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Daniel K. Roberts, Radha Ayyagari, Bridget J. McCarthy, Hui Xie, Jacob T. Wilensky, Faye Davis; Case-Control Study of Long Anterior Lens Zonule (LAZ) Trait in First-Degree Relatives of African-American Probands. Invest. Ophthalmol. Vis. Sci. 2011;52(14):2800.
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The long anterior zonule (LAZ) trait is characterized by zonular fibers that insert more central than usual on the anterior lens capsule. LAZ may cause a unique type of intraocular pigment dispersion, and there is question whether there is association with open- and narrow-angle forms of glaucoma. Although LAZ can be familial in conjunction with a complex phenotype of LAZ and late-onset retinal degeneration (L-ORD) resulting from a C1QTNF5/CTRP5 mutation in white families, the trait does not appear to have genetic homogeneity. This study evaluated familial aggregation apart from a L-ORD association.
African-American LAZ, probable LAZ, and control probands (matched on race, age) and first-degree relatives had a complete eye exam, including ocular/medical history, EOM testing, color vision testing, pupil testing, refraction, Goldmann tonometry, gonioscopy, dilated fundus exam, and threshold visual fields. Testing was done as part of a larger investigation to study ocular and medical parameters associated with LAZ, and the analysis included 37 first-degree relatives (2 parents, 15 siblings, 20 children) belonging to 25 LAZ probands (mean age=68.8 + 9.0 yrs), 21 first-degree relatives (14 siblings, 7 children) belonging to 11 probable LAZ probands (69.2 + 8.6 yrs), and 36 first-degree relatives (14 siblings, and 22 children) belonging to 22 control probands (66.7 + 9.3 yrs). Logistic regression was used to compare LAZ prevalence among case/control relatives.
LAZ were detected in 10 of 37 (27.0%) LAZ relatives, 4 of 21 (19.0%) probable LAZ relatives, and 2 of 36 (5.6%) control relatives. Based on these data, the LAZ trait was 6.3 times more likely (OR=6.3; 95% CI=1.3 to 31.2; P=0.02) to occur among first-degree relatives of LAZ probands than of controls. Combining the definite and probable LAZ families, the LAZ trait was 5.4 times more likely (OR=5.4; 95% CI=1.2 to 25.4; P=0.03) to occur among relatives of LAZ probands than of controls.
The LAZ trait was significantly more likely to be detected in first-degree relatives of African-American LAZ probands than among relatives of comparable controls. This is consistent with the possibility of a genetic etiology for the trait among African-Americans who do not have the L-ORD phenotype.
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