|(G;G)||2||Some increase in peripheral neuropathy risk in older adults taking folate|
rs1801198, also known as c.776G>C, p.Arg259Pro and R259P, is a common variant in the TCN2 gene on chromosome 22. Note that in older (pre-2003) literature this variant was known as c.775G>C.
A relatively small study published in 2016 of ~170 adults over 60 years of age concluded that rs1801198(G;G) individuals have significantly (~3x) higher risk of peripheral neuropathy, even with a normal vitamin B-12 status, and especially if their folate intake is >800 micrograms/day (i.e. 2 times the Recommended Dietary Allowance, with a reported OR of 6.9, CI:1.31- 36.36). In other words, excess folate (including folic acid) is more likely to lead to a burning, tingling or numbness in the hands and feets of older adults who happen to be rs1801198(G;G) genotypes. There was no difference in neuropathy risk between genotypes when folate intake was less than 800 micrograms per day; overall, the odds of neuropathy were 3-fold higher for GG genotypes than for CC genotypes (OR 3.33, CI: 1.15-9.64).[PMID 27733392]
|Disease Association||Defects in TCN2 are the cause of transcobalamin II deficiency (MIM:275350). This results in various forms of anemia.|
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|CLNSRC||OMIM Allelic Variant UniProtKB (protein)|
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|qualified_impact||Insufficiently evaluated not reviewed|
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