Genetics

Genetic Signals "switches"
When the skeleton is forming in the embryo, a genetic signal instructs the body where and in what size and shape to form bone. In FOP, a gene mutation alters these instructions and leads to malformation of the big toes, a finding often noted at birth. A genetic signal later tells the body after birth to form extra bone at an improper time and place. A mutation of a single gene is likely responsible for all of the skeletal malformations of FOP. The goal of research is to find that gene and stop it from doing harm.

Patterns of Inheritance
FOP is an autosomal dominant condition.This means that a person who carries the gene for FOP will have FOP. In most cases, FOP is a new mutation, or an accident of nature. A sibling or other family member who does not have FOP is no more likely to have a child who has FOP than a person in the general population: that is, one chance in two million. Parents who do not have FOP should be assured that the chance of having a second child with FOP is extremely remote. Though most cases arise from unaffected parents, a person with FOP has a 50% chance of passing it on to a child.

Finding the FOP Gene
Scientists estimate that there are 50,000 to 100,000 pieces of genetic information, or genes, in each of our cells. At this time, researchers do not know which gene causes FOP.They also do not know what causes the "genetic switch" which controls FOP to turn on and off at various stages in an individual's life. However, in 1998 researchers narrowed the location of the gene to the long arm of chromosome 4, an extremely important discovery that will make it easier to eventually pinpoint the FOP gene. However, there is still a lot of work to be done before the gene can be found. There is a dire need for more families, especially muiltigenerational ones.

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