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HPV Genotypes

Human Papillomavirus (HPV) Genotypes and their risk classifications

 

Human papillomavirus (HPV) genotyping is a molecular test used to identify the specific genetic variant (type) of HPV present in a person’s sample (e.g., cervical swab). HPV consists of more than 200 related viruses, around 40 of which infect the anogenital region. These anogenital HPVs can be broadly classified into low-risk and high-risk types, based on their potential to cause cancer. Low-risk types (such as HPV 6 and 11) are more commonly linked to benign conditions like genital warts, whereas high-risk types are associated with precancerous lesions and various cancers—most notably cervical cancer, but also anal, penile, vulvar, vaginal, and oropharyngeal cancers.

 

High-Risk HPV Genotypes

Definition
High-risk HPV (hrHPV) genotypes are strains that, when infections persist, can lead to the development of precancerous lesions and cancers, most notably cervical cancer, but also anal, penile, vulvar, vaginal, and oropharyngeal cancers. Persistent infection with high-risk HPV can cause changes in the cells of the cervix (dysplasia), which may progress to cancer over time if not detected and treated.

Examples

  • HPV 16: The most oncogenic (cancer-causing) type. Accounts for approximately 50% of cervical cancers worldwide and is strongly associated with other HPV-related cancers.
  • HPV 18: The second most common type found in cervical cancer. Together with HPV 16, these two are responsible for the majority of cervical cancers.
  • Other high-risk genotypes: HPV 31, 33, 35, 39, 45, 51, 52, 56, 58, 59, 66, and 68. These types collectively contribute to a significant fraction of high-grade cervical intraepithelial neoplasias (CIN2/3) and cervical cancers, even though each is individually less common than HPV 16 and 18.

Clinical Significance

  • Screening: Detection of high-risk HPV is critical in cervical cancer screening programs (e.g., Pap test + HPV co-testing or HPV primary screening).
  • Disease Progression: Persistent infection with high-risk types can lead to cellular changes that may progress from mild dysplasia to severe dysplasia and, eventually, invasive cancer.
  • Prevention: Vaccines currently target the most common high-risk types (especially HPV 16 and 18, and in some vaccines additional genotypes like 31, 33, 45, 52, and 58), offering protection against the majority of HPV-related cancers.

 

Low-Risk HPV Genotypes

Definition
Low-risk HPV genotypes typically do not lead to cancer. While they may cause benign (non-cancerous) lesions, such as genital warts and low-grade cervical cell changes, these infections rarely progress to cancer.

Examples

  • HPV 6 and 11: The most common low-risk types, responsible for the majority of genital warts (condylomas) and low-grade cervical changes.

Clinical Significance

  • Genital Warts: Infections with low-risk types like HPV 6 and 11 are the primary cause of visible genital warts.
  • Low-Grade Cervical Changes: Though they can cause mild dysplasia, these changes often regress spontaneously and are less likely to progress to high-grade lesions or cancer.
  • Treatment: While low-risk HPV types are not likely to become cancerous, treatment for associated warts or dysplastic lesions may be necessary for patient comfort and to prevent further spread.

Summary

  • High-risk HPV genotypes (e.g., HPV 16, 18, 31, 33, 45, 52, 58, etc.) are associated with a significant risk of precancerous lesions and progression to cancers of the cervix, anus, and other sites.
  • Low-risk HPV genotypes (e.g., HPV 6, 11) more often lead to benign conditions such as genital warts or mild cervical dysplasia, which typically do not progress to cancer.

Ongoing research and vaccination efforts focus on preventing infection with the high-risk genotypes, thereby greatly reducing the incidence of HPV-related cancers worldwide.

 

Disclaimer

This information is provided for educational purposes and should not replace professional medical advice. For personalized guidance on HPV risk, diagnosis, vaccination, or treatment, consult a qualified healthcare provider.

https://www.who.int/teams/health-product-policy-and-standards/standards-and-specifications/norms-and-standards/vaccine-standardization/human-papillomavirus