Viral Infections and Gene Variant Are Linked to Child Hepatitis Cases

Two small studies show that a complex combination of factors could be to blame for the puzzling cases of children with the disease.

The studies are based on a few dozen cases and have not been peer reviewed or published. They suggest that the children may have been exposed to two different viruses at the same time, including one known as adeno-associated virus 2.

The common helpers for A.A.V.2 are the adenoviruses, which have previously been found in many of the children with the mysterious hepatitis.

The scientists found that many of the children studied had a rare version of a gene that plays a role in the immune response.

In a small subset of children with this particulargene variant, dual infections with A.A.V.2 and an adenoviruses cause an abnormal immune response that damages the liver.

The researchers acknowledged that the studies were based on a small number of children in the United Kingdom and that there was no proof of a link.

Dr. Antonia Ho is an author of one of the new studies.

She said that the findings needed to be released so that other people could look for A.A.V.2 and learn more about it.

Dr. Saul Karpen, who was not involved in the research, said the findings are intriguing. He said that the study was not a conclusive one. It can make sense, but there isn't a lot of support for it.

The children's cases of the disease are rare but can be very serious. More than one thousand probable cases had been reported from 35 countries by July 8. Two percent of the children have died and five percent have required a transplant.

Many children were found to have been exposed to an adenoviruses, a group of common viruses that can cause cold or flu symptoms. If adenoviruses are involved in the cases, they may be part of the story.

Nine Scottish children with unexplained hepatitis were compared with 58 other children in control groups. The researchers were able to identify any viruses in the samples from the children.

The adeno-associated virus 2 was found in the blood of nine children and in the liver of four of them, according to the scientists. Six of the children were found to have adenoviruses, and three of them were found to have a commonviruses.

The researchers didn't detect A.A.V.2 in healthy children, in children who had adenoviruses, or in children with a known cause.

The findings from the second study are consistent with those from the first one. Many of the children had high levels of A.A.V.2 in their bodies. Many people had low levels of an adenoviruses in their sample.

The Scottish researchers found that eight of the nine children had a variant of the gene that codes for the immune response. Only 16 percent of Scottish donors have this variant.

Four of the five transplant recipients were found to have the same variant in their genes.

Sofia Morfopoulou, a computational statistician at the Great Ormond Street Institute of Child Health at University College London and an author of the second paper, said in an email that the two studies had reached the same conclusions.

It is possible that a recent resurgence of the adenoviruses may explain why doctors have noticed a sudden spike in these rare cases.

Dr. Emma Thomson is an infectious diseases physician at the Centre for Virus Research and a senior author of the Scottish study.

More studies are needed to focus on children in other countries.