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Qatari genome mapping to help prevent diseases

Doha, January 8, 2014

Genetic variations of Qatar’s native population could help doctors target interventions to reduce the prevalence of a variety of debilitating hereditary disorders, said a study.

Researchers at Weill Cornell Medical College in Qatar (WCMC-Q) and Weill Cornell Medical College New York (WCMC-NY), working with colleagues from Cornell University in Ithaca and Hamad Medical Corporation, identified 37 genetic variants in 33 genes known to play causal roles in a total of 36 diseases, including such devastating conditions as cystic fibrosis, sickle cell anemia and muscular dystrophy.

The study pointed the way to more comprehensive screening for a host of inherited diseases, which could significantly reduce their incidence.

The project, entitled ‘Exome Sequencing Identifies Potential Risks Variants for Mendelian Disorders at High Prevalence in Qatar,' sequenced the DNA of 100 Qatari nationals representing the three major ethnic subgroups of the country – the Bedouin (termed Q1 for the purposes of the study), those of Persian-South Asian descent (Q2), and those of African descent (Q3).

By analysing the individuals’ exomes – important sections of the DNA containing the code that is translated into proteins – and comparing them to the genetic data of the participants in the worldwide 1000 Genomes Project (1000G), the researchers were able to identify the variations that cause disease among the Qatari population.

All of the conditions targeted in the study were called ‘Mendelian diseases,’ which are named for Gregor Mendel, the 19th century researcher who founded genetic science. Mendelian diseases are those caused by a single mutated gene and are also known as monogenic disorders.

Dr Ronald Crystal, chairman of genetic medicine at WCMC-NY, said: “There are about 3.2 billion letters that comprise the human genome and about two per cent of those letters code for the actual proteins. This two percent is found in regions called exomes. A Mendelian or monogenic disease is caused by a change in a single letter out of the 3.2 billion.”

“The reason this is relevant for Qatar is that the structure of the society encourages a high degree of consanguineous marriage, so the frequency of these monogenic diseases is quite high.”

Pre-marital counselling and screening is one method of decreasing the likelihood of children being born with monogenic diseases.

Currently, pre-marital counselling in Qatar screens for four genetic variations out of the 37 identified in the study and incorporating the newly discovered variations into the screening process could have a significant impact, he said.

On the practical applications of the study, Dr Crystal explained: “With more comprehensive screening, people will be able to make more informed choices about whether they feel its safe to have children together.

“Alternatively, it is possible to screen the fertilised eggs for variations that cause disorders before they are implanted.

“The improved screening can also be useful for adults who can change their lifestyle to prevent themselves from developing diseases,” said Dr Crystal.

In a separate study, led by Dr Crystal, researchers focused on a variation of a gene called ApoE that makes carriers disproportionally susceptible to having increased levels of unhealthy fats called triglycerides in their blood, which is associated with disorders such as heart disease, type 2 diabetes and stroke.

The ApoE variant, termed R145C, was previously considered extremely rare, but the study found that the mutation is far more common than was realised and that it disproportionally affects people of sub-Saharan African extraction.

“These findings have important implications for African and African-derived populations all over the world, including in the United States,” Dr Crystal added. - TradeArabia News Service




Tags: Qatar | Disease | study | genetic |

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