pathogens. Trying to figure this out lead me into very complex stuff I do not understand, though I guess few do.

[@stomponstep1989]

***** I'm sorry to hear that. Good luck with your further research on the topic and I hope your family has good health moving forward

[@anaphylastiks]

also recessive genes , can skip generations and a dominant gene can become recessive ,,in a short a time as 3 births from same male dominant.

[@stomponstep1989]

If you liked this video and want me to make more please let me know by commenting, liking this video or by subscribing to my KZbin channel. If you have a question, please don’t hesitate to ask and I’ll try to answer it ASAP.