Changes

!Pattern of inheritance !! Description !! Example

!Pattern of inheritance !! Description !! Example

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|X-linked dominant || •By mutations in genes on the  X chromosome,

|X-linked dominant || *By mutations in genes on the  X chromosome,

• In females, a mutation in one of the two copies of the gene in each cell is sufficient to cause the disorder.

* In females, a mutation in one of the two copies of the gene in each cell is sufficient to cause the disorder.

• In males, a mutation in the only copy of the gene in each cell causes the disorder.

* In males, a mutation in the only copy of the gene in each cell causes the disorder.

• In most cases, males experience more severe symptoms of the disorder than females. || fragile X syndrome

* In most cases, males experience more severe symptoms of the disorder than females. || fragile X syndrome

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|X-linked recessive || • Caused by mutations in genes on the X chromosome.

|X-linked recessive ||* Caused by mutations in genes on the X chromosome.

• A mutation would have to occur in both copies of the gene to cause the disorder in females.

* A mutation would have to occur in both copies of the gene to cause the disorder in females.

• In males, one altered copy of the gene in each cell is sufficient to cause the condition.

* In males, one altered copy of the gene in each cell is sufficient to cause the condition.

• Males are affected by X-linked recessive disorders much more frequently than females. ||hemophilia, Fabry disease

* Males are affected by X-linked recessive disorders much more frequently than females.  

 

|| hemophilia, Fabry disease

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| Y-linked || • Caused by mutations in genes on the Y chromosome.

| Y-linked || * Caused by mutations in genes on the Y chromosome.

• So, the mutation can only be passed from father to son. || Y chromosome infertility, some cases of Swyer syndrome

* So, the mutation can only be passed from father to son.

|| Y chromosome infertility, some cases of Swyer syndrome

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|Autosomal dominant || • One mutated copy of the gene in each cell is sufficient for a person to be affected.

|Autosomal dominant || * One mutated copy of the gene in each cell is sufficient for a person to be affected.

• An affected person can inherit the condition from an affected parent.  

* An affected person can inherit the condition from an affected parent.  

• the condition may result from a new mutation in the gene (e, without any family history)  

* the condition may result from a new mutation in the gene (e, without any family history)  

|| Huntington disease, Marfan syndrome

|| Huntington disease, Marfan syndrome

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|Autosomal recessive || • Both copies of the gene in each cell should have mutations.

|Autosomal recessive || * Both copies of the gene in each cell should have mutations.

• Typically not seen in every generation of an affected family.

* Typically not seen in every generation of an affected family.

|| cystic fibrosis, sickle cell disease

|| cystic fibrosis, sickle cell disease

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|Codominant || • Two different versions (alleles) of a gene are expressed.

|Codominant || * Two different versions (alleles) of a gene are expressed.

• Both alleles influence the genetic trait or determine the characteristics of the genetic condition.|| ABO blood group, alpha-1 antitrypsin deficiency

* Both alleles influence the genetic trait or determine the characteristics of the genetic condition.

|| ABO blood group, alpha-1 antitrypsin deficiency

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| Mitochondrial || • Also known as maternal inheritance

| Mitochondrial || * Also known as maternal inheritance

• Applies to the genes in mitochondrial DNA

* Applies to the genes in mitochondrial DNA

• Only females can pass on mitochondrial mutations to their children as only egg cells contribute mitochondria to the developing embryo. Leber hereditary optic neuropathy (LHON)

* Only females can pass on mitochondrial mutations to their children as only egg cells contribute mitochondria to the developing embryo.

||Leber hereditary optic neuropathy (LHON)

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