What are some possible genotypes for parents?

Geneticists use 2 by 2 tables, called Punnett Squares, to predict the possible genetic traits (or genotypes) for children. Below are two Punnett Squares depicting possible CLS inheritance.

Table 1: Affected father (X`Y), unaffected mother (XX).

	X`	Y
X	X`X	XY
X	X`X	XY

Male children in this scenario will not be affected. Female children will be affected by the dominant trait on the X chromosome.

Table 2: Affected mother, heterozygous (X`X), unaffected father (XY).

	X	Y
X`	X`X	X`Y
X	XX	XY

In this scenario, 50 percent of daughters and 50 percent of sons will be affected.

In short: If the mother is heterozygous (X`X) she will pass it on to about half (50 percent) of her children.
If the mother is homozygous (X`X`) she will pass it on to ALL of her children.
If the father is affected (X`Y) he will pass the trait on to his daughters, but not to his sons.

Depending on the severity of the disorder, however, many CLS patients do not have children. Instead, CLS is often the result of a new mutation on the X chromosome.