LEFT–RIGHT HEART

About one child in 125 is born with a congenital heart defect – a problem with the development of the heart itself or of the major blood vessels that connect to the heart. Professor Shoumo Bhattacharya's studies of the mouse gene Cited2 suggest that many such defects may be due to problems with the development of the heart's asymmetry.

During embryonic development, the heart begins as a single tube that then 'loops' and contorts, eventually forming the four chambers of the adult heart. This is necessary for two parallel circulations to develop: the right side of the heart delivering blood to the lungs, the left side delivering blood to the body. Common congenital heart defects arise when this development goes awry, leading to, among other things, holes in the heart, closed valves, or misalignment of the great vessels.

Genes that control the asymmetry of the heart may underlie common congenital heart defects. Professor Bhattacharya, a Wellcome Trust Senior Research Fellow at the Wellcome Trust Centre for Human Genetics in Oxford, has found that the Cited2 gene plays a key role in the left–right patterning of the mouse heart. Highly inbred (genetically very similar) mice lacking Cited2 had severe heart defects – the left side of the heart developed as a right side, a condition called right isomerism that also occurs, rarely, in humans. Non-pedigree mice lacking Cited2 had a range of less severe heart defects, such as holes in the heart and misalignment of the great vessels.

As the defects seen in the latter mice are similar to the diverse range of congenital heart defects seen in humans – who are also 'non-pedigree' – the research suggests problems with the heart's left–right patterning may be at fault in both cases.

See also

• Left-right heart (Feature)

External links

• Bamforth SD et al. Cited2 controls left–right patterning and heart development through a Nodal–Pitx2c pathway. Nat Genet 2004;36(11):1189–96.