An Expert Explains the Different Hepatitis C Genotypes

There are many types of hepatitis -- hepatitis A, B and C are three of the most common -- but did you know that there are also many types of hepatitis C? Depending on one's hepatitis C genotype, a doctor may prescribe a different course of hepatitis C treatment. spoke to Maribel Rodriguez-Torres, M.D., a hepatitis C expert, to answer some of the most pressing questions on the complicated infection that is hepatitis C. After reading her explanation of the six major hepatitis C genotypes, you may want to speak to your own doctor about which treatment is most appropriate for your hepatitis C.

What should I know about the different genotypes of hepatitis C? How does my specific genotype influence my chances of getting sick, or determine the types of treatment I can receive?

Maribel Rodriguez-Torres, M.D.
Maribel Rodriguez-Torres, M.D.

The medical community recognizes six major genotypes. We have known for a long time that the genotypes reflect different genetic compositions of the virus. The major difference between the six genotypes is in their geographical location as they evolved in different parts of the world. In the Western world, the majority of patients are infected with genotype 1. Within genotype 1, there are further subcategories; the most common in the Western Hemisphere are 1a (most common) and 1b, but 1c and others have been identified. Genotype 4 is more common in Egypt and countries in the Middle East. Genotype 5 is mostly seen in Asia, while genotype 6 is mostly present in patients from the Pacific Islands, Australia and East Asia. There are also some striking differences among different countries. For example, genotype 1b is more common in Japan and genotype 3 is the most common genotype in Pakistan.

In terms of the drugs patients can take, genotype used to make a huge difference. During the era of peg-interferon and ribavirin, patients with genotype 1 had the worst efficacy results. Genotype 2 patients were the easiest to treat, and genotype 3 patients had not as good results, but still typically did better than genotype 1 patients did. Now, the drugs available today can cure the majority of genotype 1 patients. Interestingly, genotype 2 and 3 are seen more frequently in the Western world. It used to be that about 80% of patients in the U.S. had genotype 1, but that is changing. Now there are more patients with genotypes 2 and 3, although these genotypes are still the minority.

Clinicians are now most concerned for the patients that are infected with hepatitis genotype 3, because these patients do not respond as well as genotype 1 patients with the new drug combinations. The only approved drug for these patients is sofosbuvir (Sovaldi). However, patients need to take the drug for six months (as opposed to 12 weeks for genotype 2), and cure rates are still not as good as for genotype 1 or 2.

We are also now seeing more patients with genotype 4 infections in the U.S., and that used to be extremely unusual in the general population. We hypothesize that this is the result of an evolution of the protective characteristics of the hepatitis C. In other words, the more effectively we treat patients with genotype 1 virus, the more opportunity other genotypes have to disseminate.

Maribel Rodriguez-Torres is the founder and president of Fundación de Investigación (FDI), the largest clinical research center in Latin America. She received both her M.D. and her postgraduate fellowship at the School of Medicine of the University of Puerto Rico. She dedicates much of her time today to working with the government to increase access to treatment for patients without health insurance.