( itbl ) are 
 often used as synonyms for hilar or intrahepatic diffuse bile duct strictures , 
 necrosis , ecstasies , or dilatations ( see figure 1 ) [ 1 , 2 ] . the reported 
 incidence of itbl after olt varies between 1.4% and 20% [ 35 ] . this complication encounters for major morbidity and mortality , creates high 
 costs , and aggravates organ shortage [ 7 , 8 ] . a recent study on 1113 liver transplant patients showed 
 no relevant donor or recipient risk factor of itbl . there are only 
 two studies evaluating the impact of chemokine receptors ( ccr ) on the 
 development of itbl [ 6 , 9 ] . in moench 's study on 146 olt patients ccr-532 mutation was evaluated and correlated 
 with a significant increased incidence of itbl . a recent study on 
 137 pediatric liver transplants failed to show an association between ccr-532 and biliary complications . ccr-532 is a single base - pair deletion of ccr-5 that 
 leads to a nonfunctional receptor . the clinical impact of this 
 mutation was first described for homozygous ccr-532 caucasians being highly resistant to hiv-1 
 infection . if there was an immunological cause for itbl , a 
 nonfunctional ccr might be relevant for this complication . experimental studies correlated a 
 nonfunctional ccr-5 with less acute rejection episodes in lung , heart   and islet cell transplantation . the aim of this study was to re - examine a 
 correlation of ccr-532 genotype with the susceptibility of itbl 
 within our patients . all patients were transplanted at the transplant center of the 
 humboldt university of berlin between 03/2002 and 03/2005 and were included 
 during routine follow - up examination . 11 patients with the established diagnosis of itbl , that were transplanted 
 earlier than 03/2001 , were selectively included into this study due to the low 
 incidence of itbl of only 4.0% within our patients . the diagnosis of itbl was 
 made within the first year after transplantation in 82% of the patients . the 
 following demographic data were extracted from the hospital records and 
 evaluated : age , gender , underlying liver disease , blood group , child - pugh score 
 ( cps ) , model for end stage liver disease score ( meld score ) , initial 
 immunosuppression , cytomegalovirus infection ( cmv ) , hla match , donor age and 
 gender , donor serum sodium , cause of brain death and length of stay on 
 intensive care unit ( icu ) prior to organ harvesting . 154 patients received a 
 cadaver graft , 15 patients received a graft from a living donor . itbl was defined as nonanastomotic intra- or 
 extrahepatic biliary strictures without any history of hepatic artery 
 complications , abo , incompatibility or other known causes of bile duct damages . 
 in all cases patency of the hepatic artery recurrence 
 of primary biliary cirrhosis ( pbc ) or primary sclerosing cholangitis ( psc ) and 
 vanishing bile duct syndrome were ruled out in all cases by liver biopsy . diagnosis of itbl was always established with endoscopic retrograde 
 cholangiography or percutaneous transhepatic cholangiography . all 
 genotype analyses were performed at the johannes gutenberg university of mainz , 
 department of transplantation surgery . for analysis of the ccr-5 genotype , genomic dna was prepared from 200 l peripheral blood using the qiaamp dna blood 
 kit ( qiagen , cologne , germany ) . 2.5 l of dna were amplified by pcr using the 
 following ccr-5 specific primers : ccr - sense , 5-caaaaagaaggtcttcattacacc-3 
 and ccr-5-antisense , 5-cctgtgcctcttcttctcatttcg-3. the pcr mixture was 
 composed of 2.5 l 10 x pcr buffer ( roche molecular systems , 
 mannheim , germany ) , 0.5 l of 12.5 mmol / l dntp ( peqlab , erlangen , 
 germany ) , 2.5 l of each sense and antisense primer ( 10 mol / l ) , and 1.25 u amplitag dna polymerase 
 ( roche molecular systems ) in a total volume of 25 l . forty pcr cycles were run on a genius 
 thermocycler ( techne , cambridge , uk ) , using the following temperature profile : 
 initial denaturation , 94c 3 minutes ; amplification , 94c 1 minute , 64c 1 
 minute , and , 72c 1 minute ( 40 cycles ) ; terminal elongation , 72c 9 minutes . the size 
 of the wild - type product was 189 base pairs ( bp ) , and the ccr-532 allele yielded a product of 157 bp . descriptive statistics 
 were used to summarize the donor and recipients characteristics . for 
 independent variables , cross tabulations and chi - square tests were performed . nonparametric variables were evaluated with fisher 's exact test ,   and asymptotic 
 significance was calculated . all 
 calculations were performed in association with the department of biometrical 
 medicine of the humboldt university of berlin . a total 
 number of 169 liver transplant recipients were available for genotyping and 
 complete data analysis . gender and age were equally distributed between 
 wild - type group ( wt / wt ) and heterozygous ccr-532 group ( wt/32 ) . the observed genotype 
 frequency was as expected assessed by hardy - weinberg equilibrium in the study 
 population . there were no differences between wt / wt group and wt/32 group regarding to cps score , meld score or 
 blood group ( table 1 ) . there were 
 no statistical significant differences in the composition of underlying liver 
 disease of group wt / wt and wt/32 . initial 
 immunosuppression was tacrolimus based in 82.6% in the wt / wt group compared to 
 84.8% in the wt/32 group . cmv infection 
 that demanded ganciclovir treatment was present in approximately 30% in the 
 wt / wt and wt/32 group and in both homozygous patients . donors of group 32/32 were younger ( 35.7 years versus 46.5 years and 
 48.5 years ) . mmol / l in the wt/32 group and 155.5 mmol / l in the 32/32 group . data of causes of brain death and 
 length of stay on the icu prior to organ harvesting are shown in table 2 . incidence 
 of itbl was 11.2% in this study due to the selection of patients with itbl that 
 were additionally included into this evaluation . homozygous 32 patients developed no itbl compared to 11.2% 
 and 12.1% of homozygous wild - type patients and heterozygous patients , 
 respectively . the rate of retransplantation was 3.0% in both wt / wt and wt/32 group ( see table 3 ) . retransplantation of 
 the heterozygous patient was indicated due to chronic ductopenic rejection 
 following olt for psc . in the wt / wt group , the 
 problem of genetic association studies and complex clinical syndromes or 
 diseases must be addressed . one can always question the usefulness of these 
 studies that    are often    even small in sample size . , it seems important to undertake 
 replication studies for reported associations between genetic polymorphisms and 
 diseases , especially in diseases of major clinical importance . in this 
 study , the distribution of heterozygous 32 and homozygous 32 mutation was very consistent with   the 
 published data of the global distribution of this gene polymorphism [ 10 , 16 ] . heterozygous and homozygous genotypes occur 
 in caucasian population in 15%20% and 1% , respectively . this seems 
 important due to the small number of patients included in this study and the 
 possible bias by including selected patients with the diagnosis of itbl into 
 the study cohort . despite 
 increasing success rates in clinical olt over the past decades , itbl remains a 
 major cause for recipient morbidity and mortality [ 15 ] . up till 
 today , only risk factors for itbl could be identified in various clinical 
 studies . the length of cold ischemic time was correlated with the development 
 of itbl [ 14 ] . immunological causes seem to play only a minor role in the pathogenesis of 
 itbl . described a single base - pair deletion in the coding region 
 of the chemokine receptor-532 , ccr-532 , to be a significant risk factor for the 
 development of itbl . in moench 's study on 146 olt patients ccr-532 was a significant risk factor for itbl 
 ( incidence of itbl in ccr-532 patients was 30% versus 11.7% in ccr-5 
 wild - type patients ) and was correlated with a decreased survival rate after 
 olt . the different incidence of itbl of the study by 
 moench and this study may be a reason for the different findings , even though 
 both investigators used the same definition of itbl . donors were younger in 
 this study with 38.2  16 
 ( non - itbl patients ) and 42.9  17 ( itbl ) 
 versus 46  14 
 ( non - itbl ) and 52  14 ( itbl ) 
 in moench 's study . however , cold ischemic time was shorter in moench 's 
 investigation ( 564 minutes   ( itbl ) and 538   minutes ( non - itbl ) versus 637   minutes ( itbl ) and 
 558   minutes ( non - itbl ) ) . the use of arterial back table perfusion was also 
 routinely done for all organs that were harvested by a team of our own . analyzed ccr-532 polymorphism in 137 pediatric patients but 
 showed no correlation with biliary complications . the incidence of 
 itbl varies between 1.4% and 20% according to the literature , which might be a 
 problem of different definition of this disease [ 35 ] . the rate of itbl in our olt 
 patients ( 2100 patients between 1988 and 2004 ) is 4.0% . in the presented study 
 on 169 olt patients the overall incidence of itbl was 11.7% , but only due to a 
 selective inclusion of patients with the established diagnosis of itbl . this 
 practice of patient recruitment may be criticized , but we think it is justified 
 according to our low incidence of itbl . itbl rate in ccr-532 patients was virtually equal to the one in 
 ccr-5 wild - type patients . no statistically significant differences regarding 
 itbl or retransplantation were observed . why would 
 ccr-532 mutation promote the development of itbl ? ccr-532 is a 32-base - pair deletion within the 
 coding region of ccr-5 , which results in a frame shift and generates a 
 nonfunctional receptor . homozygous expression of ccr-532 is associated with a reduced risk of 
 asthma and with a reduced severity of rheumatoid arthritis [ 17 , 18 ] , 
 multiple sclerosis [ 19 , 20 ] , and primary biliary cirrhosis ( pbc ) . in other words , the nonfunctional nature of 
 ccr-532 protects the individual from autoimmune 
 diseases where ccr-5 seems to play a central pathophysiological role . these 
 data do not backup the theory , that immunological risk factors are dominant in 
 the development of itbl . likewise , a correlation of a reduced survival rate 
 with ccr-532 would not be consistent to the literature , 
 where ccr-532 mutation is associated with an increased 
 survival in renal , lung , heart   and islet 
 cell transplantation . in contrast 
 to those findings , ccr-532 is strongly associated with an increased 
 severity of psc . patients suffering from psc have been 
 described as carrying a higher risk for itbl , with a reported significantly 
 increased incidence of 15.8% to 25% [ 1 , 8 , 23 ] . another study reported psc as the only 
 independent risk factor for itbl with an incidence of 31% compared with 9%   of the 
 control group . however , 
 the problem of differentiation between itbl and recurrence of psc must be addressed . recurrence rates of 8.6% to 25% were described for psc after olt [ 2527 ] . the diagnose of recurrence 
 of psc is based on cholangiographic findings of intrahepatic , hilar and/or 
 exrahepatic strictures , duct irregularities and on the histopathological picture 
 of fibrous cholangitis and/or fibro - obliterative lesions with or without 
 ductopenia , biliary fibrosis , or biliary cirrhosis . most of these findings are neither 
 pathognomonic for either recurrence of psc nor itbl . all patients with itbl in this study 
 underwent percutaneous liver biopsy , and our pathologists ruled out psc 
 recurrence . since two 
 of three studies failed to show an association between itbl and ccr-532 gene polymorphism , a general recommendation 
 for screening of olt patients for ccr-532 does not seem to be justified .
it has been shown that certain chemokine receptor polymorphisms may correspond to certain complications after organ transplantation . 
 ischemic - type biliary lesion ( itbl ) encounters for major morbidity and mortality in liver transplant recipients . 
 so far , the exact cause for itbl remains unclear . 
 certain risk factors for the development of itbl like donor age and cold ischemic time 
                   are well described . in a previous study , a 32-nucleotide deletion of the chemokine receptor-532 ( ccr-532 ) 
 was strongly associated with the incidence of itbl in adult liver transplantation . 
 this study re - evaluates the association of ccr-532 gene polymorphism and the incidence of itbl . 
 169 patients were included into this retrospective 
                   analysis . 
 134 patients were homozygous for wild - type ccr-5 , 33 patients heterozygous , and 2 patients were homozygous for ccr-532 mutation . 
 there were no major differences in donor or recipients demographics . 
 no association was found between ccr-532 mutation and the development of itbl . 
 we conclude that ccr-532 is no risk factor for the development of itbl in our patient cohort .