title: A novel MIP gene mutation analysis in a Chinese family affected with congenital progressive punctate cataract.
abstract: Congenital cataracts are one of the leading causes of visual impairment and blindness in children, and genetic factors play an important role in their development. This study aimed to identify the genetic defects associated with autosomal dominant congenital progressive punctate cataracts in a Chinese family and to explore the potential pathogenesis. Detailed family history and clinical data were recorded, and all the family members' blood samples were collected for DNA extraction. Linkage analysis was performed by microsatellite markers that are associated with punctate cataracts, and logarithm (base 10) of odds (LOD) scores were calculated using the LINKAGE program. Positive two-point LOD scores were obtained at markers D12S1622 (Zmax = 2.71 at θ = 0.0), D12S1724 (Zmax = 2.71 at θ = 0.0), and D12S90 (Zmax = 2.71 at θ = 0.0), which flank the major intrinsic protein of lens fiber (MIP) gene on chromosomal region 12q13. Direct sequencing of the encoding region of the MIP gene revealed a novel mutation (G>D) in exon 4 at nucleotide 644, which caused a substitution of glycine to aspartic acid at codon 215 (p.G215D) for the MIP protein. The mutation cosegregated with all patients with congenital progressive punctate cataracts, but it was absent in the healthy members. Bioinformatics analysis predicted that the mutation affects the function of the MIP protein. The wild type (WT) and G215D mutant of MIP were transfected with green fluorescent protein (GFP) into Hela cells separately, and it was found that the G215D mutant was aberrantly located in the cytoplasm instead of in the plasma membrane. In summary, our study presented genetic and functional evidence linking the new MIP mutation of G215D to autosomal dominant congenital cataracts, which adds to the list of MIP mutations linked to congenital progressive punctate cataracts.
authors.affiliation: Department of Ophthalmology, The Second Affiliated Hospital of Harbin Medical University, Harbin, China.
authors.forename: Xuchen
authors.initials: X
authors.lastname: Ding
authors.affiliation: Department of Ophthalmology, The Second Affiliated Hospital of Harbin Medical University, Harbin, China.
authors.forename: Nan
authors.initials: N
authors.lastname: Zhou
authors.affiliation: Department of Ophthalmology, The Second Affiliated Hospital of Harbin Medical University, Harbin, China.
authors.forename: Hui
authors.initials: H
authors.lastname: Lin
authors.affiliation: Department of Ophthalmology, Shanghai Tenth People's Hospital and Tongji Eye Institute, Tongji University School of Medicine, Shanghai, China; Ophthalmic Genetics and Visual Function Branch, National Eye Institute, National Institutes of Health, Bethesda, Maryland, United States of America.
authors.forename: Jianjun
authors.initials: J
authors.lastname: Chen
authors.affiliation: Department of Ophthalmology, The Second Affiliated Hospital of Harbin Medical University, Harbin, China.
authors.forename: Chunyuan
authors.initials: C
authors.lastname: Zhao
authors.affiliation: Department of Ophthalmology, The Second Affiliated Hospital of Harbin Medical University, Harbin, China.
authors.forename: Guangkai
authors.initials: G
authors.lastname: Zhou
authors.affiliation: Ophthalmic Genetics and Visual Function Branch, National Eye Institute, National Institutes of Health, Bethesda, Maryland, United States of America.
authors.forename: J Fielding
authors.initials: JF
authors.lastname: Hejtmancik
authors.affiliation: Department of Ophthalmology, The Second Affiliated Hospital of Harbin Medical University, Harbin, China.
authors.forename: Yanhua
authors.initials: Y
authors.lastname: Qi
mesh_terms: D020346:Aquaporins / Q000235:genetics*; D044466:Asian People / Q000235:genetics*; D002386:Cataract / Q000235:genetics*; D002460:Cell Line; D045744:Cell Line, Tumor; D004252:DNA Mutational Analysis / Q000379:methods; D005091:Exons / Q000235:genetics; D005136:Eye Proteins / Q000235:genetics*; D005260:Female; D005799:Genes, Dominant / Q000235:genetics; D008040:Genetic Linkage / Q000235:genetics; D057809:HEK293 Cells; D006367:HeLa Cells; D006801:Humans; D007908:Lens, Crystalline / Q000473:pathology; D008126:Lod Score; D008297:Male; D018895:Microsatellite Repeats / Q000235:genetics; D009154:Mutation / Q000235:genetics*; D010375:Pedigree
chemical_list: D020346:Aquaporins; D005136:Eye Proteins; C030328:aquaporin 0