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D.C. Chung1A, M.Matsumoto1A, N.Salem2, W.Lin1A, R.Wang1A, Q.Wang1B, Q.Chen1B, K.Zhang1A, A.Megarbane2, E.I. Traboulsi1A.
AOphthalmic Research, Cole Eye Institute,
BLerner Research Institute,
1Cleveland Clinic Foundation, Cleveland, OH;
2Unite de Genetique Medicale, Universite Saint-Joseph, Beirut, Lebanon.
Purpose: To map a chromosomal locus for autosomal dominant congenital posterior polar cataracts.
Methods: A four-generation Lebanese family with congenital posterior polar cataracts was identified. Forty members were examined and blood samples were collected for DNA extraction after informed consent was obtained. A genome-wide screen for the responsible locus was conducted using fluorescein-labelled microsatellite markers spaced at 10cM intervals. Genotyping was done and linkage analysis was performed. Two-point LOD scores were calculated using MLINK in LINKAGE version 5.2
Results: Twenty-one affected individuals were identified. Known loci for congenital cataracts were excluded. A significant positive LOD score of 3.56 at the recombination fraction of 0.00, was found with marker D10S2470 in the chromosomal 10q24-q26 region. D10S2470 is located in a 16 cM interval between markers D10S2327 and D10S677, both of which yielded negative LOD scores. The PITX3 gene maps to 10q24-q26 and it is responsible for one form of congenital cataracts. PITX3 was PCR-amplified from the proband, sequenced, and found not to harbor any mutations. Furthermore, the locus for PITX3 appears to be distinct from the locus of the cataract gene in this family.
Conclusion: An autosomal dominant congenital posterior polar cataract in a Lebanese family maps to the 10q24-q26 region. Studies are underway to further refine the locus and identify the responsible gene.
Commercial Relationship: D.C. Chung, None; M. Matsumoto, None; N. Salem, None; W. Lin, None; R. Wang, None; Q. Wang, None; Q. Chen, None; K. Zhang, None; A. Megarbane, None; E.I. Traboulsi, None.
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