Measurement Errors in Polymerase Chain Reaction Are a Confounding Factor for a Correct Interpretation of 5-HTTLPR Polymorphism Effects on Lifelong Premature Ejaculation: A Critical Analysis of a Previously Published Meta-Analysis of Six Studies

Paddy K C Janssen,Berend Olivier,Aeilko H Zwinderman,Marcel D Waldinger,Stephen D Ginsberg

doi:10.1371/journal.pone.0088031

Abstract

ObjectiveTo analyze a recently published meta-analysis of six studies on 5-HTTLPR polymorphism and lifelong premature ejaculation (PE).MethodsCalculation of fraction observed and expected genotype frequencies and Hardy Weinberg equilibrium (HWE) of cases and controls. LL,SL and SS genotype frequencies of patients were subtracted from genotype frequencies of an ideal population (LL25%, SL50%, SS25%, p = 1 for HWE). Analysis of PCRs of six studies and re-analysis of the analysis and Odds ratios (ORs) reported in the recently published meta-analysis.ResultsThree studies deviated from HWE in patients and one study deviated from HWE in controls. In three studies in-HWE the mean deviation of genotype frequencies from a theoretical population not-deviating from HWE was small: LL(1.7%), SL(−2.3%), SS(0.6%). In three studies not-in-HWE the mean deviation of genotype frequencies was high: LL(−3.3%), SL(−18.5%) and SS(21.8%) with very low percentage SL genotype concurrent with very high percentage SS genotype. The most serious PCR deviations were reported in the three not-in-HWE studies. The three in-HWE studies had normal OR. In contrast, the three not-in-HWE studies had a low OR.ConclusionsIn three studies not-in-HWE and with very low OR, inadequate PCR analysis and/or inadequate interpretation of its gel electrophoresis resulted in very low SL and a resulting shift to very high SS genotype frequency outcome. Consequently, PCRs of these three studies are not reliable. Failure to note the inadequacy of PCR tests makes such PCRs a confounding factor in clinical interpretation of genetic studies. Currently, a meta-analysis can only be performed on three studies-in-HWE. However, based on the three studies-in-HWE with OR of about 1 there is not any indication that in men with lifelong PE the frequency of LL,SL and SS genotype deviates from the general male population and/or that the SL or SS genotype is in any way associated with lifelong PE.

Highlights

Lifelong premature ejaculation (PE) is defined as a male sexual dysfunction characterized by ejaculation that always or nearly always occurs prior to or within about 1 minute of vaginal penetration, the inability to delay ejaculation on all or most vaginal penetrations, and with negative personal consequences, such as distress, bother, frustration, and/or the avoidance of sexual intimacy [1]
We show that out of the six previously published articles on 5-HTTLPR polymorphism and premature ejaculation used for the meta-analysis, laboratory data show that three studies were not in Hardy Weinberg equilibrium (HWE) and that in those three studies the deviation of HWE is due to technical insufficiencies and/or measurement errors of the polymerase chain reaction (PCR)
By analysing the data of the six studies and comparing these data with the calculated genotype frequencies of a theoretical population not deviating from HWE, we have found that the SL and SS genotype frequencies were normally distributed in the three studies that were in-HWE [7,11,12]

Summary

Introduction

Lifelong premature ejaculation (PE) is defined as a male sexual dysfunction characterized by ejaculation that always or nearly always occurs prior to or within about 1 minute of vaginal penetration, the inability to delay ejaculation on all or most vaginal penetrations, and with negative personal consequences, such as distress, bother, frustration, and/or the avoidance of sexual intimacy [1]. In 1998, Waldinger et al postulated that lifelong PE in terms of an IELT of less than 1 minute is related to genetic factors and to diminished central 5-HT neurotransmission and/or dysfunctional 5-HT1A and 5-HT2C receptors [5]. Lifelong PE is not regarded as a hereditary genetic disorder, Waldinger et al [6] reported a familial occurrence of lifelong PE in first degree relatives of some male patients with lifelong PE. After the publication of the first study on the influence of 5-HTTLPR. 5-HTTLPR genotype frequencies in patients and controls as reported by the authors of six studies.

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