Comparative analysis of common CFTR polymorphisms poly-T, TG-repeats and M470V in a healthy Chinese population.
OBJECTIVE
To investigate the three important cystic fibrosis transmembrane conductance regulator (CFTR) haplotypes poly-T, TG-repeats and the M470V polymorphisms in the Chinese population, and to compare their distribution with that in Caucasians and other Asian populations.


METHODS
Genomic DNA was extracted from blood leukocytes. Exons 9 and 10 of the CFTR gene were obtained through polymerase chain reaction (PCR). Exon 9 DNA sequences were directly detected by an automated sequencer and poly-T and TG-repeats were identified by direct sequence analysis. Pure exon 10 PCR-amplified products were digested by HphI restriction enzyme and the M470V mutation was detected by the AGE photos of digestion products.


RESULTS
T7 was the most common (93.6%) haplotype and the (TG)11 frequency of 57.2% and (TG)12 frequency of 40.9% were dominant haplotypes in the junction of intron 8 (IVS-8) and exon 9. The frequency of T5 was 3.8% and all T5 allele tracts (10 alleles) were joined with (TG)12. Four new alleles of T6 (1.5%) were found in three healthy individuals. In exon 10, the V allele (56.1%) was slightly more frequent than the M allele (43.9%), and the M/V (45.5%) was the dominant genotype in these individuals. The three major haplotypes T7-(TG)11-V470, T7-(TG)12-M470 and T7-TG11-M470 were related to nearly 86.0% of the population.


CONCLUSIONS
The polymorphisms of poly-T, TG-repeats, and M470V distribution were similar to those in other East Asians, but they had marked differences in frequency from those single haplotype polymorphisms or linkage haplotypes in Caucasians. Thus, they may be able to explain the low incidence of CF and CF-like diseases in Asians.
Huang
Qin
Q
Department of Traditional Chinese Medicine, the First Affiliated Hospital of Nanjing Medical University, 300 Guangzhou Road, Nanjing 210029, Jiangsu Province, China.
Ding
Wei
W
Wei
Mu-Xin
MX
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000483:Alleles; D044466:Asian People / Q000235:genetics; D002681:China; D019005:Cystic Fibrosis Transmembrane Conductance Regulator / Q000235:genetics*; D004252:DNA Mutational Analysis; D005260:Female; D005787:Gene Frequency; D006239:Haplotypes; D006801:Humans; D008297:Male; D008875:Middle Aged; D011110:Polymorphism, Genetic; D011897:Random Allocation; D044465:White People / Q000235:genetics
C505032:CFTR protein, human; D019005:Cystic Fibrosis Transmembrane Conductance Regulator