ABCMdb

ABCB4 p.Arg549His

Predicted by SNAP2:	A: D (59%), C: D (53%), D: D (80%), E: D (75%), F: D (75%), G: D (66%), H: D (59%), I: D (66%), K: N (93%), L: D (71%), M: D (59%), N: N (53%), P: D (75%), Q: N (61%), S: N (72%), T: N (61%), V: D (66%), W: D (80%), Y: D (71%),
Predicted by PROVEAN:	A: D, C: D, D: D, E: D, F: D, G: D, H: D, I: D, K: N, L: D, M: D, N: D, P: D, Q: D, S: D, T: D, V: D, W: D, Y: D,

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[hide] Hepatobiliary phospholipid transporter ABCB4, MDR3... Dig Liver Dis. 2008 May;40(5):366-70. Epub 2007 Dec 20. Floreani A, Carderi I, Paternoster D, Soardo G, Azzaroli F, Esposito W, Montagnani M, Marchesoni D, Variola A, Rosa Rizzotto E, Braghin C, Mazzella G
Hepatobiliary phospholipid transporter ABCB4, MDR3 gene variants in a large cohort of Italian women with intrahepatic cholestasis of pregnancy.
Dig Liver Dis. 2008 May;40(5):366-70. Epub 2007 Dec 20., [PMID:18083082]

Abstract [show]
BACKGROUND: Intrahepatic cholestasis of pregnancy is a multifactorial disorder of pregnancy associated with a genetic background. AIM: To evaluate the genetic contribution of ABCB4, MDR3 gene in the development of intrahepatic cholestasis of pregnancy in a large cohort of Italian subjects. METHODS: This study represents an extension of a previous multicentre-prospective study including three Italian referral centres. In all, we enrolled 96 women at the 3rd trimester of pregnancy. Genomic DNA was extracted from peripheral venous blood leucocytes by standard procedures. Polymerase chain reaction was used to amplify exon 14, 15 and 16 of MDR3 gene. RESULTS: We found 3 non-synonymous heterozygous mutations in exon 14 (E528D, R549H, G536A), 1 in exon 15 (R590Q) and 2 in exon 16 (R652G, T6671). MDR3 gene variants in exons 14, 15 and 16 occurred in 7/96 of pregnant mothers with intrahepatic cholestasis of pregnancy (7.2%), and in none of 96 pregnant controls matched for age and parity. All seven patients had normal gamma-glutamyl transpeptidase, normal bilirubin, but high levels of both alanine transferase and serum bile acids. One had cholesterol biliary lithiasis. The outcome of pregnancy was normal in four cases (with vaginal delivery), while there was one fetal distress. CONCLUSIONS: MDR3 mutations are responsible for the development of intrahepatic cholestasis of pregnancy in only a small percentage of Italian women. Further genetic studies are warranted, however, to clarify the role of different mutations in intrahepatic cholestasis of pregnancy.

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No. Sentence Comment
10 We found 3 non-synonymous heterozygous mutations in exon 14 (E528D, R549H, G536A), 1 in exon 15 (R590Q) and 2 in exon 16 (R652G, T6671). Login to comment
80 There is a difference, however, in the phenotypic expression of this condition by comparison Table 4 Clinical details of ICP patients with MDRR3 mutations Patient #1 E528D Patient #2 R549H Patient #3 G536R Patient #4 R590Q Patient #5 R652G Patient #6 T667I Patient #7 R652G Onset of pruritus 3rd trimester 3rd trimester 3rd trimester 3rd trimester 3rd trimester 3rd trimester 3rd trimester Parity 0002 0001 0001 0001 0001 0001 0001 Previous ICP No Yes Yes No No No No Peak of AST (U/L) 163 88 129 62 789 119 60 Peak of ALT (U/L) 98 121 137 88 1186 125 78 Bilirubin (mg/dL) 0.60 0.61 0.89 1.2 0.57 0.3 0.78 Peak of GGT (U/L) 8 15 19 10 25 35 5 Cholesterol lithiasis No No Yes No No No No Total bile salts (␮M/L) 3.3 6.3 10.1 60 76.3 25.3 4.0 Delivery Vaginal Vaginal Caesarean Vaginal Caesarean Caesarean Vaginal ICP, intrahepatic cholestasis of pregnancy; AST, aspartate aminotransferase; ALT, alanine aminotransferase. Login to comment
81 There is a difference, however, in the phenotypic expression of this condition by comparison Table 4 Clinical details of ICP patients with MDRR3 mutations Patient #1 E528D Patient #2 R549H Patient #3 G536R Patient #4 R590Q Patient #5 R652G Patient #6 T667I Patient #7 R652G Onset of pruritus 3rd trimester 3rd trimester 3rd trimester 3rd trimester 3rd trimester 3rd trimester 3rd trimester Parity 0002 0001 0001 0001 0001 0001 0001 Previous ICP No Yes Yes No No No No Peak of AST (U/L) 163 88 129 62 789 119 60 Peak of ALT (U/L) 98 121 137 88 1186 125 78 Bilirubin (mg/dL) 0.60 0.61 0.89 1.2 0.57 0.3 0.78 Peak of GGT (U/L) 8 15 19 10 25 35 5 Cholesterol lithiasis No No Yes No No No No Total bile salts (òe;M/L) 3.3 6.3 10.1 60 76.3 25.3 4.0 Delivery Vaginal Vaginal Caesarean Vaginal Caesarean Caesarean Vaginal ICP, intrahepatic cholestasis of pregnancy; AST, aspartate aminotransferase; ALT, alanine aminotransferase. Login to comment

[hide] Intrahepatic cholestasis of pregnancy: three novel... Aliment Pharmacol Ther. 2006 Jun 1;23(11):1649-53. Floreani A, Carderi I, Paternoster D, Soardo G, Azzaroli F, Esposito W, Variola A, Tommasi AM, Marchesoni D, Braghin C, Mazzella G
Intrahepatic cholestasis of pregnancy: three novel MDR3 gene mutations.
Aliment Pharmacol Ther. 2006 Jun 1;23(11):1649-53., [PMID:16696816]

Abstract [show]
BACKGROUND: The aetiology of intrahepatic cholestasis of pregnancy is unknown, but more than 10 different MDR3 gene mutations have recently been identified. AIM: To evaluate the genetic contribution of the MDR3 gene in the pathogenesis of intrahepatic cholestasis of pregnancy in Italian subjects. METHODS: We performed a multicentre prospective case-control study, enrolling 80 women with intrahepatic cholestasis of pregnancy at the third trimester of pregnancy and 80 pregnant women without intrahepatic cholestasis of pregnancy. Genomic DNA was extracted from peripheral venous blood leucocytes using standard procedures. The polymerase chain reaction was used to amplify exon 14 of the MDR3 gene and the polymerase chain reaction products were sequenced using a Big Dye Terminator Cycle Sequencing kit. RESULTS: Three novel non-synonymous heterozygous mutations in exon 14 were found (4%; E528D, R549H, G536R) among the 80 intrahepatic cholestasis of pregnancy patients, whereas the pregnant controls were all negative for exon 14 polymorphisms. The three patients involved had normal GGT and bilirubin, but high levels of both ALT and serum bile acids. One had cholesterol bile stones. The outcome of pregnancy was normal for two (with vaginal delivery), while foetal distress was recorded in the third. CONCLUSIONS: These three novel mutations add further information on the involvement of the MDR3 gene in intrahepatic cholestasis of pregnancy. As in other studies, we found only heterozygous mutations that could cause an impaired transport protein function, not its absence (which is responsible for more severe liver disease). Different genetic backgrounds might justify the presence of novel MDR3 gene mutations.

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No. Sentence Comment
6 Results Three novel non-synonymous heterozygous mutations in exon 14 were found (4%; E528D, R549H, G536R) among the 80 intrahepatic cholestasis of pregnancy patients, whereas the pregnant controls were all negative for exon 14 polymorphisms. Login to comment
70 The R549H mutation is located between the linker region and the Walker B domain. Login to comment
72 Patient #1 E528D mutation Patient #3 G536R mutation Patient #2 R549H mutation Figure 1. Login to comment
75 Clinical details of ICP patients with heterozygous mutations Patient #1 E528D Patient #2 R549H Patient #3 G536R Onset of pruritus 3rd trimester 3rd trimester 3rd trimester Parity 0002 0001 0001 Previous ICP No Yes Yes Peak of AST (U/L) 163 88 129 Peak of ALT (U/L) 98 121 137 Bilirubin (mg/dL) 0.60 0.61 0.89 Peak of GGT (U/L) 8 15 19 Cholesterol lithiasis No Yes No Total bile salts (lM/L) 3.3 6.3 10.1 Delivery Vaginal Vaginal Caesarean ICP, intrahepatic cholestasis of pregnancy; AST, aspartate aminotransferase; ALT, alanine aminotransferase. A drawback of our study lies is not having sequenced the whole MDR3 gene, as our study design only involved sequencing exon 14; may also consequently underestimate the real prevalence of MDR3 mutations in ICP patients. Login to comment