Pattern

The pattern gene (Pg) in chickens is used for creating specific feather patterns like lacing and penciling (2). This gene organizes the black pigment in a concentric pattern around the feather, contributing to the distinctive lacing effect seen in some breeds (1)(3). Research has shown that the Pg gene works in conjunction with other genes, such as the melanotic gene (Ml) and the columbian gene (Co), to produce these patterns (1). The pattern gene by itself isn't noticeable without these other genes (2).

For example, the melanotic gene enhances and moves black pigment to the feather's edge, while the columbian gene restricts eumelanin in the center of the feather, leading to single lacing. When both the pattern and melanosis genes are present, you get double lacing patterns. The pattern gene is also responsible for enhancing autosomal barring, partridge, penciling, and other varieties. (2)

The gene is most often seen in homozygous form (two copies of the gene) for lacing, penciling, and other varieties. In heterozygous form (one copy of the gene), the lacing and overall pattern will be much less refined and complete, and smut is more common.

The APA recognizes golden and silver laced in cochins, wyandottes, and sebrights. In bantam Cornish, white laced red and blue laced red are also accepted. Polish is the only breed with the chamois accepted, or buff laced with white. Wyandottes, Hamburgs, and Rocks are recognized in the silver penciled variety. The gold penciling is only recognized in Hamburgs. Brahmas and Campines are breeds that also utilize the pattern gene for different varieties. (3)

Breeding with Patterning:

This gene is hard to draw a complete punnett square for because it doesn't work by itself to create the different patterns but rather works in combination with other genes.