Table 2. Collagen gene variants, their mechanism, and how they relate to CTS.

CTS - carpal tunnel syndrome, CTC - connective tissue components

Gene Variant	Mechanism	Relation with CTS
Presence of the COL11A1 gene's T allele (rs1676486) [31,32].	Decreased formation of the α1(XI) collagen chain.	The etiology of CTS may be related to type XI collagen production.
The existence of variations (rs3753841, rs1676486 and rs1746744) in the T-C (AGGG) section of the COL5A1 and COL11A1 genes [31,33].	Altered type V and XI collagen formation as a result of abnormal mRNA stability	The cause of CTS is because of the mechanical changes that alter the properties of tendons and other CTC inside the CT
A variation in the COL11A1 gene at position rs3753841 that involves a change from T to C at a single nucleotide site [32].	The change in exon 52 results in a switch from leucine to proline in the α1(XI) chain at position 1323, causing a non-synonymous substitution.	This can impact the formation of type XI collagen, causing disruptions to the structure and performance of newly formed collagen fibers. These disruptions within the CT, could potentially contribute to the development of CTS.
A variation in the COL11A1 gene at position rs1676486 that involves a change from T to C at a single nucleotide site [32].	This variation in exon 62 causes a change in the amino acid from proline to serine in the α1(XI) chain at position 1535, leading to a non-synonymous substitution.	This can impact the formation of type XI collagen, causing disruptions to the structure and performance of newly formed collagen fibers. These disruptions within the CT, could potentially contribute to the development of CTS.
The COL1A1 gene has a Minor variant of the T allele (designated as rs1800012, with the notation G/T), which codes for type I collagen's α1 chain [33,34].	In intron 1 of COL1A1's Sp1 binding site, replacing tyrosine with a guanine nucleotide increases the transcription factor Sp1's binding affinity, leading to heightened COL1A1 gene expression and overproduction of type I collagen homotrimers comprised of three α1 chains.	It is believed that a rise in the levels of type I collagen homotrimers in tendons and other CTC may alter their mechanical properties and make them more susceptible to injury. This alteration could also play a role in the generation of higher pressure in the CT.