ABCC2 and TDF Proximal Tubulopathy
• JID 2006:194 (1 December) • 1481
M A J O R A R T I C L E
Association between ABCC2 Gene Haplotypes
and Tenofovir-Induced Proximal Tubulopathy
Hassane Izzedine,1,aJean-Sebastien Hulot,2,aEric Villard,3Catherine Goyenvalle,2Stephanie Dominguez,4
Jade Ghosn,4Marc Antoine Valantin,4Philippe Lechat,2and Gilbert Deray1
1Department of Nephrology,
Curie–Paris IV, Paris, France
2Department of Pharmacology, Pharmacogenetics Unit,
4Department of Clinical Infectious Diseases, La Pitie ´-Salpe ˆtrie `re Hospital, Assistance Publique–Ho ˆpitaux de Paris, Universite ´ Pierre et Marie
3Centre d’Investigations Biome ´dicales, Pharmacogenetics Unit,
(See the editorial commentary by Hulgan and Haas, on pages 1471–4.)
Tenofovir disoproxil fumarate (TDF) may induce renal proximal tubulopathy (rPT). There are
no data on pharmacogenomic predictors of rPT in the genes encoding the multidrug-resistance protein (MRP) 2
and MRP4 transporters.
Mutational screening of the genes for MRP2 (ABCC2) and MRP4 (ABCC4) was performed using
genomic DNA from 13 human immunodeficiency virus type 1 (HIV-1)–infected patients (group 1) presenting
with TDF-induced rPT. Concomitantly, 17 unrelated HIV-1–infected patients who had received TDF therapy and
who did not have rPT (group 2) were included in a case-control analysis, to assess the influenceof single-nucleotide
polymorphisms (SNPs) identified in ABCC2 and ABCC4.
Six SNPs were identified in ABCC2. A significant allelic association between the 1249 GrA SNP and
TDF-induced rPT was observed (odds ratio, 6.11 [95% confidenceinterval,1.19–31.15];
were significantly associated with the onset of TDF-induced rPT—CATC appeared to be a predisposing haplotype,
as it was found in 40.9% of the group 1 case patients and in 13.7% of the group 2 control subjects (
whereas CGAC appeared to be a protective haplotype, as it was not observed in the group 1 case patients but was
present in 20.2% of the group 2 control subjects (P ! .01
morphism and TDF-induced rPT in the present study.
ABCC2 haplotypes are associated with rPT induced by TDF in HIV-1–infected patients.
).ABCC2haplotypesP ! .02
),P ! .01
). No association was observed between ABCC4 poly-
ences) is an orally administered bioavailable ester pro-
drug of tenofovir, an acyclic nucleotide analogue with
activity against retroviruses, including HIV-1, HIV-2,
and hepatitis B virus (HBV). Recently, Gallant et al. 
demonstrated that, in HIV-infected patients who had
Received 30 March 2006; accepted 11 May 2006; electronically published 26
Potential conflicts of interest: none reported.
Financial support: Gilead Sciences (unrestricted grant-in-aid for scientific
aH.I. and J.-S.H. contributed equally to this work.
Reprints or correspondence: Dr. Hassane Izzedine, Dept. of Nephrology, La Pitie ´-
Salpe ˆtrie `re Hospital, 47-80 Blvd. de l’Ho ˆpital, Assistance Publique–Ho ˆpitaux de
Paris, Pierre et Marie Curie University, 75013 Paris, France (hassan.izzedine@
psl.aphp.fr); or, Dr. Jean-Sebastien Hulot, Dept.ofPharmacology,Pharmacogenetics
Unit, La Pitie ´-Salpe ˆtrie `re Hospital, 47-80 Blvd. de l’Ho ˆpital, Assistance Publique–
Ho ˆpitaux de Paris, Pierre et Marie Curie University, 75013 Paris, France (jean-
The Journal of Infectious Diseases
? 2006 by the Infectious Diseases Society of America. All rights reserved.
not previously received antiretroviral therapy, the com-
bination of TDF-emtricitabine and efavirenz may be
the best choice for an initial nucleoside-analogueback-
bone in the treatment of such patients.
It has recently been reported that, in randomized,
controlled clinical trials in patients infected with HIV,
TDF has a globally safe renal adverse-effect profile [1–
4]. However, several cases of TDF-induced nephro-
toxicity, such as renal proximal tubulopathy (rPT),
nephrogenic diabetes insipidus (NDI), and acute renal
failure (ARF), have also been reported [3, 5–18].
TDF is extensively and rapidlyexcretedintotheurine
by the kidneys through glomerular filtration and tu-
bular secretion . TDF uptake through the proximal
tubule basolateral membrane is mediated bythehuman
organic anion transporter 1 (hOAT1), and cellular ef-
flux into the urine at the apical membrane is mediated
by multidrug-resistance protein (MRP) 2 [20, 21] and
MRP4 . The mechanism underlying TDF nephro-
toxicity remains undetermined but could be linked to
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1482 • JID 2006:194 (1 December) • Izzedine et al.
Table 1. Case patient (group 1) and control subject (group 2) characteristics.
(n p 13)
(n p 17)P
Male sex, no (%)
Duration of HIV-1 infection, years
Potassium level, mmol/L
Bicarbonate level, mmol/L
Serum creatinine level, mmol/L
Phosphorus level, mmol/L
Uric acid level, mmol/L
Glycosuria level, mmol/L
Proteinuria level, g/L
HAART, no (%)
Data are median (range) values, unless otherwise indicated. HAART, highly active
an impaired active efflux from the renal proximal tubular cells
by the above-mentioned renal drug transporters.
Human MRP2 is a glycosylated protein consisting of 1545
aa residues with a molecular mass of ∼190 kDa [23, 24]. The
ABCC2 (ATP binding cassette C2) gene, which encodes MRP2,
is composed of 32 exons encoded by an ∼45-kb gene located
on chromosome band10q24.2 [25–27].MutationsintheABCC2
gene are responsible for the pathogenesis of Dubin-Johnson
syndrome (DJS), which is characterized byadefectinthebiliary
excretion of bilirubin glucuronides [26, 28–30]. Moreover, we
have previously demonstrated that, in humans, a loss-of-func-
tion mutation in ABCC2 is associated with a marked modifi-
cation in the pharmacokinetics and toxicity of methotrexate,
another MRP2 substrate . It is thus likelythatABCC2genetic
variants may be associated with alterations in its function and,
differences in the disposition of substrate drugs .
Human MRP4 is another ABC transporter that is involved
in the efflux of cyclic nucleotides and some nucleoside mono-
phosphate analogues, includingnucleoside-basedantiviraldrugs.
Overexpression and amplification of the ABCC4 gene, which
encodes MRP4, is found in cell lines resistant to nucleoside
analogues such as azidothymidine monophosphate and 9-(2-
phosphonylmethoxyethyl)adenine (PMEA) . High levels of
MRP4 severely impair the antiviralefficacyofseveralnucleoside
analogues . Moreover, MRP4 has also been implicated in
the MgATP-activated transport of cAMP and cyclic guanosine
monophosphate [34, 35], a feature that suggests their involve-
ment in the regulation of intracellular cyclic nucleotide levels
. The influence of genetic variants of the ABCC4 gene has
not been previously investigated.
The localization of MRP2 and MRP4 (and also P-glycopro-
tein, encoded by the gene ABCB1) in the brush-border
membrane of renal proximal tubules indicatesthepotentialrole
these transporters play in the excretion of TDF from renal ep-
ithelial cells into the urine acrossthe apicalmembrane.Wethere-
fore postulated that genetic variants in ABCC2, ABCC4, or
ABCB1 might be associated with the risk of tubular toxicity
observed in patients treated with TDF. To investigate this, we
performed molecular screening for the coding sequencesinthese
genes in a study population of HIV-1–infected patients (almost
all of whom were white) with or without TDF-induced rPT.
PATIENTS, MATERIALS, AND METHODS
white persons and 1 of African descent) without HBV or hep-
atitis C virus coinfection and hepatic disease were included in
the present study. The study population was recruited from La
Pitie ´-Salpe ˆtrie `re, Saint Antoine, and Cochin Hospitals, which
are affiliated with Paris V and Paris VI Universities. The 24-
month study period extended between September 2003 and
A total of 30 unrelated HIV-1–infected subjects (29
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ABCC2 and TDF Proximal Tubulopathy • JID 2006:194 (1 December) • 1491
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