Analysis of single nucleotide polymorphisms of CRYGA and CRYGB genes in control population of western Indian origin.
OBJECTIVE
Polymorphisms in gamma-crystallins ( CRYG ) can serve as markers for lens differentiation and eye disorders leading to cataract. Several investigators have reported the presence of sequence variations within crystallin genes, with or without apparent effects on the function of the proteins both in mice and humans. Delineation of these polymorphic sites may explain the differences observed in the susceptibility to cataract observed among various ethnic groups. An easier Restriction Fragment Length Polymorphism (RFLP)-based method has been used to detect the frequency of four single nucleotide polymorphisms (SNPs) in CRYGA / CRYGB genes in control subjects of western Indian origin.


METHODS
A total of 137 healthy volunteers from western India were studied. Examination was performed to exclude volunteers with any ocular defects. Polymerase chain reaction (PCR)-RFLP based method was developed for genotyping of G198A (Intron A), T196C (Exon 3) of CRYGA and T47C (Promoter), G449T (Exon 2) of CRYGB genes.


RESULTS
The exonic SNPs in CRYGA and CRYGB were found to have an allele frequency 0.03 and 1.00 for ancestral allele respectively, while frequency of non-coding SNP in CRYGA was 0.72. Allele frequency of T90C of CRYGB varied significantly ( P = 0.02) among different age groups. An in-silico analysis reveals that this sequence variation in CRYGB promoter impacts the binding of two transcription factors, ACE2 (Member of CLB2 cluster) and Progesterone Receptor (PR) which may impact the expression of CRYGB gene.


CONCLUSIONS
This study establishes baseline frequency data for four SNPs in CRYGA and CRYGB genes for future case control studies on the role of these SNPs in the genetic basis of cataract.
Kapur
Suman
S
Birla Institute of Technology and Science, Pilani - 333 031, Rajasthan, India. s_kapur@bits-pilani.ac.in
Mehra
Shipra
S
Gajjar
Devarshi
D
Vasavada
Abhay
A
Kapoor
Manav
M
Sharad
Shashwat
S
Alapure
Bhagwat
B
Rajkumar
S
S
D000293:Adolescent; D000328:Adult; D000368:Aged; D002386:Cataract / Q000235:genetics; D002648:Child; D002675:Child, Preschool; D005260:Female; D005787:Gene Frequency; D005828:Genetics, Population; D005838:Genotype; D006801:Humans; D007194:India; D007438:Introns / Q000235:genetics; D008297:Male; D008875:Middle Aged; D016133:Polymerase Chain Reaction; D012150:Polymorphism, Restriction Fragment Length; D020641:Polymorphism, Single Nucleotide; D038222:gamma-Crystallins / Q000235:genetics*
D038222:gamma-Crystallins