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Genetic and Rare Diseases Information Center (GARD)

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Nance-Horan syndrome

Other Names for this Disease
  • Cataract dental syndrome
  • Cataract X-linked with Hutchinsonian teeth
  • Mesiodens cataract syndrome
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How is Nance-Horan syndrome inherited?

Nance-Horan syndrome is inherited as an X-linked dominant trait. In X-linked dominant inheritance, both males and females can be affected by a condition. However, affected males tend to have more severe features than females.[1]

X-linked conditions result from mutations of a gene located on an X chromosome. Females have two X chromosomes, but males have one X chromosome and one Y chromosome. In females, disease traits resulting from the abnormal copy of a gene on one X chromosome can be 'masked' by the normal copy of the gene on the other X chromosome. Because only one functioning X chromosome is required in males and females, one of the X chromosomes in each cell of a female is essentially 'turned off,' usually in a random pattern (X chromosome inactivation). Therefore, if the X chromosome with the gene mutation is activated in some cells, female carriers may have some mild features of the disorder. However, since males only have one X chromosome, they will likely fully express a condition if they inherit a gene mutation that is located on the X chromosome.[1]
Last updated: 8/22/2011

  1. Nance-Horan Syndrome. National Organization for Rare Disorders (NORD). 2011; Accessed 8/22/2011.