A polymorphic mutation, c.-3279T>G, in the UGT1A1 promoter is a risk factor for neonatal jaundice in the Malay population.

The uridine diphosphoglucuronate-glucuronosyltransferase 1A1 (UGT1A1) gene encodes the enzyme responsible for bilirubin glucuronidation. To evaluate the contribution of UGT1A1 promoter mutations to neonatal jaundice, we determined the genotypes of c.-3279T>G, c.-3156G>A, and A(TA)7TAA in Malay infants with neonatal jaundice (patients) and in infants without neonatal jaundice (controls). In our population study, only c.-3279T>G was associated with neonatal jaundice. The genotype distributions between both groups were significantly different (p = 0.003): the frequency of homozygosity for c.-3279G was much higher in patients than those in controls. Allele frequency of c.-3279G was significantly higher in patients than those in controls (p = 0.006). We then investigated changes in transcriptional activity because of c.-3279T>G. Luciferase reporter assay in HepG2 cells demonstrated that transcriptional activity of the c.-3279G allele was significantly lower than that of the c.-3279T allele in both the absence and presence of bilirubin. Luciferase reporter assay in COS-7 cells elucidated that c.-3279T>G modified the synergistic effects of the nuclear factors associated with transcriptional machinery. In conclusion, the c.-3279T>G mutation in the UGT1A1 promoter is a genetic risk factor for neonatal jaundice.

Germ-line mutation of KCNQ2, p.R213W, in a Japanese family with benign familial neonatal convulsion.

BACKGROUND: Benign familial neonatal convulsion (BFNC) is an autosomal-dominantly inherited epilepsy of neonates. The KCNQ2 and KCNQ3 genes have been cloned as the responsible genes for BFNC. Detection of mutations in these genes is helpful for confirmation of BFNC or differential diagnosis of convulsive disorders in the neonatal period. METHODS: A Japanese family with BFNC was investigated. Two siblings were clinically diagnosed as having BFNC. KCNQ2 and KCNQ3 were screened for mutations using a combination of polymerase chain reaction and denaturing high-performance liquid chromatography. Nucleotide substitutions were confirmed by direct sequencing. RESULTS: In the affected siblings a C-to-T heterozygous substitution was detected at nucleotide 683 (c.683C>T) in KCNQ2, leading to substitution of arginine with tryptophan at amino acid position 213 (p.R213W) in the S4 voltage-sensing domain of the KCNQ2 protein. The detected mutation may disrupt this highly conserved region among potassium channel proteins. The c.683C>T substitution in KCNQ2 was not present in the parents. KCNQ3 was also analyzed and a single nucleotide polymorphism, c.1241A>G (National Center for Biotechnology Information (NCBI), SNP ID: rs2303995), was detected in the index family. CONCLUSIONS: Two siblings with BFNC had a novel heterozygous missense mutation, p.R213W, in KCNQ2. This mutation may affect potassium gating, leading to neuronal excitability or convulsions in the patients. Furthermore, neither of the parents had the p.R213W mutation, indicating that it was a germ-line mutation. The possibility of recurrence of such a germ-line mutation in the next siblings should be explained during genetic counseling.

Screening for G71R mutation of the UGT1A1 gene in the Javanese-Indonesian and Malay-Malaysian populations.

BACKGROUND: There are significant differences in the prevalence and severity of neonatal jaundice among various populations. Recently, it has been reported that a mutation of the UGT1A1 gene, glycine to arginine at codon 71 (G71R), is related to the development of neonatal jaundice in East Asian populations. However, whether the G71R mutation contributes to the high incidence of neonatal jaundice in different Asian populations remains unknown. The authors screened for this mutation in the Javanese-Indonesian and Malay-Malaysian populations. METHODS: One hundred and thirty-six subjects were enrolled in this study: 68 Javanese-Indonesian adults and 68 Malay-Malaysian newborns (32 with jaundice and 36 without jaundice). Denaturing high-performance liquid chromatography (DHPLC) was used to screen for the G71R mutation, and the results were confirmed by nucleotide sequencing analysis. RESULTS: With DHPLC, the authors easily and clearly detected seven subjects carrying the G71R mutation: two Javanese-Indonesian adults and five Malay-Malaysian newborns. In the 68 Javanese-Indonesian adults, the genotype distribution for G71R mutation was 66 G/G, two G/R and no R/R genotypes, and the mutated allele frequency was 0.015. In the 68 Malay-Malaysian newborns, genotype distribution for the mutation was 63 G/G, five G/R and no R/R genotypes, and the mutated allele frequency was 0.037. The genotype distributions did not differ significantly between the newborns with jaundice and those without jaundice. CONCLUSION: The G71R mutation is present, but very rare, in Javanese-Indonesians and Malay-Malaysians. Thus, G71R mutation may not contribute to the high incidence of the neonatal jaundice in South-east Asian populations. DHPLC analysis is a very useful method for detecting the G71R mutation.