Purpose: To study the correlation of genotype for X-linked red-green gene array with color vision phenotype in 58 subjects with red-green color vision deficiency. Methods: The molecular structure of red and green pigment genes on 58 X chromosomes was studied exon-by-exon by using heteroduplex-SSCP analysis and sequencing. The color vision of these subjects was determined by a Neitz anomaloscope. Results: Variations in the red and green pigment genes were detected in 43 subjects and a hybrid gene was found in 27 subjects. About 50% of the fusion sites occurred at intron 2-3. All 3 anomalous trichromats with intron 4 fusion were mild type but another 3 with intron 2-3 fusion were severe type. No subjects with mild type of color vision defects had a fusion site at intron 2-3 or its upstream. Three subjects with complete deletion of the green pigment gene manifested deuteranomaly. Conclusions: Protans can be differentiated from deutans on the basis of genotype. It is still difficult to establish a clear correlation of different anomalous trichromats with genotype. The fusion site of a hybrid gene affects the phenotype to some degree. Intron 2-3 is the common place for gene crossover.

Purpose: To screen for possible disease-causing mutations in the CRX gene in Chinese patients with Leber congenital amaurosis (LCA) and to enrich the understanding of its mutational phenotype. Methods: Genomic DNA was collected from 27 patients with LCA.The coding sequences of the CRX gene were analyzed using the PCRheteroduplex-SSCP method. Mutations were confirmed by DNA sequencing. Results: We identified two heterozygous variations in the CRX gene in two patients with LCA. One was a deletion (GCCÆ-CC, A181D1bp) leading to a frameshift and protein truncation. This mutation was present in a patient with LCA, but not in his healthy parents. The ocular manifestations of this A181D1bp mutation are described. An intronic variation (IVS1-13G→C) was found in a patient with LCA as well as in his healthy father. Conclusion: A heterozygous A181D1bp mutation in the CRX gene caused an LCA phenotype in a Chinese patient.

Bietti crystalline corneoretinal dystrophy (BCD) is an autosomal recessive retinal dystrophy characterized by multiple glistening intraretinal crystals scattered over the fundus, a characteristic degeneration of the retina, and sclerosis of the choroidal vessels, ultimately resulting in progressive night blindness and constriction of the visual field. The BCD region of chromosome 4q35.1 was refined to an interval flanked centromerically by D4S2924 by linkage and haplotype analysis; mutations were found in the novel CYP450 family member CYP4V2 in 23 of 25 unrelated patients with BCD tested. The CYP4V2 gene, transcribed from 11 exons spanning 19 kb, is expressed widely. Homology to other CYP450 proteins suggests that CYP4V2 may have a role in fatty acid and steroid metabolism, consistent with biochemical studies of patients with BCD.

PURPOSE. To identify the disease locus of autosomal recessive congenital nuclear cataracts in a consanguineous Pakistani family. METHODS. A large Pakistani family with multiple individuals affected by autosomal recessive congenital cataracts was ascertained. Patients were examined, blood samples were collected, and DNA was isolated. A genome-wide scan was performed using 382 polymorphic microsatellite markers on genomic DNA from affected and unaffected family members. Two-point lod scores were calculated, and haplotypes were formed by inspection. RESULTS. In the genome-wide scan, a maximum lod score of 2.89 was obtained for marker D19S414 on 19q13. Fine mapping using D19S931, D19S433, D19S928, D19S225, D19S416, D19S213, D19S425, and D19S220 markers from the Généthon database showed that markers in a 14.3-cM (12.66-Mb) interval flanked by D19S928 and D19S420 cosegregated with the cataract locus. Lack of homozygosity further suggests that the cataract locus may lie in a 7-cM (4.3-Mb) interval flanked by D19S928 proximally and D19S425 distally. On fine mapping, a maximum lod score of 3.09 was obtained with D19S416 at θ=0. CONCLUSIONS. Linkage analysis identified a new locus for autosomal recessive congenital nuclear cataracts on chromosome 19q13 in a consanguineous Pakistani family.

URPOSE. To identify the disease locus for autosomal recessive congenital cataracts in consanguineous Pakistani families. METHODS. Two Pakistani families were ascertained, patients were examined, blood samples were collected, and DNA was isolated. A genome-wide scan was performed using 382 polymorphic microsatellite markers on genomic DNA from affected and unaffected family members. Two-point lod scores were calculated, haplotypes were formed by inspection, and candidate genes were sequenced. Real-time quantitative PCR techniques were used to determine the mRNA levels, and molecular modeling was performed to gain a better understanding of the significance of the disease-causing mutation. RESULTS. In the genome-wide scan, maximum lod scores of 2.67 and 2.77 for family 60004 and 2.02 and 2.04 for family 60006 were obtained for markers D22S539 and D22S315, respectively. The linked region, 22.7 cM (10 Mb) flanked by markers D22S420 and D22S1163, contains the-crystallin gene cluster including the genes CRYBA4, CRYBB1, CRYBB2, and CRYBB3. Sequencing of these genes showed a G3C transition in exon 6 of CRYBB3 resulting in a p.G165R change in the B3-crystallin protein that cosegregates with the disease in both families. Real-time PCR analysis suggested that βB3-crystallin mRNA levels approximate those of other βγ-crystallins. Molecular modeling predicted changes in electrostatic potential that would be expected to reduce the stability of the fourth Greek-key motif, and hence the entire protein, dramatically. CONCLUSIONS. For the first time, a mutation in CRYBB3 is reported in two consanguineous Pakistani families with autosomal recessive congenital cataracts. (Invest Ophthalmol Vis Sci. 2005;46:2100–2106) DOI:10.1167/iovs.04-148