Screening of a novel hepatic syndrome and its uses
The invention concerns methods of screening for a hepatic syndrome occurring in the young adult and associating cholesterol biliary microlithiasis, intrahepatic cholestasis and several mutations of the MDR3 gene. The invention is also directed to methods for the treatment of said syndrome. The hepatic syndrome screening methods comprise detecting, from a nucleic acid sample extracted from peripheral blood mononucleate cells, heterozygous mutations of the MDR3 gene and/or homozygous mutations of the MDR3 gene that do not eliminate the expression of the protein expressed by the MDR3 gene, which has phosphatidylcholine carrier activity, in adult subjects associating cholesterol biliary microlithiasis and intrahepatic cholestasis.
1. A method of screening for a hepatic syndrome in a human subject with symptomatic cholelithiasis, wherein said hepatic syndrome is characterized by (i) cholesterol microcholelithiasis, (ii) intrahepatic cholestasis and (iii) one or more mutations of the MDR3 gene, wherein said method comprises:
obtaining a sample of nucleic acids extracted from peripheral blood mononuclear cells of said human subject,
detecting in said sample of nucleic acids the presence of a A523G mutation in exon 6 of the MDR3 gene, leading to the amino acid mutation T175A; and
determining whether that human subject has said hepatic syndrome, the presence of said mutation in said nucleic acid sample being indicative of the susceptibility to said hepatic syndrome.
2. The method of claim 1 , further comprising detecting in said sample the presence of another mutation of the MDR3 gene wherein said mutation is selected from the group consisting of i) the C959T mutation in exon 9, leading to amino acid S320F and ii) the 1327InsA insertion in exon 12.
3. The method of claim 1 , wherein said human subject is a young adult.
4. The method according to claim 1 , wherein said detecting step comprises:
a) amplifying said sample of nucleic acids with a pair of primers of SEQ ID NO:9 and SEQ ID NO: 10 to produce an amplified sequence; and
b) detecting in said amplified sequence, the presence of said A523G mutation in exon 6 of the MDR3 gene.
5. The method of claim 1 , wherein said detecting step comprises:
a) a first amplification of said sample of nucleic acids with pairs of primers selected from the group consisting of the pair of primers of SEQ ID NO:9 and SEQ ID NO: 10, and the pair of primers of SEQ ID NO:7 and SEQ ID NO:8;
b) a second amplification of the product of said first amplification using the pair of primers of SEQ ID NO: 1 and SEQ ID NO:2 for amplifying a 321 bp fragment covering exon 6; and
c) detecting the presence of said mutation in the amplified product of step b).
6. The method of claim 1 , wherein said method comprises:
a) a first amplification with a first pair of primers of SEQ ID NO:7 and SEQ ID NO:8; and
b) a second amplification of the product obtained in a) consisting of amplification with a second pair of primers of SEQ ID NO:9 and SEQ ID NO:10.
7. The method of claim 2 , wherein said method comprises:
a) a first amplification with a first pair of primers of SEQ ID NO: 7 and SEQ ID NO: 8; and
b) a second amplification of the product obtained in a) consisting of amplification with a second pair of primers of SEQ ID NO: 3 and SEQ ID NO: 4.
8. The method of claim 2 , wherein said method comprises:
a) a first amplification with a first pair of primers of SEQ ID NO: 7 and SEQ ID NO: 8; and
b) a second amplification of the product obtained in a) consisting of amplification with a second pair of primers of SEQ ID NO: 5 and SEQ ID NO: 6.