Vol 19, No 2 (2012)
Original articles
Published online: 2012-03-30
Molecular diagnostics of families with long-QT syndrome
Cardiol J 2012;19(2):159-167.
Abstract
The Department of Pediatric Cardiology, Medical University of Silesia in Katowice-Ligota,
studied 24 patients with clinically diagnosed (using ECG) long-QT syndrome (LQTS) in 18 cases.
Nine patients were diagnosed with LQT1 and nine with LQT2. The other six individuals were
healthy, with no symptoms characteristic for prolonged QT syndrome, but came from families
with confirmed disease occurrence. The study was conducted on members of four families. In
order to search for mutations (using mSSCP and sequencing), genomic DNA was obtained
from patients to determine the expression levels of the genes KCNQ1 and KCNH2 (HERG),
involved in the occurrence of clinical signs of disease. Total RNA was extracted from peripheral
blood. Consent to the use of blood samples of patients had been given by the Bioethics
Commission of the Medical University of Silesia.
mSSCP analysis and sequencing did not confirm the occurrence of mutations in KCNQ1 and HERG associated with the occurrence of LQTS. Analysis of gene expression profile of KCNQ1 and HERG confirmed the presence of disease in people with a known clinical diagnosis. Overexpression, as well as reduced expression, was observed for the examined genes. KCNQ1 was inhibited in two families, whereas HERG was reduced in one and overexpressed in the other. Gene expression profile analysis showed abnormal expressions of KCNQ1 and HERG in healthy subjects, which may be a sign of predisposition to develop the disease. The novelty of our study involved the use of total mRNA isolated from human peripheral blood, and the very limited evidence in the literature to date regarding the assessment of gene expression profile of HERG and KCNQ1 in relation to the presence of prolonged QT syndrome. (Cardiol J 2012; 19, 2: 159–167)
mSSCP analysis and sequencing did not confirm the occurrence of mutations in KCNQ1 and HERG associated with the occurrence of LQTS. Analysis of gene expression profile of KCNQ1 and HERG confirmed the presence of disease in people with a known clinical diagnosis. Overexpression, as well as reduced expression, was observed for the examined genes. KCNQ1 was inhibited in two families, whereas HERG was reduced in one and overexpressed in the other. Gene expression profile analysis showed abnormal expressions of KCNQ1 and HERG in healthy subjects, which may be a sign of predisposition to develop the disease. The novelty of our study involved the use of total mRNA isolated from human peripheral blood, and the very limited evidence in the literature to date regarding the assessment of gene expression profile of HERG and KCNQ1 in relation to the presence of prolonged QT syndrome. (Cardiol J 2012; 19, 2: 159–167)
Keywords: long-QT syndromemolecular diagnosticsQRT-PCR (real-time PCR)mSSCP analysissequence analysis