An American couple are facing murder charges in Qatar over the death of their young adopted daughter, in a case which lawyers and medical experts in the US say is based on shoddy evidence and poor science. A campaign has been launched in the US over the arrest of Matthew and Grace Huang in January after the death of their nine-year-old daughter, Gloria, who was adopted from Ghana. According to the California Innocence Project (CIP), a US-based organisation which works on what it believes to be wrongful prosecutions, the Huangs have been denied bail, and their two other children - also adopted from African countries - have not been allowed to leave the country. If found guilty, the Huangs could face the death penalty under Qatari law, although there has been an effective moratorium on executions for the last 10 years. The Qatari public prosecutor's office was unavailable for comment on the case. The CIP cited Qatari investigative reports which suggested that the couple "bought" their children in order to harvest their organs or conduct medical experiments, and accused them of starving their daughter. The medical examiner told a court that Gloria appeared emaciated. But a report prepared by an independent pathologist in the US, who specialises in child autopsies, found no solid evidence to support the conclusions of the Qatari medical examiner's investigation. "This is a case of faulty science and what appears to be racial and cultural misunderstandings by the Qatari officials about American norms regarding international adoptions," said a statement from the CIP. 'A combination of factors' Gloria's death certificate, issued by Qatar's supreme council of health, listed the causes of death as "cachexia and dehydration". Cachexia, commonly known as "wasting syndrome", can produce symptoms that look similar to starvation, including weight loss and muscle atrophy. It can be caused by a range of conditions, including congestive heart failure and autoimmune diseases. According to the independent report, however, the medical examiner in Doha did not test for any of these. Gloria had previously been diagnosed with a low white blood cell count, which could suggest an underlying medical condition, according to a source familiar with her medical history. She also suffered from giardia when she was adopted, an infection which is difficult to completely eliminate. Doctors also did not test her "vitreous humour", the clear gel inside the eyes, which is a standard way to diagnose dehydration. Her bodily fluids were tested only for drugs, poison and semen, and all tests were negative. The medical examiner said in court that starvation or malnutrition could have contributed to her death. But family acquaintances have said in affidavits that Gloria was walking around her house the night before she died, which would be virtually impossible for a child dying of starvation. The Huangs have acknowledged that their daughter suffered from an eating disorder, which they attribute to an early childhood spent in extreme poverty in Ghana. "The report does not indicate that the many fluid, blood and tissue analyses that were necessary to rule out other potential causes were ever done," said the independent report, prepared by Dr Janice Ophoven. A copy of the report was reviewed by Al Jazeera. "The likely reality is that Gloria's death was caused by a combination of factors and that there is not evidence that her parents were intentionally starving her." 'Hereditary traits' People working with the Huangs have also suggested that the case was fuelled by "cultural misunderstandings". The Huangs are of Chinese descent, and their three children are from Ghana and Uganda. The CIP said investigative reports wonder why the couple adopted children who were not "good-looking" and did not share their "hereditary traits". The reports also suggest that the Huangs may have been involved in human trafficking, the CIP says. Yet this sort of adoption is quite common in the US: American families have adopted nearly 17,000 children from African countries since 1999, according to State Department statistics. The Huangs' three children were all adopted through an established agency. The CIP said that the Huangs moved to Doha last year with their three children. Matthew was an engineer working on a water purification project related to the 2022 World Cup, which will be hosted in Qatar. The couple have denied the charges, and are scheduled for another hearing when Qatar's courts return from their summer recess. "The family remains concerned by the Qatari officials who fail to understand the pain of losing a child to a rare and deadly syndrome" said the David House Agency, a California-based organisation which is working with the family. "They are also disappointed that the Qatari courts have denied the bail of Matthew and Grace and have refused to allow their other children to leave Qatar to be cared for by extended family members.