TY - JOUR
T1 - Repeat long QT syndrome genetic testing of phenotype-positive cases
T2 - Prevalence and etiology of detection misses
AU - Medlock, Morgan M.
AU - Tester, David J.
AU - Will, Melissa L.
AU - Bos, J. Martijn
AU - Ackerman, Michael J.
N1 - Funding Information:
This research was supported by the Mayo Clinic Windland Smith Rice Comprehensive Sudden Cardiac Death Program. Dr Ackerman is a consultant for Biotronik, Boston Scientific, Medtronic, St Jude Medical, and Transgenomic. Intellectual property derived from Dr Ackerman's research program resulted in license agreements in 2004 between Mayo Clinic Health Solutions (formerly Mayo Medical Ventures) and PGxHealth (formerly Genaissance Pharmaceuticals, now recently acquired by Transgenomic). The Mayo Foundation for Medical Education and Research receives royalties from Transgenomic for the intellectual property used in their FAMILION LQTS genetic test. Dr Ackerman had full access to all the data in the study and takes responsibility for the integrity of the data and the accuracy of the data analysis.
PY - 2012/12
Y1 - 2012/12
N2 - Background: Approximately 75% of long QT syndrome (LQTS) has been explained genetically through research-based and, more recently, commercial genetic testing. While novel LQTS-susceptibility genes or mutations in unexplored regions of known genes underlie the genetic mechanism for some of the 25% "genotype-negative" remnant, it is likely that some cases represent false-negative test results owing to mutation detection failures. Objective: To determine the prevalence and etiology of false negatives that occurred with research-based mutational analysis involving denaturing high-performance liquid chromatography (DHPLC) followed by DNA sequencing (DHPLC-SEQ) in our previously published cohort of unrelated patients referred for LQTS genetic testing. Methods: Forty-four LQTS cases (29 men, average age 23 ± 15 years, average corrected QT interval 516 ± 56 ms) deemed genotype negative following DHPLC-SEQ were selected for repeat genetic testing using direct DNA sequencing. Results: LQTS-causing mutations were identified in 7 of 44 (16%) phenotype-positive/previously genotype-negative subjects, including 4 mutations in KCNQ1 (S225L, G568R, R591H, and R594Q), 2 in KCNH2 (H70R and G925R), and 1 in SCN5A (V411M). None of these variants were seen in more than 2600 reference alleles. Analysis of the misses revealed (1) normal DHPLC detection profile in 2, (2) allelic dropout in 2, (3) failure to correctly optimize DHPLC conditions in 1, and (4) failure to detect abnormal DHPLC signal in 2. Conclusions: Repeat genetic testing using direct DNA sequencing may be warranted for LQTS phenotype-positive individuals who were pronounced genotype negative during the decade of research-based mutational analysis that involved intermediate mutation detection methods such as DHPLC.
AB - Background: Approximately 75% of long QT syndrome (LQTS) has been explained genetically through research-based and, more recently, commercial genetic testing. While novel LQTS-susceptibility genes or mutations in unexplored regions of known genes underlie the genetic mechanism for some of the 25% "genotype-negative" remnant, it is likely that some cases represent false-negative test results owing to mutation detection failures. Objective: To determine the prevalence and etiology of false negatives that occurred with research-based mutational analysis involving denaturing high-performance liquid chromatography (DHPLC) followed by DNA sequencing (DHPLC-SEQ) in our previously published cohort of unrelated patients referred for LQTS genetic testing. Methods: Forty-four LQTS cases (29 men, average age 23 ± 15 years, average corrected QT interval 516 ± 56 ms) deemed genotype negative following DHPLC-SEQ were selected for repeat genetic testing using direct DNA sequencing. Results: LQTS-causing mutations were identified in 7 of 44 (16%) phenotype-positive/previously genotype-negative subjects, including 4 mutations in KCNQ1 (S225L, G568R, R591H, and R594Q), 2 in KCNH2 (H70R and G925R), and 1 in SCN5A (V411M). None of these variants were seen in more than 2600 reference alleles. Analysis of the misses revealed (1) normal DHPLC detection profile in 2, (2) allelic dropout in 2, (3) failure to correctly optimize DHPLC conditions in 1, and (4) failure to detect abnormal DHPLC signal in 2. Conclusions: Repeat genetic testing using direct DNA sequencing may be warranted for LQTS phenotype-positive individuals who were pronounced genotype negative during the decade of research-based mutational analysis that involved intermediate mutation detection methods such as DHPLC.
KW - Genetic testing, Mutation
KW - Genetics
KW - Genotyping
KW - Long QT syndrome
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U2 - 10.1016/j.hrthm.2012.08.010
DO - 10.1016/j.hrthm.2012.08.010
M3 - Article
C2 - 22885918
AN - SCOPUS:84870432572
VL - 9
SP - 1977
EP - 1982
JO - Heart Rhythm
JF - Heart Rhythm
SN - 1547-5271
IS - 12
ER -