Patternsautosomal

Patternsautosomal refers to the inheritance patterns of genes located on autosomes, the non-sex chromosomes. In humans, these patterns apply to most inherited traits and diseases. Unlike X-linked patterns, autosomal traits typically show similar inheritance in males and females. The main Mendelian patterns are autosomal dominant and autosomal recessive.

Autosomal dominant disorders require only one mutant allele (one dose) for the phenotype to appear. Affected individuals usually have an affected parent, and both sexes transmit the trait with roughly equal frequency. Each child of an affected parent has about a 50% chance of inheriting the condition, assuming complete penetrance.

Autosomal recessive disorders require two mutant alleles for disease expression. Carriers, who have one normal and one mutant allele, are typically asymptomatic. Parents of an affected individual are often both carriers. Each child has a 25% risk of being affected, a 50% chance of being a carrier, and a 25% chance of being unaffected non-carrier. Consanguinity increases the likelihood that both parents carry the same mutation.

Penetrance and expressivity can modify these patterns. Incomplete penetrance means not all individuals with the disease allele show the phenotype; variable expressivity means the severity varies among individuals. De novo autosomal dominant mutations may appear in a family with no prior history.

Genetic counseling uses these patterns to estimate recurrence risks and informs testing strategies, including carrier screening. Some autosomal genes are affected by imprinting or polygenic influence, which can complicate simple Mendelian expectations.