The Genetics of FVL, by Jennifer Rosenberg

+= one copy of the mutated gene -= one copy of the normal gene

--=normal +-=heterozygous for the mutated gene ++=homozygous for the mutated gene

 

If both parents are normal, each parent contributes one normal gene and all children (gray boxes) are normal (don't have the genetic condition):

Parents	-	-
-	--	--
-	--	--

 

If one parent is heterozygous(+-), and the other is normal(--), then the heterozygous parent passes on either a mutated gene or a normal gene, and the normal parent passes on a normal gene. There is a 50% chance of any offspring being heterozygous, and a 50% chance of them being normal.

P	+	-
-	+-	--
-	+-	--

 

If both parents are heterozygous(+-), each parent will pass along either a normal or a mutated gene. 25% chance of offspring being homozygous (++), 50% chance of offspring being heterozygous (+-) and 25% chance of any offspring being normal.

P	+	-
+	++	-+
-	+-	--

 

If one parent is homozygous(++) and the other is normal(--), all offspring will be heterozygous (+-).

P	+	+
-	+-	+-
-	+-	+-

 

If one parent is homozygous(++) and the other is heterozygous(+-), 50% chance of offspring being homozygous(++) and 50% chance of offspring being heterozygous(+-).

P	+	+
+	++	++
-	+-	+-

 

If both parents are homozygous (++) all children will be homozygous (++)

P	+	+
+	++	++
+	++	++

Contributions in design from Jennifer Rosenberg.