An autosome is chromosomes apart from the sex chromosomes in a eukaryotic cell. In humans, the X and Y chromosomes are the sex chromosomes. All the chromosomes other than the sex chromosomes are autosomes. There are 22 homologous pairs of autosomes in humans. Each autosome has several genes each of which performs certain unique functions. Different cell types in a eukaryote express a different combination of genes that enables cellular functions in eukaryotic organisms. Most eukaryotic organisms reproduce through sexual reproduction, meaning that each individual has two copies of each chromosome. One copy is inherited from one parent, while the other is inherited from the other parent.
All human autosomes have been identified and mapped by extracting the chromosomes from a cell arrested in metaphase or prometaphase and then staining them with a type of dye. These chromosomes are typically viewed as karyograms for easy comparison. Clinical geneticists can compare the karyogram of an individual to a reference karyogram to discover the cytogenetic basis of certain phenotypes. For example, the karyogram of someone with Patau Syndrome would show that they possess three copies of chromosome 13. Karyograms and staining techniques can only detect large-scale disruptions to chromosomes, chromosomal aberrations smaller than a few million base pairs generally cannot be seen on a karyogram.
Autosomal Genetic Disorders
Autosomal genetic disorders can arise due to several causes, some of the most common being nondisjunction in parental germ cells or Mendelian inheritance of deleterious alleles from parents. Autosomal genetic disorders that exhibit Mendelian inheritance can be inherited either in an autosomal dominant or recessive fashion. These disorders manifest in and are passed on by either sex with equal frequency. Autosomal dominant disorders are often present in both parent and child, as the child needs to inherit only one copy of the deleterious allele to manifest the disease.