Dr Ronald Crystal, Chairman of Genetic Medicine, Weill Cornell Medical College, New York and (RIGHT) Dr Khalid Fakhro, Postdoctoral Associate in Genetic Medicine at WCMC-Q.
DOHA: A Weill Cornell Medical College study that analysed the DNA of Qatar’s native population has discovered genetic variations that could help doctors in interventions to reduce the prevalence of a variety of debilitating hereditary disorders.
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 36 diseases, including devastating conditions such as cystic fibrosis, sickle cell anaemia and muscular dystrophy.
The study points the way to more comprehensive screening for inherited diseases, which could significantly reduce their incidence.
The project ‘Exome Sequencing Identifies Potential Risks Variants for Mendelian Disorders at High Prevalence in Qatar’ sequenced the DNA of 100 Qataris representing 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 their exomes — important sections of the DNA containing the code translated into proteins — and comparing them to the genetic data of the participants in the worldwide 1000 Genomes Project (1000G), the researchers identified variations that cause diseases among the Qatari population.
All conditions targeted in the study were so-called ‘Mendelian diseases’. Named for Gregor Mendel, the 19th century researcher regarded as the founder of genetic science, Mendelian diseases are caused by a single mutated gene and are also known as monogenic disorders.
Dr Khalid Fakhro, Postdoctoral Associate in Genetic Medicine at WCMC-Q, and Dr Juan L Rodriguez-Flores of WCMC-NY, were co-lead principal investigators for the study, which is part of projects investigating the Qatari genome led by Dr Ronald Crystal, Chairman of Genetic Medicine at WCMC-NY. The study has been accepted for publication in the journal Human Mutation, appeared online in December 2013 and will be printed this month.
Dr Crystal said, “There are about 3.2 billion letters that comprise the human genome and about two percent of these letters form the 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 3.2bn.
“The reason this is relevant for Qatar is that the structure of 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.
Parents undergo screening to see if either or both carry genetic variations that cause disease before having children.
The individuals that carry the disorder do not necessarily have the conditions, but may carry them on recessive genes.
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