Analysis of Human Imprinting gene 11p15.5
Date Issued
2008
Date
2008
Author(s)
Yang, Chin-Wen
Abstract
The imprinting regions at chromosome11p15.5 are associated with Beckwith-Wiedemann syndrome (BWS) and Russell-Silver syndrome (RSS). The most frequent findings are the defect of methylation on the imprinting loci LIT1 and H19, both located at chromosome11p15.5, in patients with BWS and RSS. Therefore this study is to develop a simplified and high-performance method for assessment of the degrees of DNA methylation. The novel method is designed by coupling the methylation-sensitive endonuclease treatment and the quantitative polymerase chain reaction (called E-Q-PCR). And the method was employed to evaluate the variable of methylation on the imprinting loci LIT1 and H19. A total of 10 BWS patients, 20 RSS patients and 20 healthy individuals were analysed. The methylation index (MI) of the 20 health individuals was estimated to be ranged from 39.29 %~68.51 % (mean ± 2 SD = 53.9% ± 14.61) which was arbitrarily designated as the normal range of the MI. For the ten BWS patients, five reveal LIT1 hypomethylation with the MI values, 8.42 %, 8.47 %, 7.35 %, 19.04 % and 4.48 % (mean ± 2 SD = 9.59 % ± 11.08 ), four show normal LIT1 methylation pattern, MI= 55.28 %, 51.34 %, 55.89 % and 57.8 %, (mean ± 2 SD = 55.08 % ± 5.42), and one has the MI value (MI= 36.7 %) between the normal and hypomethylation ranges, possibly caused by a genetic mosaicism. For the 20 RSS patients, neither hypomethylation nor hypermethylation was identified. I noted unexpected results were obtained when E-Q-PCR was performed on the H19 locus which might be due to the secondary structure of the single strand DNA produced during PCR. Despite this, E-Q-PCR remains to be a practical method for estimating degrees of DNA methylation since it has been successfully applied on the LIT1 locus. This molecular approach deserves more effort to further characterize its sensitivity, specificity, and cost-effective analyses when compared with other molecular diagnostic techniques.
Subjects
imprinting
methylation
methylation-sensitive endonuclease-coupled quantitative polymerase chain reaction (E-Q-PCR)
Beckwith-Wiedemann syndrome
Russell-Silver syndrome
SDGs
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