Genetic Condition Inheritance Patterns

Genetic conditions can be inherited in various patterns depending on the gene involved. These patterns describe how different gene variants (mutations) result in genetic disorders.

Patterns of Inheritance

Autosomal Dominant

• Description: One altered copy of the gene in each cell is enough to cause the disorder. It may be inherited from an affected parent or result from a new mutation.
• Examples:
  • Huntington's disease
  • Marfan syndrome

Autosomal Recessive

• Description: Variants must occur in both copies of the gene in each cell. Parents typically carry one altered copy but show no symptoms.
• Examples:
  • Cystic fibrosis
  • Sickle cell disease

X-linked Dominant

• Description: Disorders caused by variants in genes on the X chromosome. Males are affected more severely due to having one X chromosome.
• Examples:
  • Fragile X syndrome

X-linked Recessive

• Description: Also caused by X chromosome gene variants. Males are more frequently affected since they have only one X chromosome.
• Examples:
  • Hemophilia

X-linked

• Description: Sometimes treated as neither dominant nor recessive, involving alterations in X chromosome genes.
• Examples:
  • Glucose-6-phosphate dehydrogenase deficiency
  • X-linked thrombocytopenia

Y-linked

• Description: Disorders caused by variants on the Y chromosome, passed from father to son.
• Examples:
  • Y chromosome infertility
  • Some cases of Swyer syndrome

Codominant

• Description: Two different alleles are expressed, each influencing the genetic trait.
• Examples:
  • ABO blood group
  • Alpha-1 antitrypsin deficiency

Mitochondrial

• Description: Also known as maternal inheritance, involving genes in mitochondrial DNA passed from mothers to children.
• Examples:
  • Leber hereditary optic neuropathy (LHON)

Additional Notes

• Polygenic Conditions: Caused by multiple genes or gene-environment interactions, not following typical inheritance patterns.
  • Examples include heart disease, type 2 diabetes, schizophrenia, and some cancers.
• Chromosomal Conditions: Result from changes in the number or structure of chromosomes. More details can be found in resources discussing chromosomal inheritance.
• Other Genetic Factors: Include genomic imprinting and uniparental disomy, which can influence inheritance patterns.