Autosomal Recessive Inheritance
When a disease or condition runs in families, it is called an inherited disease. You
inherit a disease through your genes. Genes are the tiny blueprints your body uses
for making proteins. Proteins are substances your body needs to develop and work the
way it should.
Most genes come in pairs. You inherit one half of the pair from your mother and the
other half from your father. A mutation is a change in a gene that causes it to be
different from the copy you got from your parents. A mutation can cause a disease
or condition. Or it can cause no problems at all.
Each gene tells your body to work in a specific way. Often genes work together. Sometimes
a single gene pair tells your body what to do. Sometimes you need both genes in a
pair to be exactly the same to have something happen. This is called autosomal recessive
Autosomal recessive genes
Your genes are grouped together on structures called chromosomes. You have 23 pairs
of chromosomes. One of these 23 pairs of chromosomes is called the sex chromosomes.
This pair determines if you are female or male.
Autosomal inheritance of a gene means that the gene is located on one of the 22 other
pairs of chromosomes. This means that boys and girls (or men and women) are equally
likely to have the gene. Recessive means that you must inherit both copies of the
gene in order for you to have the trait. If you have only one copy of the recessive
gene, you won’t have the trait or the disease. Instead, you will be a "carrier" for
the trait or disease. But you won’t be able to tell that you are a carrier without
a genetic test.
Most people don’t know they have a recessive gene for a disease until they have a
child with the disease. Or they may find out if they have a brother or a sister with
an inherited disease and learn they have a recessive gene. Once parents have had a
child with a recessive disease, they have a 1 in 4 chance of having another child
with the same disease. This is true for every child born after that first child. Their
other children have a 2 in 4 chance of being a carrier of the recessive gene.
The birth of a child with a recessive condition is often a total surprise to a family.
This is because in most cases the parents had no family history of the condition.
Your healthcare provider may ask you about more distant relatives who might have had
similar conditions in the past.
Experts estimate that all people carry at least 1 recessive gene that could cause
genetic diseases or conditions. But the only way you’ll know that you have the gene
is if you have a child with a partner who has the same copy of the gene. Even then,
your child may not have the disease—because of the 1-in-4 chance.
Mutations in certain genes have happened over time in different parts of the world.
Certain ethnic groups are more likely to carry certain recessive gene mutations, because
of where the mutation started. For instance, people of African descent are more likely
to have sickle cell disease. Cystic fibrosis is more common in Caucasians.