Autosomal Recessive Inheritance Autosomal recessive inheritance
is the most common type of inheritance for retinal dystrophies.
When this type of condition is present in a family, it is often
seen only in one child or in siblings, not in the parents or
other relatives. As shown in the figure, to have symptoms of
BCD, an individual must have two copies of the same disease
gene. We all have two copies of each gene, since we inherit one
from our father and one from our mother. In the figure above,
the N stands for the normal copy of the BCD gene and the B
stands for the abnormal copy of the BCD gene. Both parents have
an N gene and a B gene and are therefore called "carriers." In
this scenario, there is a 75 percent chance that a child will
not have Bietti's crystalline dystrophy. In each child there is
a 50 percent chance to inherit the N gene and a 50 percent
chance to inherit the B gene from each parent. There is: - a 25
percent chance that a child will inherit both N genes and be
unaffected - a 50 percent ch