Autosomal recessive is one of several ways that a trait, disorder, or disease can be passed down through families. An autosomal recessive disorder means that two copies of an abnormal gene, one from each parent, must be present in a child for the disease or trait to develop. If an individual only has one copy of the gene, they are called carriers, but they do not present with the disorder. Autosomal recessive traits occur when two carrier parents have children and both pass on the same abnormal gene.