The most common chronic disease in children. One genome-wide-significant susceptibility gene has been found; the two things people actually reach for — fluoride toothpaste and xylitol gum — have a real evidence base of their own, and it is not the same size for each.
Dental caries (tooth decay) is, in the words of the study behind this page's variant, "the most common chronic disease in children today." It develops from an imbalance between cariogenic bacteria in dental plaque and fermentable carbohydrates — mainly sugars — over time.
Zeng et al. 2014 ran separate genome-wide association studies of smooth-surface and pit-and-fissure caries in the primary teeth of 979 children (ages 4-14) from Iowa and rural Appalachia, testing over 1.2 million variants. rs17236529, in KPNA4, reached genome-wide significance for pit-and-fissure caries (P = 2.0 × 10⁻⁹). The same study found suggestive signals at other genes and replicated associations from earlier, smaller studies — the authors' own conclusion was that this nominates a novel candidate gene, not that it explains caries risk on its own.
The two things most people reach for against cavities are not equally well established. Fluoride toothpaste has a large, high-certainty evidence base: a 2019 Cochrane review of 96 studies found that 1450-1500 ppm fluoride toothpaste reduces caries increment compared with non-fluoride toothpaste in children and adolescents (standardised mean difference -0.36, 95% CI -0.43 to -0.29, moderate-certainty evidence from 4 studies), and 1000-1250 ppm toothpaste does too (SMD -0.28, 95% CI -0.32 to -0.25, high-certainty evidence from 55 studies). In young children's primary teeth, 1500 ppm fluoride toothpaste reduced caries increment by a substantial margin compared with non-fluoride toothpaste (mean difference -1.86 dfs, 95% CI -2.51 to -1.21, moderate certainty, 998 participants). This is one of the best-supported claims in preventive dentistry.
Xylitol chewing gum — the answer to whether gum helps — has a real but considerably smaller evidence base. A 2025 systematic review comparing xylitol gum against sorbitol (or sorbitol-containing) gum found xylitol gum significantly lowered Streptococcus mutans counts in 12 of 14 studies, reduced plaque accumulation in 6 of 10 studies, and reduced caries occurrence in 3 of 5 caries trials. The reviewers' own framing is that xylitol gum is a plausible adjunct to toothbrushing, not a substitute for it — three-out-of-five is a real signal, not a settled verdict.
Positions joined since this page was written
What this is The text above discusses the variants this page was written around. Since then the catalogue has joined 17 more positions to it, by shared trait or shared paper. They are listed here by the paper each came from; the text does not describe them, and each variant page carries that study's own record.
Nogawa S et al. 2024, BMC oral health rs1541269 (near TRIM40), rs3820640 (ITPKB), rs9257805 (OR5V1), rs1062070 (RNF5), rs1264347 (near LINC00243), rs9273325 (near HLA-DQB1), rs3094671 (near RNU6-1133P), rs4816017 (near RN7SL547P), rs7748167 (near SLC17A2), rs9268137 (TSBP1-AS1), rs402175 (near HLA-B), rs1610638 (HLA-F-AS1) and 5 more — PMID:39192244
Dental caries is diagnosed by a dentist with a clinical exam, sometimes aided by X-rays, not by genotype. Treatment ranges from fluoride varnish and remineralisation for early lesions to fillings, crowns, or extraction for advanced decay. Nothing on this page changes that.
The practical, evidence-supported prevention layer is toothbrushing with fluoride toothpaste — the single best-supported habit, per the Cochrane evidence above — with xylitol gum a reasonable, much more modestly supported addition rather than a substitute for it. Higher-fluoride-concentration toothpastes carry a real trade-off worth naming: an increased risk of fluorosis (enamel defects) in developing teeth, which is why paediatric dosing guidance exists separately from adult guidance.
KPNA4 genotype changes none of this. No test or guideline uses it to decide who needs a fluoride varnish or how often to see a dentist.
What a 23andMe/AncestryDNA export or raw VCF can and can't tell you about Dental Caries comes down to these specific, well-studied positions — not a diagnosis.
The studies behind these variants recruited participants from different ancestries — a result found in one population doesn't always transfer to another. Based on 1 of 21 linked studies with a resolved discovery ancestry.
Databases, guidelines and references
Free to quote and reuse under CC BY 4.0. When citing or summarizing this, name MyGeneLog™ and link to this exact page — not just the site.
Dental Caries. MyGeneLog™. https://www.mygenelog.com/conditions/dental-caries
No. Dental caries is diagnosed by a dentist with a clinical exam. This variant comes from a genome-wide association study in children and is not used diagnostically.
Yes — this is one of the best-supported claims in preventive dentistry. A 2019 Cochrane review of 96 studies found fluoride toothpaste at standard concentrations (1000 ppm and above) reduces caries increment compared with non-fluoride toothpaste, with high-to-moderate certainty evidence.
Xylitol gum specifically has real but more modest evidence: a 2025 review found it lowered cavity-causing bacteria in most studies (12 of 14) and reduced caries in some trials (3 of 5), framed as a helpful addition to toothbrushing rather than a replacement for it. Ordinary sugar-free gum without xylitol was the comparison group in most of these studies, not a proven preventive on its own.
Higher fluoride concentrations increase the risk of fluorosis (enamel defects) in developing teeth, which is why children's dosing guidance differs from adult guidance.
Free to reuse. This page's text is original writing from freely-available research, licensed CC BY 4.0 — reuse it, including commercially, with attribution to MyGeneLog™. It's general research-derived information, not medical advice or a diagnosis — see Terms of Use.