Ocular signs are present in 90% of heterozygous females.

The same attraction is not held by males for heterozygous females.

However, a greater severity of symptoms tends to affect males more often than heterozygous females.

In heterozygous females, the disease develops slowly.

The remaining tests were therefore carried out on heterozygous mutant females and hemizygous males.

It is difficult to distinguish the heterozygous males from the wild type but the black head and hackle of the heterozygous females is quite obvious.

For this reason, heterozygous females were excluded from the analysis.

By breeding these "knock-in" transgenic mice, they generated heterozygous females with both an M cone and an L cone.

The condition affects hemizygous males (i.e. all males), as well as homozygous, and in many cases heterozygous females.

In heterozygous females, whereby only one of the two X chromosomes carry the mutation, the disease develops slowly.