CYP3A phenotypes and genotypes in North Indians
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- Rais, N., Chawla, Y.K. & Kohli, K.K. Eur J Clin Pharmacol (2006) 62: 417. doi:10.1007/s00228-006-0105-3
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To phenotype 200 healthy North Indians for cytochrome P450 3A (CYP3A) activity by measuring urinary ratio of 6β-OH-cortisol/cortisol (6β-OH-CS/CS) and to genotype the subjects demonstrating low and high CYP3A activity for the presence of CYP3A4*1B, *2, *4, *5, *6 and *10 alleles.
Morning spot urine samples were collected from 200 healthy North Indians. CS and 6β-OH-CS were extracted and quantified by HPLC. Genotyping was performed by polymerase chain reaction (PCR) followed by restriction fragment length polymorphism (RFLP).
Urinary 6β-OH-CS/CS ratio demonstrated a mean of 52.0 ± 46 (1.1–290). North Indians demonstrated unimodal distribution with respect to urinary 6β-OH-CS/CS ratio. On the basis of phenotypes, the subjects were divided into three groups demonstrating low (n=50), intermediate (n=100) and high (n=50) CYP3A activity. These groups demonstrated 6β-OH-CS/CS ratio of 13.4 ± 5.2 (1.1–21.0), 40 ± 11.9 (21.2–63.2) and 114 ± 51.0 (66–290), respectively. One hundred subjects, 50 in the low and 50 in the high activity group, were genotyped for CYP3A4*1B, *2, *4, *5, *6 and *10. Only 2 heterozygotes with genotype CYP3A4*1/*1B were found in the high CYP3A activity group. CYP3A4*2, *4, *5, *6 and *10 were not found in the subjects studied.
This is the first investigation establishing CYP3A phenotypes and demonstrating the absence of common CYP3A4 genotypes in North Indians.