Search

Purpose: To investigate the genetic basis of autosomal recessive congenital cataracts (arCC) in a large consanguineous Pakistani family., Methods: All participating members of family, PKCC074 underwent an ophthalmic examination. Slit-lamp photographs were ascertained for affected individuals that have not been operated for the removal of the cataractous lens. A small aliquot of the blood sample was collected from all participating individuals and genomic DNAs were extracted. A genome-wide scan was performed with polymorphic short tandem repeat (STR) markers and the logarithm of odds (LOD) scores were calculated. All coding exons and exon-intron boundaries of HSF4 were sequenced and expression of Hsf4 in mouse ocular lens was investigated. The C-terminal FLAG-tagged wild-type and mutant HSF4b constructs were prepared to examine the nuclear localization pattern of the mutant protein., Results: The ophthalmological examinations suggested that nuclear cataracts are present in affected individuals. Genome-wide linkage analyses localized the critical interval to a 10.95 cM (14.17 Mb) interval on chromosome 16q with a maximum two-point LOD score of 4.51 at θ = 0. Sanger sequencing identified a novel missense mutation: c.433G>C (p.Ala145Pro) that segregated with the disease phenotype in the family and was not present in ethnically matched controls. Real-time PCR analysis identified the expression of HSF4 in mouse lens as early as embryonic day 15 with a steady level of expression thereafter. The immunofluorescence tracking confirmed that both wild-type and mutant HSF4 (p.Ala145Pro) proteins localized to the nucleus., Conclusion: Here, we report a novel missense mutation in HSF4 associated with arCC in a familial case of Pakistani descent., Competing Interests: The authors have declared that no competing interests exist.

Purpose: The purpose of this study was to study the molecular basis of inherited autosomal recessive cataracts in Pakistan population and to identify the molecular defect segregating with the disease phenotype., Methods: Families having two or more affected individuals were identified through hospital, blood samples were collected and DNA was extracted. We employed the traditional strategy of linkage analysis using M13-labeled primers to map the already known genes for autosomal recessive cataract. Statistically, the data were evaluated through LOD score., Results: Ten families affected with autosomal receive congenital cataract were enrolled for this study. Overall, three families were linked to reported loci for autosomal recessive congenital cataract. Out of these, one family Bl05 was linked to a cataract locus at 9q13. Fine mapping of the chromosome 9 locus considerably delimited the previously reported linkage interval from 13.99 to 7.99 cM in this study., Conclusion: Our results reduced the linkage interval of previously reported cataract locus on chromosome 9, thus considerably reducing the number of candidate genes.

Purpose: To identify the molecular basis of non-syndromic autosomal recessive congenital cataracts (arCC) in a consanguineous family., Methods: All family members participating in the study received a comprehensive ophthalmic examination to determine their ocular phenotype and contributed a blood sample, from which genomic DNA was extracted. Available medical records and interviews with the family were used to compile the medical history of the family. The symptomatic history of the individuals exhibiting cataracts was confirmed by slit-lamp biomicroscopy. A genome-wide linkage analysis was performed to localize the disease interval. The candidate gene, LIM2 (lens intrinsic membrane protein 2), was sequenced bi-directionally to identify the disease-causing mutation. The physical changes caused by the mutation were analyzed in silico through homology modeling, mutation and bioinformatic algorithms, and evolutionary conservation databases. The physiological importance of LIM2 to ocular development was assessed in vivo by real-time expression analysis of Lim2 in a mouse model., Results: Ophthalmic examination confirmed the diagnosis of nuclear cataracts in the affected members of the family; the inheritance pattern and cataract development in early infancy indicated arCC. Genome-wide linkage analysis localized the critical interval to chromosome 19q with a two-point logarithm of odds (LOD) score of 3.25. Bidirectional sequencing identified a novel missense mutation, c.233G>A (p.G78D) in LIM2. This mutation segregated with the disease phenotype and was absent in 192 ethnically matched control chromosomes. In silico analysis predicted lower hydropathicity and hydrophobicity but higher polarity of the mutant LIM2-encoded protein (MP19) compared to the wild-type. Moreover, these analyses predicted that the mutation would disrupt the secondary structure of a transmembrane domain of MP19. The expression of Lim2, which was detected in the mouse lens as early as embryonic day 15 (E15) increased after birth to a level that was sustained through the postnatal time points., Conclusion: A novel missense mutation in LIM2 is responsible for autosomal recessive congenital cataracts., Competing Interests: The authors have declared that no competing interests exist.

Purpose: To identify the disease locus for autosomal recessive congenital cataracts in a consanguineous Pakistani family., Methods: All affected individuals underwent a detailed ophthalmologic examination. Blood samples were collected and genomic DNA was extracted. A genome-wide scan was completed with fluorescently-labeled microsatellite markers on genomic DNA from affected and unaffected family members. Logarithms of odds (LOD) scores were calculated under a fully penetrant autosomal recessive model of inheritance., Results: Ophthalmic examination suggested that affected individuals have bilateral cataracts. Linkage analysis localized the critical interval to chromosome 8p with LOD scores of 3.19, and 3.08 at θ=0, obtained with markers D8S549 and D8S550, respectively. Haplotype analyses refined the critical interval to 37.92 cM (16.28 Mb) region, flanked by markers, D8S277 proximally and D8S1734 distally., Conclusions: Here, we report a new locus for autosomal recessive congenital cataract mapped to chromosome 8p in a consanguineous Pakistani family.

Purpose: To identify the pathogenic mutations responsible for autosomal recessive congenital cataracts in consanguineous Pakistani families., Methods: All affected individuals underwent detailed ophthalmologic and medical examination. Blood samples were collected and genomic DNA was extracted. A genome-wide scan was performed with polymorphic microsatellite markers on genomic DNA from affected and unaffected family members and logarithm of odds (LOD) scores were calculated. All coding exons of galactokinase (GALK1) were sequenced to identify pathogenic lesions., Results: Clinical records and ophthalmological examinations suggested that affected individuals have nuclear cataracts. Linkage analysis localized the critical interval to chromosome 17q with a maximum LOD score of 5.54 at theta=0, with D17S785 in family PKCC030. Sequencing of GALK1, a gene present in the critical interval, identified a single base pair deletion: c.410delG, which results in a frame shift leading to a premature termination of GALK1: p.G137fsX27. Additionally, we identified a missense mutation: c.416T>C, in family PKCC055 that results in substitution of a leucine residue at position 139 with a proline residue: p.L139P, and is predicted to be deleterious to the native GALK1 structure., Conclusions: Here, we report pathogenic mutations in GALK1 that are responsible for autosomal recessive congenital cataracts in consanguineous Pakistani families.

Purpose: To investigate the genetic basis of autosomal recessive congenital cataracts in a consanguineous Pakistani family., Methods: All affected individuals underwent a detailed ophthalmological and clinical examination. Blood samples were collected and genomic DNAs were extracted. A genome-wide scan was performed with polymorphic microsatellite markers. Logarithm of odds (LOD) scores were calculated, and Eph-receptor type-A2 (EPHA2), residing in the critical interval, was sequenced bidirectionally., Results: The clinical and ophthalmological examinations suggested that all affected individuals have nuclear cataracts. Genome-wide linkage analyses localized the critical interval to a 20.78 cM (15.08 Mb) interval on chromosome 1p, with a maximum two-point LOD score of 5.21 at theta=0. Sequencing of EPHA2 residing in the critical interval identified a missense mutation: c.2353G>A, which results in an alanine to threonine substitution (p.A785T)., Conclusions: Here, we report for the first time a missense mutation in EPHA2 associated with autosomal recessive congenital cataracts.

Purpose: To identify the disease locus for autosomal recessive congenital cataract in a consanguineous Pakistani family., Methods: All affected individuals underwent detailed ophthalmologic and medical examination. Blood samples were collected and DNA was extracted. A genome-wide scan was performed with polymorphic microsatellite markers on genomic DNA from affected and unaffected family members, and logarithm of odds (LOD) scores were calculated., Results: The clinical records and ophthalmological examinations suggested that all affected individuals have nuclear cataracts. Maximum LOD scores of 5.01, 4.38, and 4.17 at theta=0 were obtained with markers D7630, D7S657, and D7S515, respectively. Fine mapping refined the critical interval and suggested that markers in a 27.78 cM (27.96 Mb) interval are flanked by markers D7S660 and D7S799, which co-segregate with the disease phenotype in family PKCC108., Conclusions: We have identified a new locus for autosomal recessive congenital cataract, localized to chromosome 7q21.11-q31.1 in a consanguineous Pakistani family.

Purpose: To identify the disease locus for autosomal recessive congenital cataracts in two consanguineous Pakistani families., Methods: Two Pakistani families were ascertained, ophthalmologic examination including slit lamp biomicroscopy was performed on all members, blood samples were collected and DNA was extracted. A genome-wide scan was performed using 382 polymorphic microsatellite markers on genomic DNA from affected and unaffected family members. Two-point logarithm of odds (LOD) scores were calculated using the LINKAGE program package., Results: All the affected individuals of family PKCC009 show bilateral membranous cataract, whereas the affected individuals of family PKCC039 show bilateral posterior sub-capsular cataract. Other ocular abnormalities include corneal opacities, microcornea and nystagmus in the affected individuals of PKCC009. Maximum two point LOD scores were obtained with D1S186 (4.14 at theta = 0), D1S432 (4.01 at theta = 0), D1S2892 (4.11 at theta = 0), and D1S2797 (4.07 at theta = 0) for family PKCC009 and with D1S496 (4.73 at theta = 0), D1S2892 (4.34 at theta = 0), D1S3721 (4.83 at theta = 0), and D1S2797 (4.32 at theta = 0) for family PKCC039. The common linked region, 20.76 cM (20.80 Mb), is flanked by markers D1S2729 and D1S2890 and co-segregates with the disease in both families, placing the disease locus on chromosome 1p34.3-p32.2., Conclusions: Linkage analysis of autosomal recessive cataracts in two consanguineous Pakistani families localizes a novel locus for autosomal recessive congenital cataract on chromosome 1p.