Globally, CYP1B1 mutations in primary congenital glaucoma are strongly structured by geographic and haplotype backgrounds.
OBJECTIVE
To obtain a global perspective on the distribution and evolution of CYP1B1 mutations in primary congenital glaucoma (PCG) worldwide.


METHODS
Five intragenic single-nucleotide polymorphisms in CYP1B1-R48G, A119S, V432L, D449D, and N453S-were used to generate haplotype data from 138 Indian patients with PCG and 132 ethnically matched normal controls, which were then analyzed in conjunction with data from other populations. Maximum-likelihood estimates of haplotype frequencies were estimated from the genotype data. Subsets of patients and normal control subjects were also genotyped with respect to eight short tandem repeat (STR) markers around the CYP1B1 locus (D2S305, D2S165, D2S367, D2S2259, D2S391, D2S3337, D2S23678, and D2S286), to gain evolutionary insights.


RESULTS
Common mutations in CYP1B1 that are causal of PCG occurred on a uniform haplotype background among Indian patients, which is completely distinct from the modal haplotype background found among unaffected control subjects. Comparison of these data with data from other global regions reveals strong clustering of CYP1B1 mutations by geographic and haplotype backgrounds. The two distinct modal haplotypes found among Indian patients with PCG and control subjects are both ancient with ages of similar magnitudes, as indicated by large variances in the number of repeats at eight STR loci. Together with data from chimpanzee and normal control subjects from India and other global regions, it was possible to make a parsimonious reconstruction of the evolution of these haplotypes.


CONCLUSIONS
The strong association of specific haplotypes with some predominant CYP1B1 mutations underlying PCG and the observed geographical clustering, probably due to founder effects, may be useful for predictive testing.
Chakrabarti
Subhabrata
S
Kallam Anji Reddy Molecular Genetics Laboratory, L. V. Prasad Eye Institute, Hyderabad, India. subho@lvpei.org
Kaur
Kiranpreet
K
Kaur
Inderjeet
I
Mandal
Anil K
AK
Parikh
Rajul S
RS
Thomas
Ravi
R
Majumder
Partha P
PP
D000349:Africa; D017668:Age of Onset; D000569:Americas; D001189:Aryl Hydrocarbon Hydroxylases; D001208:Asia; D065633:Cytochrome P-450 CYP1B1; D003577:Cytochrome P-450 Enzyme System / Q000235:genetics*; D005060:Europe; D005819:Genetic Markers; D005901:Glaucoma / Q000151:congenital* / Q000208:ethnology / Q000235:genetics*; D006239:Haplotypes; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D016013:Likelihood Functions; D009154:Mutation; D020641:Polymorphism, Single Nucleotide
D005819:Genetic Markers; D003577:Cytochrome P-450 Enzyme System; D001189:Aryl Hydrocarbon Hydroxylases; C585496:CYP1B1 protein, human; D065633:Cytochrome P-450 CYP1B1