In homozygous animals, the brachyury mutation is lethal at around embryonic day 10 due to defects in mesoderm formation, notochord differentiation and the absence of structures posterior to the forelimb bud (Dobrovolskaïa-Zavadskaïa, 1927).

Tbxt was cloned by Bernhard Herrmann and colleagues[9] and proved to encode a 436 amino acid embryonic nuclear transcription factor.

[10] The gene brachyury appears to have a conserved role in defining the midline of a bilaterian organism,[11] and thus the establishment of the anterior-posterior axis; this function is apparent in chordates and molluscs.

As such, it is primarily responsible for the genotype that codes for tail formation due to its observed role in axial development and the construction of posterior mesoderm within the lumbar and sacral regions.

[17][13] ‌TBXT transcribes genes that form notochord cells, which are responsible for the flexibility, length, and balance of the spine, including tail vertebrae.

Because of this, the two elements are paired together in the replication process, leading up to the formation of a stem-loop structure and an alternative splicing event that fundamentally influences transcription.

This is also how lesions are able to occur at all–the stalled transcription process serves as a beacon for TC NER proteins to ascertain the location of the stem-loop.

[27] TBXT-Δexon6 falls into this category, as it is an isoform that lacks the ability to process the code that enables proper tail formation in TBXT-containing organisms.

Other common examples of influential isoforms include those involved in AMP-induced protein kinase that insert phosphate groups into specific sites of the cell depending on the subunit.

[28] The first insertion of the AluY element occurred approximately 20-25 million years ago, with the earliest hominid ancestor known to exhibit this mutation being the Hominoidea family of apes.

Over time, the mutation occurred more regularly due to the influence of natural selection and fixation to stabilize and expand its presence in the ape gene pool prior to the eventual speciation of homo sapiens.

[29] There are several potential reasons for why taillessness has become the standard phenotype in the Hominidae taxa that offset the genetically disadvantageous aspects of tail mitigation, but little is known with certainty.

[43] In addition to its role in common cancers, brachyury has been identified as a definitive diagnostic marker, key driver and therapeutic target for chordoma, a rare malignant tumor that arises from remnant notochordal cells lodged in the vertebrae.

[19] Overexpression of brachyury has been linked to hepatocellular carcinoma (HCC, also called malignant hepatoma), a common type of liver cancer.

Exon 6's excision fundamentally affects the manner in which TBXT-encoded cells divide, distribute information, and form tissue because of how stem-loop sites create genetic instability.

Because both of these developmental disorders result in the displacement of organs and other bodily mechanisms, they are both directly related to outright malfunction of the kidney, bladder, and nervous system.