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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.

Background: Gilbert syndrome is caused by defects in the uridine diphosphate glucuronosyltransferase 1A1 (UGT1A1) gene. These mutations differ among different populations and many of them have been found to be genetic risk factors for the development of neonatal jaundice. Objectives: The objective was to determine the frequencies of the following mutations in the UGT1A1 gene: A(TA)₇TAA (the most common cause of Gilbert syndrome in Caucasians), G71R (more common in the Japanese and Taiwanese population), and G493R (described in a homozygous Malay woman with Crigler-Najjar syndrome type 2) in a group of Malaysian babies with hyperbilirubinemia and a group of normal controls. Methods: The GeneScan fragment analysis was used to detect the A(TA)₇TAA variant. Mutation screening of both G71R and G493R was performed using denaturing high performance liquid chromatography. Results: Fourteen out of fifty-five neonates with hyperbilirubinemia (25%) carried the A(TA)₇TAA mutation (10 heterozygous, 4 homozygous). Seven out of fifty controls (14%) carried this mutation (6 heterozygous, 1 homozygous). The allelic frequencies for hyperbilirubinemia and control patients were 16 and 8%, respectively (p = 0.20). Heterozygosity for the G71R mutation was almost equal among both groups (5.5% for hyperbilirubinemia patients and 6.0% for controls; p = 0.61). One subject (1.8%) in the hyperbilirubinemia group and none of the controls were heterozygous for the G493R mutation (p = 0.476). Conclusions: The A(TA)₇TAA seems more common than the G71R and G493R mutations in the Malaysian population.

Our results suggested that the methylation level was affected by the severity of the clinical symptoms of schizophrenia and might also be influenced by pharmacological treatment. The epigenetic alteration of COMT in the peripheral blood could be a potential peripheral biomarker of schizophrenia.

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