Now, before we examine four specific examples of human autosomal recessive diseases, let's actually recall and define what we mean by an autosomal recessive disease in the first place. Well, recall that in every single somatic cell of the human body, we have 23 pairs of homologous chromosomes. One of these pairs is known as the sex chromosomes. So in males we have the X and the Y. In females, we have the X and the X sex chromosome. And the other 22 pairs of homologous chromosomes are known as autosomes.