What is Strabismus?Strabismus is a disorder in which the two eyes are not correctly aligned. If untreated it can lead to amblyopia – also called 'lazy eye' – a condition in which the vision in one eye deteriorates. Strabismus and amblyopia are together the most common causes of visual impairment in children.
Current treatment alternatives
Current treatments for strabismus and amblyopia include: surgically realigning the eyes, patching one eye or performing eye exercises to strengthen the coordination of the two eyes. Although many children with strabismus or amblyopia can be effectively treated, a better understanding of the causes of these disorders would permit a more accurate assessment of which treatment plan is most likely to succeed for each child.
University of Utah & Johns Hopkins Genetics of Strabismus Study
Doctors Kang Zhang (University of Utah School of Medicine) and Jeremy Nathans (Johns Hopkins University School of Medicine) are conducting a study to identify the role of inheritance in strabismus. It has long been known that strabismus tends to run in families, but the precise role that genes play in making some people more likely to develop strabismus is still unknown. If the mechanism of this genetic predisposition can be clarified, it is very likely to lead to improved treatment for future generations of strabismus patients.
The goal of this study is to identify the genes that predispose some individuals to have a misalignment of the eyes, referred to as strabismus. A related disorder called amblyopia (“lazy-eye”) results in the loss of vision in one eye due to the preferential use of the other eye. Some people who have strabismus will eventually suffer from amblyopia, whereas others will not. Both of these disorders tend to run in families, and are likely to arise from the same basic problem with coordinating vision in the two eyes. If the genes responsible for a predisposition to strabismus or amblyopia can be identified, the knowledge gained will help identify children who are at higher risk for these problems and it will also help to improve decisions regarding which therapeutic approach is most likely to help each child.
The study involves collecting information on eye alignment and function from family members to determine the pattern of inheritance of strabismus and amblyopia, and then analyzing the genetic material (DNA) obtained from a standard-size blood sample. The identities of all participants and any information pertaining to the participants will be stored in coded form to maintain confidentiality.
An invitation to participate in the Genetics of Strabismus Study
Success in identifying the genes responsible for a predisposition to strabismus or amblyopia depends on studying families in which multiple members have one or both of these disorders. If there are five or more individuals in your immediate or extended family who have strabismus or amblyopia - or who had either problem when they were younger – we invite you to contact us to learn more about participating in our ongoing Genetics of Strabismus study. Both affected and unaffected family members will be able to participate. Participation is simple and easy. Although the study is being conducted from the University of Utah and Johns Hopkins, anyone with five or more affected family members can participate regardless of where they live. All information gathered during the study will be numerically encoded so that the identities of the participants remain confidential. Thus far, more than 1,700 individuals have participated in this study.
Registering to participate in the Genetics of Strabismus Study
To determine if you qualify for participation in this study, please fill out the Strabismus Scorecard and email or fax it to Jenn Baird (information below). If you would like additional information about the study, please contact:
Jenn Baird
Genetic Research Coordinator
Eccles Institute of Human Genetics
University of Utah
15 North 2030 East
Building 533, Room 3160
Salt Lake City, Utah 84112
Office: (801) 585-1297
Fax: (801) 585-3501
Toll Free: 1-800-824-2073 ext. 5-1297 Email: jbaird@hmbg.utah.edu
Further information regarding strabismus
Strabismus, commonly known as crossed or lazy eye, is a condition in which both eyes cannot be aligned simultaneously under normal conditions. One or both eyes may turn in different directions. One eye may turn all of the time or only some of the time, usually under stressful situations or during illness.
It is currently thought that up to five percent of children have some degree of strabismus. Children with strabismus may initially experience double vision due to the misalignment of the eyes in relation to one another. To avoid double vision the brain will eventually ignore or suppress the image of one eye.
The following link may provide you with more information regarding strabismus and how you can help us find a cure. Click on the name of the disease above to visit the web page.
Parikh V, Shugart YY, Doheny KF, Zhang J, Li L, Williams J, Hayden D, Craig B, Capo H, Chamblee D, Chen C, Collins M, Dankner S, Fiergang D, Guyton D, Hunter D, Hutcheon M, Keys M, Morrison N, Munoz M, Parks M, Plotsky D, Protzko E, Repka MX, Sarubbi M, Schnall B, Siatkowski RM, Traboulsi E, Waeltermann J, Nathans J. A strabismus susceptibility locus on chromosome 7p. Proc Natl Acad Sci U S A. 2004 Mar 30;101(13):471-9.
Abstract: Strabismus has been known to have a significant genetic component, but the mode of inheritance and the identity of the relevant genes have been enigmatic. This paper reports linkage analysis of nonsyndromic strabismus. The principal results of this study are: (i) the demonstrated feasibility of identifying and recruiting large families in which multiple members have (or had) strabismus; (ii) the linkage in one large family of a presumptive strabismus susceptibility locus to 7p22.1 with a multipoint logarithm of odds score of 4.51 under a model of recessive inheritance; and (iii) the failure to observe significant linkage to 7p in six other multiplex families, consistent with genetic heterogeneity among families. These findings suggest that it will be possible to localize and ultimately identify strabismus susceptibility genes by linkage analysis and mutation screening of candidate genes.(full text pdf)
