title: Distribution of HPV16 and 18 intratypic variants in normal cytology, intraepithelial lesions, and cervical cancer in a Mexican population.
abstract: OBJECTIVE
  Several intratype variants of HPV16 and 18 have been identified. These variants are associated with populations from different geographic regions, and show a differential distribution among the severity of the cervical lesion, most likely due to different pathogenic potential. The objective of this study was to investigate the variant distribution of HPV16 and 18 in a Mexican population and its association with the severity of the cervical lesion and the histological lineage of cervical cancer.
  
  
  METHODS
  HPV types 16 and 18 detection was performed in 412 samples of preinvasive and invasive specimens from patients attending a Primary Health-Care Center, an Early Cervical Lesion Clinic, or a Cancer Center. Distribution of HPV variants was correlated with the cytological findings and tumor cell types using contingency tables. Statistical difference was tested with the Fisher's Exact Test or its Fisher-Freeman-Halton extension for RXC tables. Alpha value was set at the P < 0.05.
  
  
  RESULTS
  Among the 277 women included in this study without cancer, 63.5% (176 cases) had a normal cytology; from the remaining 101 women, 53.5% were LSIL (54 cases), and 46.5% HSIL (47 cases). From a total of 135 invasive carcinomas, 78.5% were squamous (106 cases); 6.6% adenocarcinoma (9 cases); 9.6% adenosquamous (ADSC) (13 cases); and 5.1% were undifferentiated carcinoma (7 cases). HPV16 E and AA-a were evenly distributed among preinvasive and invasive lesions. However, the isolate AA-c was exclusively found in cervical cancer. HPV18 Var-1(E) was almost exclusively found in invasive lesions, while the HPV18 Var-2(Af) predominated in normal or preinvasive lesions. In invasive cancer, this variant was found only in squamous tumors.
  
  
  CONCLUSIONS
  The differential distribution of HPV16 and 18 variants in cervical lesions we found further supports experimental data on the different pathogenic potential of HPV16 and 18 variants for cervical cancer development.
authors.affiliation: Unit of Biomedical Research in Cancer, National Cancer Institute/Biomedical Research Institute, National Autonomous University of Mexico, SSA Av. San Fernando No. 22, Col. Sección 16, Tlalpan 14080, Mexico City, Mexico. lizano@servidor.unam.mx
authors.forename: Marcela
authors.initials: M
authors.lastname: Lizano
authors.forename: Erick
authors.initials: E
authors.lastname: De la Cruz-Hernández
authors.forename: Adela
authors.initials: A
authors.lastname: Carrillo-García
authors.forename: Alejandro
authors.initials: A
authors.lastname: García-Carrancá
authors.forename: Sergio
authors.initials: S
authors.lastname: Ponce de Leon-Rosales
authors.forename: Alfonso
authors.initials: A
authors.lastname: Dueñas-González
authors.forename: Dulce Maria
authors.initials: DM
authors.lastname: Hernández-Hernández
authors.forename: Alejandro
authors.initials: A
authors.lastname: Mohar
mesh_terms: D002584:Cervix Uteri / Q000821:virology; D005260:Female; D052162:Human papillomavirus 16 / Q000302:isolation & purification*; D052161:Human papillomavirus 18 / Q000302:isolation & purification*; D006801:Humans; D008800:Mexico / Q000453:epidemiology; D030361:Papillomavirus Infections / Q000453:epidemiology / Q000473:pathology / Q000821:virology*; D002583:Uterine Cervical Neoplasms / Q000453:epidemiology / Q000473:pathology / Q000821:virology*; D002578:Uterine Cervical Dysplasia / Q000473:pathology / Q000821:virology*