Genetic family trees allow you to map out the possibilities of passing on specific genes such as the sickle cell gene. In order to map out your genetic tree you start with two parents.

 

In this case both parents have sickle cell trait, meaning they each carry one sickle cell gene each. (AS x AS)

 

The following are the four possibilities a couple can encounter for each pregnancy.

Possibility #1

With two parents that are carriers, or have sickle cell trait, there is a one-in-four or 25% chance (per pregnancy) that a child will be born normal (characterized as ‘AA’), meaning they did not inherit any sickle cell genes.

 

This child inherited a normal gene (A) from their mom, and another normal gene (A) from their father.

 

Possibility #2

With two parents that are carriers, or have sickle cell trait, there is a two-in-four or 50% chance (per pregnancy) that a child will be born with sickle cell trait (characterized as ‘AS’), meaning they inherited one sickle cell gene and one normal gene.

 

This child inherited a normal gene (A) from their mom, and a sickle cell gene (S) from their father.

 

Possibility #3

With two parents that are carriers, or have sickle cell trait, there is a two-in-four or 50% chance (per pregnancy) that a child will be born with sickle cell trait (characterized as ‘AS’), meaning they inherited one sickle cell gene and one normal gene.

 

This child inherited a sickle cell gene (S) from their mom, and a normal gene (A) from their father.

 

Possibility #4

With two parents that are carriers, or have sickle cell trait, there is a one-in-four or 25% chance (per pregnancy) that a child will be born with sickle cell disease (characterized as ‘SS’), meaning they inherited a sickle cell gene from each parent.

 

This child inherited a sickle cell gene (S) from their mom, and another sickle cell gene (S) from their father.

 

Entire Sickle Cell Genetic Family Tree

AS X AS

 

Mom: Sickle Cell Trait (AS)

Dad: Sickle Cell Trait (AS)

 

All-in-all, there is a 25% chance of have a normal child, a 50% chance of having a child with sickle cell trait, and a 25% chance of having a child with sickle cell disease.

IMPORTANT: Please keep in mind these are the genetic trees for two parents who have sickle cell trait. There are many other combinations that can be mapped out depending on couple's genotypes.

 

Here are a few examples:

 

SS x AA

 

Mom: Sickle Cell Disease (SS)

Dad: Normal (AA)

 

Possibility #1: AS

Possibility #2: AS

Possibility #3: AS

Possibility #4: AS

 

There is a four-in-four or 100% chance all children will have sickle cell trait (AS).

 

AS x SC

 

Mom: Sickle Cell Trait (AS)

Dad: Sickle C Disease (SC)

 

Possibility #1: AS (Sickle Cell Trait)

Possibility #2: SS (Sickle Cell Anemia)

Possibility #3: SC (Sickle C Disease)

Possibility #4: AC (C Trait - not a sickle cell gene)

 

There is a one-in-four or 25% chance a child will have sickle cell trait; one-in-four or 25% chance a child will have sickle cell anemia (SS); one-in-four or 25% chance a child will have sickle c disease (SC); and one-in-four or 25% chance a child will have c-trait (AC).

 

AA x AS

 

Mom: Normal (AA)

Dad: Sickle Cell Trait (AS)

 

Possibility #1: AA (Normal)

Possibility #2: AS (Sickle Cell Trait)

Possibility #3: AA (Normal)

Possibility #4: AS (Sickle Cell Trait)

 

There is a two-in-four or 50% chance a child will have have no sickle cell genes (normal) (AA); two-in-four or 50% chance a child will have sickle cell trait (AS).

DISCLAIMER: Information on this site is intended for educational purposes only and should not be used as a substitute for professional diagnosis and treatment.

 

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