Editing Genetic disorder (section)

=== X-linked dominant ===
[[File:Human karyotype with bands and sub-bands.png|thumb|Schematic [[karyotype|karyogram]] showing an overview of the [[human genome]]. It shows annotated [[Locus (genetics)|bands and sub-bands]] as used in the [[International System for Human Cytogenomic Nomenclature|nomenclature of genetic disorders]]. It shows 22 [[homologous chromosome]]s, both the female (XX) and male (XY) versions of the [[sex chromosome]] (bottom right), as well as the [[human mitochondrial genetics|mitochondrial genome]] (to scale at bottom left).{{cn|date=March 2023}}{{further|Karyotype}}]]
{{Main|X-linked dominant}}
X-linked dominant disorders are caused by mutations in genes on the [[X chromosome]]. Only a few disorders have this inheritance pattern, with a prime example being [[X-linked hypophosphatemic rickets]]. Males and females are both affected in these disorders, with males typically being more severely affected than females. Some X-linked dominant conditions, such as [[Rett syndrome]], [[incontinentia pigmenti]] type 2, and [[Aicardi syndrome]], are usually fatal in males either ''in utero'' or shortly after birth, and are therefore predominantly seen in females. Exceptions to this finding are extremely rare cases in which boys with [[Klinefelter syndrome]] (44+xxy) also inherit an X-linked dominant condition and exhibit symptoms more similar to those of a female in terms of disease severity. The chance of passing on an X-linked dominant disorder differs between men and women. The sons of a man with an X-linked dominant disorder will all be unaffected (since they receive their father's Y chromosome), but his daughters will all inherit the condition. A woman with an X-linked dominant disorder has a 50% chance of having an affected foetus with each pregnancy, although in cases such as incontinentia pigmenti, only female offspring are generally viable.