In the 1 March issue of Nature (Vol. 410, No. 6824, 01 March 2001), researchers from Baylor College of Medicine in Texas pinpoint the gene behind one of the most common genetic diseases to affect humans: DiGeorge syndrome.
The disease results in a broad spectrum of symptoms, including heart abnormalities, disruption of the immune system and facial morphology. DiGeorge syndrome affects around 1 in 4,000 babies born, and next to Down syndrome it is the most common genetic cause of heart defects.
DiGeorge syndrome is caused by deletions of large sections of DNA from our smallest chromosome: chromosome 22. Up to one tenth of this chromosome’s 33 million DNA base pairs can be missing from the genome of DiGeorge syndrome patients. A large number of genes lie within this section of DNA (known as 22q11.2), but until now researchers have been unable to pinpoint the exact gene, or genes, which directly cause the disease.
Antonio Baldini and colleagues used state-of-the-art genetic techniques to test a number of candidate genes in a mouse model of DiGeorge syndrome. This model allows them to identify a gene known as Tbx1— a control gene that switches on the expression of other genes during development—as being responsible for the main cardiac symptoms of the disease. The finding brings to an end the long search for a gene involved in DiGeorge syndrome, and provides scientists with insight into both the disease, and the normal development of complex organs like the heart.
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