An insertion/deletion TEX28 polymorphism and its application to analysis of red/green visual pigment gene arrays.
TEX28 gene (fTEX) is present immediately downstream of the red/green visual pigment gene array on the human X chromosome. Its pseudogene (pTEX) that lacks exon 1 is present within the array between pigment genes. We found that both fTEX and pTEX genes had a 697 bp insertion/deletion polymorphism in their introns 3. In color-normal male subjects, the frequency of the 697 bp region was 43% (40/94) in pTEX and 97% (91/94) in fTEX in the array of Red-pTEX-Green-fTEX and 10% (9/94) in pTEX and 87% (41/47) in fTEX in the array of Red-pTEX-Green-pTEX-Green-fTEX. These results suggest that normal arrays with multiple green genes may have arisen through gene duplication rather than unequal homologous crossover. In color-vision-deficient male subjects with a single-gene array, the frequency of the 697 bp region was 83% (25/30) in the array of Green-fTEX and 66% (74/112) in the array of Red-fTEX. In color-vision-deficient male subjects with a 2-gene array, the frequency of the region was 44% (16/36) in pTEX and 97% (35/36) in fTEX in the array of Green-pTEX-Green-fTEX and 75% (18/24) in pTEX and 92% (22/24) in fTEX in the array of Red-pTEX-Red-fTEX. These results suggest that 2-green-gene arrays have arisen through unequal homologous crossover between a normal 2-gene array and a single-green-gene array. With data from a long-range PCR method using the insertion/deletion polymorphism, we proposed a structure of the second gene of 3-gene arrays, Green-pTEX-Green-pTEX-Green-fTEX and Red-pTEX-Red-pTEX-Red-fTEX, in color-vision-deficient subjects.
Ueyama
Hisao
H
Department of Medical Biochemistry, Shiga University of Medical Science, Seta, Otsu 520-2192, Japan. datt@belle.shiga-med.ac.jp.
Torii
Ryuzo
R
Research Center for Animal Life Science, Shiga University of Medical Science, Otsu, Japan.
Tanabe
Shoko
S
Institute of Visual Science, Nagoya, Japan.
Oda
Sanae
S
Department of Ophthalmology, Shiga University of Medical Science, Otsu, Japan.
Yamade
Shinichi
S
Department of Ophthalmology, Shiga University of Medical Science, Otsu, Japan.
D001483:Base Sequence; D041321:Chromosomes, Human, X; D003117:Color Vision Defects / Q000235:genetics*; D017931:DNA Primers; D004587:Electrophoresis, Agar Gel; D006801:Humans; D008297:Male; D008565:Membrane Proteins / Q000235:genetics*; D016254:Mutagenesis, Insertional; D016133:Polymerase Chain Reaction; D011110:Polymorphism, Genetic; D012168:Retinal Pigments / Q000235:genetics*; D017384:Sequence Deletion
D017931:DNA Primers; D008565:Membrane Proteins; D012168:Retinal Pigments; C108630:TEX28 protein, human