[Roles of UGT 1A1 gene mutation in the development of neonatal hyperbilirubinemia in Guangxi].

OBJECTIVE: Neonatal unconjugated hyperbilirubinemia is one of the most common conditions encountered by the practicing pediatricians. Although it is usually self-limited and benign, the condition is of importance because of the rare instances in which severe hyperbilirubinemia can lead to bilirubin encephalopathy or kernicterus. The uridine diphosphate-glucuronosyl transferase 1A1 (UGT 1A1) gene controls bilirubin conjugation by determining the structure of the enzyme glucuronosyltransferase, which is synthesized in the hepatocyte. In the recent years much has been learned about the relationship between UGT 1A1 gene mutation and neonatal hyperbilirubinemia. This study aimed to investigate the roles of UGT 1A1 gene mutation in the development of neonatal hyperbilirubinemia in Guangxi. METHODS: A total of 73 cases with hyperbilirubinemia and 31 healthy neonates were enrolled. UGT 1A1 G71R genotypes were identified by the (amplification refractory mutation system, ARMS) and direct sequencing method in all the neonates. To analyze the incidence of bilirubin encephalopathy, the peak (total serum bilirubin, TSB) concentration after 72 hours of age, and the possibility of TSB > 20 mg/dl of each group. RESULTS: (1) The frequencies of allele G71R were 0.1915 in this study, 0.2329 in hyperbilirubinemia group vs. 0.097 in healthy groups. The allele gene frequency of G71R in neonatal hyperbilirubinemia was higher than that in the normal group (P < 0.05). (2) Homozygous neonates had higher possibility to develop bilirubin encephalopathy and higher TSB concentration 72 hours after birth (28.57%, 23.12 ± 4.58) than the normal group (0%, 17.68 ± 2.69). The difference between the former two was significant (P < 0.001). (3) The TSB of the 5 neonates was > 20 mg/dl in G71R homozygous type, the odds ratio and 95%CI were 7.955 (1.349, 46.899). CONCLUSION: (1) G71R mutation gene was associated with neonatal jaundice in Guangxi region. (2) The possibility of TSB > 20 mg/dl in G71R homozygous was higher than those of the wild-type. (3) The incidence of bilirubin encephalopathy and TSB concentration after 72 hours of age for neonates who were homozygous to G71R gene were higher than the wild-type.

[Relationship between glucose-6-phosphate dehydrogenase gene mutations and neonatal jaundice in Naning, Guangxi].

OBJECTIVE: To study the correlation between glucose-6-phosphate dehydrogenase (G-6-PD) activities and three common mutations of G-6-PD gene G1388A, G1376T and A95G and investigate the effects of G-6-PD gene mutations on neonatal jaundice in Nanning, Guangxi. METHODS: One hundred and twenty-four neonates from Nanning, Guangxi, with hyperbilirubinemia were enrolled. The ARMS-PCR and PCR/REA methods were used to determine G-6-PD gene mutations. G-6-PD activities were measured using the NBT method. The incidence of acute bilirubin encephalopathy and the peak bilirubin concentration 72 hrs after birth were compared between the neonates with different genotypes and between the G-6-PD mutation and normal groups. The risk of blood serum bilirubin >340 mumol/L was evaluated by logistic regression analysis. RESULTS: Of the 124 cases, gene mutations were found in 37 cases, including G1388A (n=20), G1376T (n=14), A95G (n=4) and G1388A+A95G (n=1). Five cases (25%) showed normal G-6-PD activities in the G1388A gene mutation group and 4 (29%) had normal G-6-PD activities in the G1376T G1388A gene mutation group. All of 4 cases of A95G G1388A gene mutation showed a deficiency of G-6-PD activities. There were no significant differences in the incidence of acute bilirubin encephalopathy and the peak bilirubin concentration 72 hrs after birth between the G1388A and G1376T G1388A gene mutation groups. The incidence of acute bilirubin encephalopathy, the peak bilirubin concentration 72 hrs after birth and the risk of serum bilirubin >340 micromol/L in the G-6-PD mutation group were not different from the normal group. CONCLUSIONS: G1388A, G1376T and A95G are common G-6-PD gene mutations in Nanning, Guangxi. The false negative results may be received when the NBT method is used for diagnosis of G-6-PD deficiency. There are similar effects on the incidence of acute bilirubin encephalopathy and the peak bilirubin concentration 72 hrs after birth between different gene mutation groups. G-6-PD gene mutations alone may not contribute to the development of acute bilirubin encephalopathy and the changes of peak bilirubin concentration 72 hrs after birth and the risk of serum bilirubin >340 micromol/L.