8个Gilbert综合征家系UGT1A1变异谱调查及分析

Investigation and analyses of UGT1A1 variant spectrum for 8 Gilbert syndrome families

目的研究中国人群Gilbert综合征与UGT1A1基因变异的关系。方法选取8个Gilbert综合征家系成员外周静脉血提取基因组DNA,采用聚合酶链反应（PCR）扩增UGT1A1基因上游的启动子TATA盒及第1-5外显子序列,PCR产物测序后行遗传变异分析;并对先症者进行1年以上的随访观察。结果在6个完整的核心家系中,先症者双亲的发病率仅为25%（〈50%）。4例先症者各有1名兄妹,其中1例先症者的同卵双胎也发病,而其余3例先症者只有1例的弟弟发病。1个家系第2代4名女性中只有1人发病。共检测到3个错义突变位点（c.211G〉A,p.G71R,rs4148323;c.686C〉A,p.P229Q,rs35350960;c.1091C〉T,p.P364L,rs34946978）和1个位于启动子区TATA盒的2个额外碱基TA插入变异（c.-40_-39ins TA,rs3064744）。所有15例患者中（包括8例先症者和7个家系成员）,12例携带UGT1A1的纯合变异或2个无连锁（1个来自父亲,1个来自母亲）的杂合变异（12/15）,3例患者仅携带单个UGT1A1基因的杂合变异;而携带单个杂合变异的14个家系成员中仅有1人表现为Gilbert综合征,其余13人胆红素水平均正常。结论 Gilbert综合征与UGT1A1的变异相关,并呈现出叠加效应,携带纯合变异或2个不连锁杂合（c.-40_-39ins TA/c.211G〉A;c.211G〉A/c.1091C〉T）变异者容易表现为Gilber综合征,而大多数携带单个杂合变异者则表现为正常。

Objective To determine the correlation of Gilbert syndrome（ GS） and UGT1A1 variations. Methods The genome DNA was extracted from the peripheral blood samples of 8 probands（ subjected in our outpatient department from August 2011 to March 2014） and their family members. The promoter and coding regions of UGT1A1 were amplified by polymerase chain reaction（ PCR）. The amplified DNA fragments was sequenced and then family pedigree analysis was analyzed. Bilirubin levels of all probands were followed up for at least 1 year. Results The incidence of GS was only 25%（ less than 50%） among the probands’ parents in the 6 complete nuclear families. The twin brother of a proband was also a GS patient.Only one brother of the proband was affected in other 3 families in which the probands had a brother or sister.Only a sister was detected with unconjugated hyperbilirubinemia in 4 sisters of the second generations. Three missense variants in coding regions（ c. 211 G 〉 A,p. G71 R in exon 1; c. 686 C 〉 A,p. P229 Q in exon 1; c.1091 C 〉 T,P364 L in exon 4） and 2 extra bases insertion variant in promoter（ c.- 40_- 39 ins TA） were identified. Twelve of 15 affected subjects carried homozygous or compound heterozygous variations which contained at least 2 unlinked variants（ 0. 80） and the other 3 carried single UGT1A1 heterozygous variations,while 13 of 14 family members carrying single heterozygous variations kept normal bilirubin levels. Conclusion GS is strongly associated with UGT1A1 variations in an additive effect. Those carrying homozygous or compound unlinked heterozygous UGT1A1 variations（ c.- 40_- 39 ins TA / c. 211 G 〉 A; c. 211 G 〉 A / c. 1091 C 〉 T） are more common suffering from GS,while those carrying single heterozygous variations are healthy.