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What are the different ways a genetic condition can be inherited?
Reviewed by Medicinsk Expert•Last updated: 2026-10-22•Inheritance

What are the different ways a genetic condition can be inherited?

Genetic conditions caused by variants in a single gene typically follow specific inheritance patterns, though some disorders result from complex interactions or chromosomal changes.

Patterns of Inheritance

  • Autosomal dominant: One altered copy of the gene in each cell is sufficient to cause the disorder. Examples include Huntington's disease and Marfan syndrome.
  • Autosomal recessive: Variants occur in both copies of the gene in each cell. Parents are typically carriers without symptoms. Examples include cystic fibrosis and sickle cell disease.
  • X-linked dominant: Caused by variants on the X chromosome. In males, one copy causes the disorder; in females, one copy is sufficient but symptoms may be less severe. An example is fragile X syndrome.
  • X-linked recessive: Males are affected more frequently because they have only one X chromosome. Females would need variants in both copies to be affected. An example is hemophilia.
  • X-linked: Some conditions do not fit strictly into dominant or recessive categories. Examples include glucose-6-phosphate-dehydrogenase-deficiency and X-linked thrombocytopenia.
  • Y-linked: The variant is on the Y chromosome and can only be passed from father to son. Examples include Y chromosome infertility and some cases of Swyer syndrome.
  • Codominant: Two different versions of a gene are expressed, and both influence the trait. Examples include the ABO blood group and alpha-1 antitrypsin deficiency.
  • Mitochondrial: Also known as maternal inheritance, these variants occur in mitochondrial DNA. Only females can pass these to their children. An example is Leber hereditary optic neuropathy (LHON).

Complex and Chromosomal Disorders

Many conditions, such as heart disease, type 2 diabetes, schizophrenia, and certain cancers, are polygenic (caused by multiple genes) or result from gene-environment interactions. These do not follow the simple patterns listed above. Similarly, disorders caused by changes in the number or structure of chromosomes follow their own unique patterns.

Frequently Asked Questions

In X‑linked dominant inheritance, a single mutated X chromosome can cause the disease. A male who has the mutation will pass it to all of his daughters (who will be affected) but to none of his sons. A female carrier has a 50 % chance of passing the mutation to each child, regardless of sex.
Because males have only one X chromosome, a single mutated copy will cause the disease, so they are more frequently affected. A carrier mother has a 50 % chance of having an affected son and a 50 % chance of having a daughter who is a carrier (but usually not affected).
Conditions such as type 2 diabetes, schizophrenia, and many cancers are polygenic, meaning they result from variations in multiple genes and environmental factors, so they do not follow a single Mendelian inheritance pattern.
In autosomal dominant inheritance, only one copy of the mutated gene is needed to cause the disease, so an affected parent has a 50 % chance of passing the mutation to each child. In autosomal recessive inheritance, both parents must carry one copy of the mutation; each pregnancy has a 25 % chance of producing an affected child, a 50 % chance of a carrier child, and a 25 % chance of a child with two normal copies.
Y‑linked inheritance involves genes on the Y chromosome, which is only present in males. A man with a Y‑linked mutation will pass it to all of his sons, but a woman cannot inherit or transmit a Y‑linked mutation.
Mitochondrial inheritance comes from the mitochondria in the egg cell, so only the mother can pass mitochondrial mutations to her children. All of her children inherit the same mitochondrial DNA, regardless of sex, while the father’s mitochondria are not transmitted.
Mitochondrial DNA is inherited only from the mother. All of her children—both sons and daughters—will receive the mitochondrial mutation, but the father cannot pass it on to his children.
Codominance means that two different alleles at the same gene locus are both expressed in the phenotype. Each allele contributes to the trait, so offspring inherit a mix of both. An example is the ABO blood group, where a child inherits one allele from each parent and expresses both.
Source: MedlinePlus, National Library of Medicine

MedlinePlus brings together authoritative health information from the National Library of Medicine (NLM), the National Institutes of Health (NIH), and other government agencies and health-related organizations.

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