It has been demonstrated that a Drosophila homeobox-containing gene called 'tinman' is expressed in the developing dorsal vessel and in the equivalent of the vertebrate heart.

Furthermore, abundant expression of Csx, the presumptive mouse homolog of tinman, is observed only in the heart from the time of cardiac differentiation.

Patients with NKX2-5 mutations commonly present AV conduction block and atrial septal defects (ASD).

[16] During embryogenesis, NKX2-5 is expressed in early cardiac mesoderm cells throughout the left ventricle and atrial chambers.

In Nkx2-5 knock out mice, cardiac development halts at the linear heart tube stage and looping morphogenesis disrupted.

NKX2-5 operates in a positive feedback loop with GATA transcription factors to regulate cardiomyocyte formation.

[24] This article incorporates text from the United States National Library of Medicine, which is in the public domain.