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Reviewed July 2014
What is Gillespie syndrome?
Gillespie syndrome is a disorder that involves eye abnormalities, problems with balance and coordinating movements (ataxia), and mild to moderate intellectual disability.
Gillespie syndrome is characterized by aniridia, which is the absence of the colored part of the eye (the iris). In most affected individuals, only part of the iris is missing (partial aniridia) in both eyes, but in some affected individuals, partial aniridia affects only one eye, or the entire iris is missing (complete aniridia) in one or both eyes. The absence of all or part of the iris can cause blurry vision (reduced visual acuity) and increased sensitivity to light (photophobia). Rapid, involuntary eye movements (nystagmus) can also occur in Gillespie syndrome.
The balance and movement problems in Gillespie syndrome result from underdevelopment (hypoplasia) of a part of the brain called the cerebellum. This abnormality can cause delayed development of motor skills such as walking. In addition, difficulty controlling the muscles in the mouth can lead to delayed speech development. The difficulties with coordination generally become noticeable in early childhood when the individual is learning these skills. People with Gillespie syndrome usually continue to have an unsteady gait and speech problems. However, the problems do not get worse over time, and in some cases they improve slightly.
Other features of Gillespie syndrome can include abnormalities in the bones of the spine (vertebrae) and malformations of the heart.
Read more about aniridia.
How common is Gillespie syndrome?
The prevalence of Gillespie syndrome is unknown. Only a few dozen affected individuals have been described in the medical literature. It has been estimated that Gillespie syndrome accounts for about 2 percent of cases of aniridia.
What genes are related to Gillespie syndrome?
Gillespie syndrome can be caused by mutations in the PAX6 gene. The PAX6 gene provides instructions for making a protein that is involved in early development, including the development of the eyes and brain. The PAX6 protein attaches (binds) to specific regions of DNA and regulates the activity of other genes. On the basis of this role, the PAX6 protein is called a transcription factor.
Mutations in the PAX6 gene result in the absence of the PAX6 protein or production of a nonfunctional PAX6 protein that is unable to bind to DNA and regulate the activity of other genes. This lack of functional protein disrupts embryonic development, especially the development of the eyes and brain, leading to the signs and symptoms of Gillespie syndrome.
Most people with Gillespie syndrome do not have mutations in the PAX6 gene. In these affected individuals, the cause of the disorder is unknown.
Read more about the PAX6 gene.
How do people inherit Gillespie syndrome?
In some cases, including those in which Gillespie syndrome is caused by PAX6 gene mutations, the condition occurs in an autosomal dominant pattern, which means one copy of the altered gene in each cell is sufficient to cause the disorder. Some affected individuals inherit the mutation from one affected parent. Other cases result from new mutations in the gene and occur in people with no history of the disorder in their family.
Gillespie syndrome can also be inherited in an autosomal recessive pattern, which means both copies of a gene in each cell have mutations. The gene or genes involved in these cases are unknown. The parents of an individual with an autosomal recessive condition each carry one copy of the mutated gene, but they typically do not show signs and symptoms of the condition.
Where can I find information about diagnosis or management of Gillespie syndrome?
These resources address the diagnosis or management of Gillespie syndrome and may include treatment providers.
General information about the diagnosis and management of genetic conditions is available in the Handbook. Read more about genetic testing, particularly the difference between clinical tests and research tests.
To locate a healthcare provider, see How can I find a genetics professional in my area? in the Handbook.
Where can I find additional information about Gillespie syndrome?
You may find the following resources about Gillespie syndrome helpful. These materials are written for the general public.
You may also be interested in these resources, which are designed for healthcare professionals and researchers.
What other names do people use for Gillespie syndrome?
What if I still have specific questions about Gillespie syndrome?
Where can I find general information about genetic conditions?
The Handbook provides basic information about genetics in clear language.
These links provide additional genetics resources that may be useful.
What glossary definitions help with understanding Gillespie syndrome?
ataxia ; autosomal ; autosomal dominant ; autosomal recessive ; cell ; cerebellum ; deficiency ; disability ; DNA ; embryonic ; gait ; gene ; hypoplasia ; inherit ; inherited ; involuntary ; mental retardation ; motor ; mutation ; nystagmus ; photophobia ; prevalence ; protein ; recessive ; sensitivity ; syndrome ; transcription ; transcription factor ; visual acuity
You may find definitions for these and many other terms in the Genetics Home Reference Glossary.
See also Understanding Medical Terminology.
References (5 links)
The resources on this site should not be used as a substitute for professional medical care or advice. Users seeking information about a personal genetic disease, syndrome, or condition should consult with a qualified healthcare professional. See How can I find a genetics professional in my area? in the Handbook.