Inheritance Patterns

A qualified genetic counselor can assess your own personal and familial risk for FPF.  Please refer to the genetic counseling program page for more details on meeting with a genetic counselor at National Jewish Health. 

This section is not meant to address all personal, cultural, or ethical issues that individuals may face or to substitute for consultation with a genetics professional.

 

Half of our genetic information is passed onto our children.
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The Inheritance of Genes
Each individual has two copies of each gene in our bodies.  One set is inherited from the mother and the other set from the father.  Therefore, when an individual has children, there is a 50% chance of passing on one gene over the other. 

 

Autosomal Dominant Inheritance
FPF appears to transmit through families in an autosomal dominant fashion with reduced penetrance.  This is the most common inheritance pattern seen in families with FPF. 

“Autosomal” means that males and females can be affected equally, and both have a 50% chance of passing the genetic factor to each of their offspring.  The 50% chance of passing on the genetic factor is considered “dominant”. 

 

Example of autosomal dominant inheritance showing reduced penetrance.
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Reduced Penetrance

“Penetrance” refers to whether an individual who carries a mutation (or a genetic change) for a genetic disorder will develop disease or not.  In reduced (or incomplete) penetrance, an individual may or may not show disease, even though they carry a genetic mutation for the disorder.  It may take an environmental trigger (such as cigarette smoking) to cause the disease to show up. 

Reduced penetrance makes it difficult to determine risks for the development of disease in individuals who carry the genetic changes (mutations) for a genetic disorder.  In other words, if an individual is a carrier for a genetic mutation that can cause FPF, reduced penetrance means that person is not 100% guaranteed to develop FPF.
In some families, reduced penetrance can make the genetic disorder appear to “skip” generations.  Future studies on the genes thus far associated with FPF and the discovery of new genes may clarify penetrance.

 

Example of an autosomal recessive inheritance pattern.
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Other Modes of Inheritance
Autosomal recessive inheritance may need to be considered in cases with only one affected individual in a family or in families where only siblings are affected.