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Genetic and Rare Diseases Information Center (GARD)

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Ocular albinism type 1


Other Names for this Disease

  • Nettleship-Falls type ocular albinism
  • OA1
  • X-linked ocular albinism
  • X-linked recessive ocular albinism
  • XLOA
See Disclaimer regarding information on this site. Some links on this page may take you to organizations outside of the National Institutes of Health.

Your Question

I'm a woman who has ocular albinism 1. I'm the only person in my family that has it. My question is: I am pregnant and I want to know my chances of having children with ocular albinism? Will my sons or daughters be more affected?

Our Answer

We have identified the following information that we hope you find helpful. If you still have questions, please contact us.

What is ocular albinism type 1?

Ocular albinism type 1 (OA1) is a genetic eye condition that primarily affects males. Signs and symptoms may include reduced coloring of the iris and retina (ocular hypopigmentation); foveal hypoplasia; rapid, involuntary eye movements (nystagmus); poor vision; poor depth perception; eyes that do not look in the same direction (strabismus); and increased sensitivity to light.[1][2] It is caused by mutations in the GPR143 gene and is inherited in an X-linked recessive manner.[1][2] Females have been affected in rare instances. Treatment consists of visual correction with eyeglasses or contact lenses; use of sunglasses or special filter glasses for light sensitivity; and in some cases, extraocular muscle surgery to restore alignment and/or improve a head posture that is associated with nystagmus.[2]
Last updated: 6/27/2013

What causes ocular albinism type 1?

Ocular albinism type 1 is caused by mutations in the GPR143 gene.[2] This gene provides instructions for making a protein that plays a role in pigmentation (coloring) of the eyes and skin. It helps control the growth of melanosomes, which are structures inside the cells that make and store a pigment called melanin. Melanin also plays a role in vision in the retina. Mutations in the GPR143 gene can affect the protein's ability to do its job. As a result, melanosomes in skin and retinal cell can grow abnormally large, contributing to the signs and symptoms of the condition.[1]
Last updated: 6/27/2013

How is ocular albinism type 1 inherited? Are males or females more likely to be affected?

Ocular albinism type 1 is usually caused by mutation in the GPR143 gene. In these cases, the condition is passed through families in an “X-linked” pattern.  In X-linked conditions males are more commonly affected than females. This is because males have only one X chromosome and therefore one copy of the GPR143 gene. Females have two X chromosomes and therefore two copies of the GPR143 gene. If females have a mutation in one of their GPR143 genes, they still have a second normal GPR143 gene to compensate. These women usually do not experience vision loss or other significant eye abnormalities. They may have mild changes in retinal pigmentation that can be detected during an eye examination.

 

Occasionally females will have more significant signs and symptoms of ocular albinism type 1. This may be due to:

  • A phenomenon called skewed X-chromosome inactivation 
  • Having inherited two mutations of the GPR143 gene 
  • Having a partial deletion of the X chromosome

To learn more about X inactivation please visit the following link. http://ghr.nlm.nih.gov/glossary=xchromosomeinactivation

Last updated: 3/31/2014

I am a female with ocular albinism type 1 and I'm pregnant. Are my children at risk for inheriting this condition?

We understand your desire to learn more about ocular albinism type 1 and what it may mean for your current and future pregnancies. To know with certainty your chances of having a baby with this condition, we recommend that you speak with a genetics professional. Ocular albinism type 1 is usually inherited in an X-linked recessive fashion. Usually, the sons of a woman with ocular albinism will each have the condition and her daughters will all be carriers for the condition. However, this is not always the case depending on the reason why a woman is affected.  

We strongly recommend you discuss your concerns with a genetics professional A genetics professional will try to determine why you are affected and what the underlying cause of your condition is first. This information will be important in estimating your recurrence risk. Genetic professionals are a source of information for individuals and families regarding genetic diagnosis, natural history, treatment, mode of inheritance, and genetic risks to other family members. To find a genetics clinic, we recommend that you contact your primary doctor for a referral. Click here to learn more about genetic consultations.

The following online resources can also help you find a genetics professional in your community:

The National Society of Genetic Counselors provides a searchable directory of US and international genetic counseling services.

The American College of Medical Genetics has a searchable database of US genetics clinics.

The University of Kansas Medical Center provides a list of US and international genetic centers, clinics, and departments.

The American Society of Human Genetics maintains a database of its members, which includes individuals who live outside of the United States. Visit the link to obtain a list of the geneticists in your country, some of whom may be researchers that do not provide medical care.

Last updated: 3/31/2014

References
Other Names for this Disease
  • Nettleship-Falls type ocular albinism
  • OA1
  • X-linked ocular albinism
  • X-linked recessive ocular albinism
  • XLOA
See Disclaimer regarding information on this site. Some links on this page may take you to organizations outside of the National Institutes of Health.