Autosomal dominant refers to one of the ways that a gene can be passed to offspring through families.
To be autosomal dominant, the gene only needs to come from one parent in order for the gene to be inherited.
Autosomal means that the chromosome affected is not a sex chromosome. Dominant means that even if the other parent has normal genes, the abnormal gene will prevail.
Each child from the parents will have a 50% chance of inheriting the gene, regardless of whether or not any other family members are affected.