Polydactylism

Simba is one of our new cats. 

He has extra toes on his two front paws which is known as polydactyly.

I thought it was interesting that polydactylism is actually a dominant trait.  Basically, if either parent  has the gene on both arms of the autosome (non-sex chromosome) for it, a child will express the trait.  I remember learning about this in my biology classes in high school using Punnett squares and it was one of my favorite parts of the course, although I can't put my finger on why.  For those of you interested in the scientific definition, see below.

"Polydactylism (also known as hyperdactyly)

a congenital anomaly characterized by the presence of more than the normal number of fingers or toes. The condition is usually inherited as an autosomal-dominant characteristic...."

 

 

"autosomal-dominant inheritance:

a pattern of inheritance in which the transmission of a dominant allele on an autosome causes a trait to be expressed. Males and females are usually affected with equal frequency. If both parents are heterozygous (Aa), each of their children has a 50% chance of being heterozygous, a 25% chance of being homozygous for the dominant allele (AA), and a 25% chance of being homozygous for the recessive allele (aa); children with either of the first two genotypes will express the trait of the dominant allele. If one parent is homozygous for the dominant allele, all of the children will express the trait. Achondroplasia, osteogenesis imperfecta, polydactyly, Marfan's syndrome, and some neuromuscular disorders are transmitted through autosomal-dominant inheritance...."

polydactyly. (2012). In Mosby's Dictionary of Medicine, Nursing, & Health Professions.

hyperdactyly. (2012). In Mosby's Dictionary of Medicine, Nursing, & Health Professions.

autosomal-dominant inheritance. (2012). In Mosby's Dictionary of Medicine, Nursing, & Health Professions.