Autosomal recessive disorder

Autosomal recessive disorder refers to a genetic disorder that occurs when an individual inherits two copies of a recessive gene for the same trait, one from each parent. These disorders are typically not manifested unless an individual receives a recessive allele from both parents. If an individual receives one normal allele and one mutated allele, they are considered a carrier of the disorder but usually do not show symptoms.

Genetics of Autosomal Recessive Disorders

Autosomal recessive disorders are caused by mutations in genes located on the autosomes, which are the numbered chromosomes that do not determine sex (i.e., not the X or Y chromosomes). Each person has two copies of each autosome and therefore two copies of each gene located on these chromosomes—one inherited from each parent.

In autosomal recessive inheritance, both parents must either be carriers or affected. Carriers have one normal allele and one mutated allele but do not show symptoms of the disorder. When two carriers of the same autosomal recessive disorder have a child, there is a:

• 25% chance the child will inherit two mutated alleles (affected)
• 50% chance the child will inherit one normal and one mutated allele (carrier)
• 25% chance the child will inherit two normal alleles (unaffected)

Common Autosomal Recessive Disorders

Some well-known autosomal recessive disorders include:

• Cystic fibrosis, which affects the respiratory, digestive, and reproductive systems
• Sickle cell disease, a condition that affects the red blood cells and can lead to anemia and pain
• Phenylketonuria (PKU), which affects how the body processes the amino acid phenylalanine
• Tay-Sachs disease, which leads to progressive deterioration of nerve cells and mental and physical abilities

Diagnosis and Management

Diagnosis of autosomal recessive disorders often involves genetic testing to identify mutations in specific genes. Prenatal testing is also available for some disorders, allowing parents to know if their child will be affected by or a carrier of a disorder.

Management and treatment vary depending on the specific disorder but may include dietary modifications, medications, physical therapy, and in some cases, surgical interventions. Supportive care and regular monitoring by healthcare professionals are crucial in managing health complications associated with these disorders.

Genetic Counseling

Genetic counseling is recommended for individuals who have a family history of an autosomal recessive disorder or are known carriers of one. Genetic counselors can provide information about the risk of passing the disorder to children and discuss the options available for prenatal testing and reproductive technologies.

See Also

• Genetic disorder
• Autosomal dominant disorder
• X-linked recessive inheritance