Holt–Oram syndrome is an autosomal dominant disorder that affects bones in the arms and hands and often causes heart problems. The syndrome may include an absent radial bone in the forearm, an atrial septal defect in the heart, or heart block. It affects approximately 1 in 100,000 people.
Gap junction alpha-1 protein (GJA1), also known as connexin 43 (Cx43), is a protein that in humans is encoded by the GJA1 gene on chromosome 6. As a connexin, GJA1 is a component of gap junctions, which allow for gap junction intercellular communication (GJIC) between cells to regulate cell death, proliferation, and differentiation. As a result of its function, GJA1 is implicated in many biological processes, including muscle contraction, embryonic development, inflammation, and spermatogenesis, as well as diseases, including oculodentodigital dysplasia (ODDD), heart malformations, and cancers.
Transcription factor GATA-4 is a protein that in humans is encoded by the GATA4 gene.
ACTC1 encodes cardiac muscle alpha actin. This isoform differs from the alpha actin that is expressed in skeletal muscle, ACTA1. Alpha cardiac actin is the major protein of the thin filament in cardiac sarcomeres, which are responsible for muscle contraction and generation of force to support the pump function of the heart.
Paired-like homeodomain transcription factor 2 also known as pituitary homeobox 2 is a protein that in humans is encoded by the PITX2 gene.
Homeobox protein Nkx-2.5 is a protein that in humans is encoded by the NKX2-5 gene.
Homeobox D10, also known as HOXD10, is a protein which in humans is encoded by the HOXD10 gene.
T-box transcription factor TBX5, is a protein that in humans is encoded by the TBX5 gene. Abnormalities in the TBX5 gene can result in altered limb development, Holt-Oram syndrome, Tetra-amelia syndrome, and cardiac and skeletal problems.
Hematopoietically-expressed homeobox protein HHEX is a protein that in humans is encoded by the HHEX gene and also known as Proline Rich Homeodomain protein PRH.
Myosin heavy chain, α isoform (MHC-α) is a protein that in humans is encoded by the MYH6 gene. This isoform is distinct from the ventricular/slow myosin heavy chain isoform, MYH7, referred to as MHC-β. MHC-α isoform is expressed predominantly in human cardiac atria, exhibiting only minor expression in human cardiac ventricles. It is the major protein comprising the cardiac muscle thick filament, and functions in cardiac muscle contraction. Mutations in MYH6 have been associated with late-onset hypertrophic cardiomyopathy, atrial septal defects and sick sinus syndrome.
T-box transcription factor 2 Tbx2 is a transcription factor that is encoded by the Tbx2 gene on chromosome 17q21-22 in humans. This gene is a member of a phylogenetically conserved family of genes that share a common DNA-binding domain, the T-box. Tbx2 and Tbx3 are the only T-box transcription factors that act as transcriptional repressors rather than transcriptional activators, and are closely related in terms of development and tumorigenesis. This gene plays a significant role in embryonic and fetal development through control of gene expression, and also has implications in various cancers. Tbx2 is associated with numerous signaling pathways, BMP, TGFβ, Wnt, and FGF, which allow for patterning and proliferation during organogenesis in fetal development.
Heart- and neural crest derivatives-expressed protein 2 is a protein that in humans is encoded by the HAND2 gene.
Transcription factor GATA-5 is a protein that in humans is encoded by the GATA5 gene.
Zinc finger protein ZFPM2, i.e. zinc finger protein, FOG family member 2, but also termed Friend of GATA2, Friend of GATA-2, FOG2, or FOG-2, is a protein that in humans is encoded by the ZFPM2 and in mice by the Zfpm2 gene.
Homeobox protein goosecoid(GSC) is a homeobox protein that is encoded in humans by the GSC gene. Like other homeobox proteins, goosecoid functions as a transcription factor involved in morphogenesis. In Xenopus, GSC is thought to play a crucial role in the phenomenon of the Spemann-Mangold organizer. Through lineage tracing and timelapse microscopy, the effects of GSC on neighboring cell fates could be observed. In an experiment that injected cells with GSC and observed the effects of uninjected cells, GSC recruited neighboring uninjected cells in the dorsal blastopore lip of the Xenopus gastrula to form a twinned dorsal axis, suggesting that the goosecoid protein plays a role in the regulation and migration of cells during gastrulation.
Atrial Light Chain-2 (ALC-2) also known as Myosin regulatory light chain 2, atrial isoform (MLC2a) is a protein that in humans is encoded by the MYL7 gene. ALC-2 expression is restricted to cardiac muscle atria in healthy individuals, where it functions to modulate cardiac development and contractility. In human diseases, including hypertrophic cardiomyopathy, dilated cardiomyopathy, ischemic cardiomyopathy and others, ALC-2 expression is altered.
Iroquois-class homeodomain protein IRX-5, also known as Iroquois homeobox protein 5, is a protein that in humans is encoded by the IRX5 gene.
TBX20 (gene) is a member of the T-box family that encodes the transcription factor TBX20. Studies in mouse, human and fruitfly have shown that this gene is essential for early heart development, adult heart function and yolk sac vasculature remodeling and has been associated with congenital heart diseases. Tbx20 was also shown to be required for migration of hindbrain motor neurons and in facial neurons was proposed to be a positive regulator of the non-canonical Wnt signaling pathway.
Retinal homeobox protein Rx also known as retina and anterior neural fold homeobox is a protein that in humans is encoded by the RAX gene. The RAX gene is located on chromosome 18 in humans, mice, and rats.
tinman, or tin is an Nk2-homeobox containing transcription factor first isolated in Drosophila flies. The human homolog is the Nkx2-5 gene. tinman is expressed in the precardiac mesoderm and is responsible for the differentiation, proliferation, and specification of cardiac progenitor cells. This gene is named after the character Tin Woodman who lacks a heart, as flies with nonfunctional tinman genes have cardiac deformities.
