Pain and reduced function in the jaw joint and chewing muscles, affecting about 5% of people in the US and twice as many women as men. Both variants here turned up only when the study looked at women separately — and one of the two, genome-wide significant in discovery, failed to replicate.
Temporomandibular joint disorder (TMD) is pain and reduced function in the temporomandibular joint — where the jawbone meets the skull — and the muscles used for chewing. It affects roughly 5% of people in the United States, and is about twice as common in women as in men.
Sanders et al. 2017 ran a genome-wide study in 10,153 participants (769 cases, 9,384 controls) from the US Hispanic Community Health Study/Study of Latinos, then tested the strongest signals in a meta-analysis of four more cohorts — one more from the US, and one each from Germany, Finland and Brazil — adding 1,911 cases and 6,903 controls.
The combined, both-sex analysis found nothing genome-wide significant. Splitting the discovery cohort by sex did: two loci reached significance in women specifically. RXP2 (relaxin/insulin-like family peptide receptor 2, chromosome 13) had a borderline replication in the meta-analysis's female participants. DMD — the dystrophin gene, on the X chromosome, the same gene that when severely disrupted causes Duchenne muscular dystrophy, though this is an intronic common variant with no such consequence — was genome-wide significant in discovery but did not replicate in the meta-analysis at all. Both associations point the same direction: the reported allele lowers risk rather than raising it.
The paper notes a mechanistic thread worth stating plainly rather than overselling: DMD is part of the dystrophin-glycoprotein complex that gives muscle fibers their structure, alongside a separate gene (SGCA) the same study flagged as suggestive-but-unreplicated at a third locus — a plausible connection to a disorder centered on the chewing muscles, not a settled one.
TMD is diagnosed by clinical examination of jaw function and pain, sometimes with imaging — not by genotype. Treatment ranges from conservative measures (rest, heat, a bite guard) to physical therapy to, in persistent cases, dental or surgical intervention, chosen by a dentist or specialist based on symptoms and exam findings. Nothing on this page changes that.
The two variants here carry different strength of evidence, and the page says so rather than treating them the same. RXP2's association had a real, if borderline, replication in independent women. DMD's reached genome-wide significance in the discovery cohort alone and did not hold up in the replication meta-analysis — a real result from a real study, but one that did not survive an independent test, and this page reports that rather than quietly dropping it or presenting it as equally solid.
Both loci were found only when the study analysed women and men separately — TMD's roughly two-to-one sex skew is well established, but whether these particular genetic findings explain any of that skew, or are a smaller-sample artifact of splitting the cohort, is not something this single study can settle on its own.
What a 23andMe/AncestryDNA export or raw VCF can and can't tell you about Temporomandibular Joint Disorder comes down to these specific, well-studied positions — not a diagnosis.
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Temporomandibular Joint Disorder. MyGeneLog™. https://www.mygenelog.com/conditions/temporomandibular-joint-disorder
No. TMD is diagnosed by clinical examination of jaw function and pain, sometimes with imaging. These variants come from a genome-wide association study and are not used diagnostically.
The discovery study analysed men and women together and found nothing genome-wide significant, then analysed the sexes separately and found two loci in women specifically. TMD itself is about twice as common in women as men, but whether that connects to these particular findings is not settled.
No — this page states that difference rather than treating both the same. RXP2's association had a borderline independent replication. DMD's reached genome-wide significance in the discovery cohort alone and did not replicate when tested in four independent cohorts.
No. This is a common variant in an intron of the DMD gene, unrelated to the rare, severe mutations that cause Duchenne muscular dystrophy. The paper notes DMD's general role in muscle fiber structure as a plausible — not proven — connection to a disorder centered on the chewing muscles.
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