What you carry at this position in your DNA and what research says about it.
Pregnancy Liver Health: 6/10 evidence, 17 publications.
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Sample genotype (not yours): C/C
Typical Pregnancy Liver Risk and Standard Drug Clearance
Standard transport of bile acids supports typical liver function during pregnancy. Standard clearance rates are expected for most medications, though irinotecan may carry a higher risk of side effects.
What this genotype means: Typical risk of pregnancy-related cholestasis; Standard clearance of tacrolimus and fluorouracil; Increased risk of irinotecan-induced diarrhea.
Sample genotype (not yours): C/T
Slightly Elevated Pregnancy Liver Risk and Altered Drug Clearance
A single copy of the T allele is linked to a slightly higher risk of pregnancy-related liver itching and slower clearance of certain medications.
What this genotype means: Roughly 1.6x higher risk of pregnancy-related cholestasis; Slower clearance of tacrolimus; Increased risk of nausea during certain chemotherapies.
Sample genotype (not yours): T/T
Elevated Pregnancy Liver Risk and Slower Drug Clearance
Two copies of the T allele are linked to a higher risk of pregnancy-related liver itching and significantly slower clearance of several medications.
What this genotype means: Roughly 4.4x higher risk of pregnancy-related cholestasis; Significantly slower clearance of tacrolimus; Increased risk of severe chemotherapy side effects.
Gene function and biological role
Gene Function: The ABCC2 gene encodes multidrug resistance-associated protein 2, an ATP-dependent transport protein [1]. This transporter is primarily located on the apical membranes of hepatocytes, renal proximal tubule cells, and enterocytes [1]. It plays a critical role in the excretion of organic anions, including conjugated bilirubin and bile salts, into the bile [1]. Additionally, this protein is responsible for pumping various drugs and xenobiotics out of cells, directly influencing drug clearance and tissue distribution [1] [2]. Variations in this gene can impair bile flow or alter how the body processes medications [2].
Variant Impact: The rs3740066 variant is a synonymous nucleotide change located in exon 28 of the ABCC2 gene, resulting in an isoleucine codon at position 1324 [3]. Although it does not alter the amino acid sequence of the transporter protein, this synonymous change can influence mRNA stability, translation kinetics, or splicing efficiency [3]. Research indicates that this genetic variation is associated with altered transport activity of the protein [3] [4]. Consequently, it affects the clearance of bile acids during pregnancy and the elimination of several therapeutic drugs [3] [4].
Key Insight: A single silent genetic change that does not alter protein structure can still significantly impact liver function during pregnancy and alter the clearance of multiple chemotherapy drugs.
Location: ABCC2. Chromosome 10 · 10q24.2 · 99.8 Mb
Estimated prevalence by population
Global 45.6%; European 40.2%; African 54.8%; East Asian 59.4%; South Asian 45.9%; Americas 43.1%; Ashkenazi 42.1%; Finnish 44.2%; Middle Eastern 45.1%; Amish 23.9%.
Estimated CC genotype frequency.
Global 43.5%; European 46.4%; African 38.5%; East Asian 35.3%; South Asian 43.7%; Americas 45.1%; Ashkenazi 45.6%; Finnish 44.5%; Middle Eastern 44.1%; Amish 50.0%.
Estimated CT genotype frequency.
Global 10.9%; European 13.4%; African 6.8%; East Asian 5.3%; South Asian 10.4%; Americas 11.8%; Ashkenazi 12.3%; Finnish 11.2%; Middle Eastern 10.8%; Amish 26.1%.
Estimated TT genotype frequency.
Showing effects for C/C genotype
Endocrine & Reproductive
Pregnancy & Birth Complications
Pregnancy Cholestasis. Evidence: 3/10. Source: PMID 17997497. Typical Risk.
Pharmacogenomics
Chemotherapy Response
Chemotherapy Toxicity. Evidence: 5/10. Source: PMID 29507678. Typical Risk.
Irinotecan Toxicity. Evidence: 5/10. Source: PMID 18221820. Increased Risk.
Immunosuppressant & Biologic Response
Tacrolimus Clearance. Evidence: 6/10. Source: PMID 28316087. Typical Clearance.
Showing effects for C/T genotype
Pregnancy Cholestasis. Evidence: 3/10. Source: PMID 17997497. ~1.6x Higher Risk.
Chemotherapy Toxicity. Evidence: 5/10. Source: PMID 29507678. Increased Risk.
Irinotecan Toxicity. Evidence: 5/10. Source: PMID 18221820. Typical Risk.
Tacrolimus Clearance. Evidence: 6/10. Source: PMID 28316087. Slower Clearance.
Showing effects for T/T genotype
Pregnancy Cholestasis. Evidence: 3/10. Source: PMID 17997497. ~4.4x Higher Risk.
Chemotherapy Toxicity. Evidence: 5/10. Source: PMID 29507678. High Risk.
Tacrolimus Clearance. Evidence: 6/10. Source: PMID 28316087. Slowest Clearance.
What this genotype means for the people who carry it
Sample genotype: CC (Homozygous)
Presence of two copies of the C allele is associated with typical levels of the transporter protein. This baseline transporter activity allows for the normal excretion of bile acids and bilirubin from liver cells [1]. During pregnancy, this standard function helps protect against the accumulation of bile acids, maintaining a typical risk profile for intrahepatic cholestasis of pregnancy [1]. Regarding medication processing, standard clearance is expected for drugs like tacrolimus and fluorouracil [2]. However, clinical studies have noted that this genotype is associated with an increased risk of severe diarrhea when treated with the chemotherapy drug irinotecan [3]. Overall, liver function and drug transport operate at the typical population baseline.
Typical risk of pregnancy-related cholestasis; Standard clearance of tacrolimus and fluorouracil; Increased risk of irinotecan-induced diarrhea.
Sample genotype: CT (Heterozygous)
Inheriting one copy of the T allele is associated with altered activity of the transporter protein, which can affect bile and drug clearance. Clinical studies indicate that heterozygous individuals have a roughly 1.6-fold increased risk of developing intrahepatic cholestasis of pregnancy, a condition characterized by intense itching and elevated liver enzymes [1]. This genetic variation also impacts how the body processes several common medications. Slower metabolism of the immunosuppressant tacrolimus has been observed, which may raise its blood levels [2]. Additionally, there is an increased risk of experiencing side effects, such as nausea, when undergoing chemotherapy regimens containing fluorouracil, cyclophosphamide, or doxorubicin [3].
Roughly 1.6x higher risk of pregnancy-related cholestasis; Slower clearance of tacrolimus; Increased risk of nausea during certain chemotherapies.
Sample genotype: TT (Homozygous)
Possessing two copies of the T allele significantly alters the function of the transporter, leading to reduced excretion of bile acids and certain drugs. Research shows that individuals with this genotype have an estimated 4.4-fold higher risk of developing intrahepatic cholestasis of pregnancy, which can cause severe itching and requires careful clinical management [1]. This genotype also has pronounced effects on drug pharmacokinetics. The metabolism of tacrolimus is significantly slower, so the drug builds up more readily, with a greater toxicity risk [2]. Furthermore, patients undergoing chemotherapy with fluorouracil, cyclophosphamide, or doxorubicin face a higher likelihood of severe side effects, including neurotoxicity, neutropenia, and intense nausea [3].
Roughly 4.4x higher risk of pregnancy-related cholestasis; Significantly slower clearance of tacrolimus; Increased risk of severe chemotherapy side effects.
Variants with shared genetic architecture
rs717620 · ABCC2 Gene · Chr 10 · Medication Response
rs8187710 · ABCC2 Gene · Chr 10 · Chemotherapy Heart Risk
rs2273697 · ABCC2 Gene · Chr 10 · Carbamazepine Side Effects
Content updated August 2026.
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