Cdgler-Najjar syndrome type Ⅰ （CN-I） is the most severe type of hereditary unconjugated hyperbilirubinemia. It is caused by homozygous or compound heterozygous mutations of the UDP-glycuronosyltransferase gene （UG...Cdgler-Najjar syndrome type Ⅰ （CN-I） is the most severe type of hereditary unconjugated hyperbilirubinemia. It is caused by homozygous or compound heterozygous mutations of the UDP-glycuronosyltransferase gene （UGT1A1） on chromosome 2q37. Two patients clinically diagnosed with CN-I were examined in this paper. We sequenced five exons and their flanking sequences, specifically the promoter region of UGT1A 1, of the two patients and their parents. Quantitative real-time polymerase chain reaction （qRT-PCR） was used to determine the UGT1A1 gene copy number of one patient. In patient A, two mutations, c.239_245delCTGTGCC （p.Pro80HisfsX6; had not been reported previously） and c.1156G〉T （p.Va1386Phe）, were identified. In patient B, we found that this patient had lost heterozygosity of the UGTIA1 gene by inheriting a deletion of one allele, and had a novel mutation c.1253delT （p.Met418ArgfsX5） in the other allele. In summary, we detected three UGTIA 1 mutations in two CN-I patients： c.239_ 245delCTGTGCC （p.Pro80HisfsX6）, c.1253delT （p.MeH18ArgfsX5）, and c.1156G〉T （p.Va1386Phe）. The former two mutations are pathogenic; however, the pathogenic mechanism of c.1156G〉T （p.Va1386Phe） is unknown.展开更多
AIM： To identify the variants in U rase 1 （UGT1A1） gene in Gilbert＇s syndrome （GS） and to estimate the association between homozygosity for TA insertion and GS in India, as well as the frequency of TA insertion ...AIM： To identify the variants in U rase 1 （UGT1A1） gene in Gilbert＇s syndrome （GS） and to estimate the association between homozygosity for TA insertion and GS in India, as well as the frequency of TA insertion and its impact among normal controls in India. METHODS： Ninety-five GS cases and 95 normal controls were selected. Liver function and other tests were done. The promoter and all 5 exons of UGT1A1 gene were resequenced. Functional assessment of a novel trinucleotide insertion was done by in silico analysis and by estimating UGT1A1 promoter activity carried out by ludferase reporter assay of appropriate constructs in Hep G2 cell line. RESULTS： Among the GS patients, 80% were homozygous for the TA insertion, which was several-fold higher than reports from other ethnic groups. The mean UCB level was elevated among individuals with only one copy of this insertion, which was not significantly different from those with two copies. Many new DNA variants in UGT1A1 gene were discovered, including a trinucleotide （CAT） insertion in the promoter found in a subset （10%） of GS patients, but not among normal controls. In-silico analysis showed marked changes in the DNA-folding of the promoter and functional analysis showed a 20-fold reduction in transcription efficiency of UGT1A1 gene resulting from this insertion, thereby significantly elevating the UCB level. CONCLUSION： The genetic epidemiology of GS is variable across ethnic interactions among UGT1A1 groups and the epistatic promoter variants modulate bilirubin glucuronidation.展开更多
文摘Cdgler-Najjar syndrome type Ⅰ （CN-I） is the most severe type of hereditary unconjugated hyperbilirubinemia. It is caused by homozygous or compound heterozygous mutations of the UDP-glycuronosyltransferase gene （UGT1A1） on chromosome 2q37. Two patients clinically diagnosed with CN-I were examined in this paper. We sequenced five exons and their flanking sequences, specifically the promoter region of UGT1A 1, of the two patients and their parents. Quantitative real-time polymerase chain reaction （qRT-PCR） was used to determine the UGT1A1 gene copy number of one patient. In patient A, two mutations, c.239_245delCTGTGCC （p.Pro80HisfsX6; had not been reported previously） and c.1156G〉T （p.Va1386Phe）, were identified. In patient B, we found that this patient had lost heterozygosity of the UGTIA1 gene by inheriting a deletion of one allele, and had a novel mutation c.1253delT （p.Met418ArgfsX5） in the other allele. In summary, we detected three UGTIA 1 mutations in two CN-I patients： c.239_ 245delCTGTGCC （p.Pro80HisfsX6）, c.1253delT （p.MeH18ArgfsX5）, and c.1156G〉T （p.Va1386Phe）. The former two mutations are pathogenic; however, the pathogenic mechanism of c.1156G〉T （p.Va1386Phe） is unknown.
基金Supported by grants from the Department of Biotechnology, Government of India (to PPM) and the Department of Science & Technology, Government of West Bengal (to AC)
文摘AIM： To identify the variants in U rase 1 （UGT1A1） gene in Gilbert＇s syndrome （GS） and to estimate the association between homozygosity for TA insertion and GS in India, as well as the frequency of TA insertion and its impact among normal controls in India. METHODS： Ninety-five GS cases and 95 normal controls were selected. Liver function and other tests were done. The promoter and all 5 exons of UGT1A1 gene were resequenced. Functional assessment of a novel trinucleotide insertion was done by in silico analysis and by estimating UGT1A1 promoter activity carried out by ludferase reporter assay of appropriate constructs in Hep G2 cell line. RESULTS： Among the GS patients, 80% were homozygous for the TA insertion, which was several-fold higher than reports from other ethnic groups. The mean UCB level was elevated among individuals with only one copy of this insertion, which was not significantly different from those with two copies. Many new DNA variants in UGT1A1 gene were discovered, including a trinucleotide （CAT） insertion in the promoter found in a subset （10%） of GS patients, but not among normal controls. In-silico analysis showed marked changes in the DNA-folding of the promoter and functional analysis showed a 20-fold reduction in transcription efficiency of UGT1A1 gene resulting from this insertion, thereby significantly elevating the UCB level. CONCLUSION： The genetic epidemiology of GS is variable across ethnic interactions among UGT1A1 groups and the epistatic promoter variants modulate bilirubin glucuronidation.
