Abstract
Abstract: :
Purpose: To map and identify the gene for ADC in a Peruvian family. Methods: ADC 45, a four generation Peruvian family with seven affected individuals, was studied for linkage. Affected members had embryonal cataracts varying from punctuate, white opacities to dense white opacification. SIMLINK was used to estimate the power to detect linkage in this pedigree. Our screening panel of ADC loci was used to exclude known loci. PCR amplification was preformed separately for each primer and processed on an ABI 373 using Genescan 2.1 software (Applied Biosystems). LOD scores were calculated using LIPED. Results: For a tightly linked marker, we estimated that linkage analysis in this family will have 52% power to detect a LOD greater than 2; the maximum LOD score achieved over 1000 simulations was 2.96. LOD scores were calculated for markers on chromosomes 1, 2, 10, 11, 12, 13, 15, 16, 17, 19, 20, 21, and 22. There is no evidence of co-segregation except for chromosome 11. Screening markers D11S4176 and D11S4175 on chromosome 11 suggested linkage based on LOD scores of 0.90 and 1.80, respectively. Conclusion: Using our ADC screening panel, we excluded linkage in this family with all markers known to be linked to human ADC except those on chromosome 10, 21, and 11; we identified possible linkage of ADC 45 on chromosome 11. A candidate gene in this area is alpha-B crystallin gene (CRYAB). Mutations in CRYAB have been shown to cause dominant congenital posterior polar cataract in humans. We will continue mapping in the q14.3 area of chromosome 11 to find additional informative markers, refine localization and then sequence candidate genes. The clinical features in our family differ from the reported family with a CRYAB mutation.
Keywords: cataract • gene mapping