Autosomal dominant is a pattern of Mendelian
inheritance whereby an affected individual possesses one copy of a mutant
allele and one normal allele. (In contrast,
recessive diseases require that the individual have two copies of the mutant
allele.) Individuals with autosomal dominant diseases have a 50-50 chance of passing the mutant allele and hence the
disorder onto their children. Examples of autosomal dominant diseases include Huntington's disease, neurofibromatosis, achondroplasia (in some cases), and
polycystic kidney disease.
Compare with autosomal recessive.
Source: National Human Genome