Autosomal Dominant Inheritance in Human Genetics

Autosomal Dominant and Autosomal Recessive are two patterns of inheritance that describe how certain genetic traits or disorders are passed down from parents to their offspring. These terms refer to the location of the responsible gene on autosomal chromosomes (non-sex chromosomes) and the way in which the presence of certain alleles (gene variants) leads to the expression of traits or disorders.

1. Autosomal Dominant Inheritance:
In an autosomal dominant inheritance pattern, a single copy of a mutated gene from one parent is sufficient to cause the trait or disorder to be expressed in the offspring. This means that if one parent carries the dominant allele for a particular trait or disorder, there is a 50% chance that their offspring will inherit the trait or disorder. The trait or disorder often appears in every generation of a family affected by it.

Key points of autosomal dominant inheritance:
- Each affected individual usually has an affected parent.
- An affected person has a 50% chance of passing on the trait to each of their children.
- Unaffected individuals do not pass the trait to their offspring.
- Examples of autosomal dominant disorders include Huntington's disease and Marfan syndrome.

2. Autosomal Recessive Inheritance:
In an autosomal recessive inheritance pattern, both copies of the gene (one from each parent) must carry a mutated allele in order for the trait or disorder to be expressed in the offspring. Individuals who inherit only one mutated allele are carriers of the trait but do not exhibit the disorder themselves. If two carriers have children together, there is a 25% chance of having an affected child, a 50% chance of having an unaffected carrier, and a 25% chance of having an unaffected, non-carrier child.

Key points of autosomal recessive inheritance:
- Affected individuals often have unaffected parents who are carriers of the trait.
- Carriers (heterozygous individuals) do not show the disorder but can pass the mutated allele to their offspring.
- When two carriers have children, there's a risk of having affected offspring.
- Examples of autosomal recessive disorders include cystic fibrosis and sickle cell anemia.

It's important to note that genetic inheritance can be more complex than these simplified explanations, as there are various factors that can influence the expression of traits and disorders, such as incomplete dominance, codominance, and the influence of multiple genes.

Genetic counseling and testing can provide more accurate information about inheritance patterns and the likelihood of passing on genetic traits or disorders.

[USMLEpass]

Correction: in X-Linked diseases, heterozygous means one copy is mutated and homozygous means two copies are defected

[jareldperez]

I think the inheritance of heterozygous mother in X-linked recessive is 50% of all boys will become affected. To be specific, 25% chance of having an unaffected son, a 25% chance of having an affected son, a 25% chance of having an unaffected daughter and a 25% chance of having a daughter who also is a carrier.

[unitedasiatv]

Awesome content!! Straight to the point!! Looking forwards to more productively helpful content videos!!! Thanks so much!

[umerkhan]

can you please clearify, what i understand by HETEROZYGOUS IS WHEN ONE COPY OD GENE IS AFFECTED and when two copies of genes are affected we call it HOMOZYGOUS but in x linked dominent you mentioned that heterozygous is when two copies of gene are affected. your explanation will be highly appreciated

[neetbiologybyshivsir]

Sorry sir, you have wrong explained about x linked. Dominant inheritance.

[chui]

this almost feels like it's t'challa teaching me

[kyrucial]

I like the effort but the explanation is kinda … 😊

[saddamhussain-xgvy]

Genetics is the most confusing subject