X-linked inheritance and X-inactivation
X-linked recessive and dominant pedigrees, carrier risk calculations, and how skewed X-inactivation explains symptomatic female carriers of DMD, haemophilia and Fabry disease.
Tier 2Medical sciences concept
Written with AI assistance and fact-checked against the sources below. For exam study, not clinical decisions. How notes are made
At a glance
- Males are hemizygous for X genes, so a single pathogenic variant causes disease. Females have two X chromosomes, one of which is silenced in each cell.
- No male-to-male transmission is the pedigree signature of any X-linked trait.
- Female carriers of "recessive" X-linked disease are often mildly affected. Skewed X-inactivation decides how much.
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Sources
- Thompson & Thompson Genetics and Genomics in Medicine (9th ed.)Elsevier (Cohn, Scherer and Hamosh, eds), 2023
- GeneReviews: DystrophinopathiesUniversity of Washington, Seattle (NCBI Bookshelf NBK1119)
- GeneReviews: Hemophilia AUniversity of Washington, Seattle (NCBI Bookshelf NBK1404)
- GeneReviews: Fabry DiseaseUniversity of Washington, Seattle (NCBI Bookshelf NBK1292)
- van Galen KPM et al. A new hemophilia carrier nomenclature to define hemophilia in women and girls: communication from the SSC of the ISTH. J Thromb Haemost 2021;19:1883-7Journal of Thrombosis and Haemostasis, 2021
- Tiede A et al. International recommendations on the diagnosis and treatment of acquired hemophilia A. Haematologica 2020;105:1791-801Haematologica, 2020
- Last updated
- 14 November 2026
What changed
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