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. And so what we mean by an autosomal recessive disease is that genetic abnormality exists on one of the genes or both of the genes on the autosomal homologous chromosome pair. So this is a type of abnormality that exists on autosomes and not on sex chromosomes. So let's actually define what we mean by recessive disease.