Home > Autosomal recessive

In opposition to autosomal dominant trait, a recessive trait only becomes phenotypically apparent when two copies of a gene (two alleles) are present, i.e. the propositus is homozygous for the trait.

Recessive genetic disorders occur when both parents are carriers and each contribute an allele to the embryo. As both parents are heterozygous for the disorder, the chance of two disease alleles landing in one of their offspring is 25% (in autosomal dominant traits this is higher). 50% of the children (or 2/3 of the remaining ones) are carriers. When one of the parents is homozygous, the trait will only show in his/her offspring if the other parent is also a carrier. In that case, the chance of disease in the offspring is 50%.

Other forms of inheritance are autosomal dominant, X-linked and mitochondrial.

Examples of recessive disorders:

• Sickle cell anemia
• Cystic fibrosis
• Tay-Sachs diseaseTay-Sachs disease is a fatal genetic disorder, inherited in an autosommal recessive pattern, in which harmful quantities of a fatty substance called ganglioside GM2 accumulate in the nerve cells in the brain. Signs and symptoms Infants with Tay-Sachs dise
• Chronic granulomatous diseaseIn medicine ( genetics and pediatrics) chronic granulomatous disease (CGD) is a hereditary disease where neutrophil granulocytes are unable to destroy ingested pathogens. It leads to the formation of granulomata in many organs. Pathophysiology Neutrophils

See also

• Recessive geneIn genetics, the term recessive gene refers to an allele that causes a phenotype (visible or detectable characteristic) that is only seen in a homozygous genotype (an organism that has two copies of the same allele). Every person has two copies of every g
• Genetics