CDH18 rs6451575: What Your Genotype Means

What each genotype means

What rs6451575 is and where it sits

A SNP is a one-letter difference in DNA that can occur among people in the same genomic position. For rs6451575, the alleles recorded in dbSNP are C and T, producing three commonly discussed genotype combinations: CC, CT, and TT. The rsID is a stable identifier used by databases such as dbSNP, Ensembl, and the GWAS Catalog to refer to this location, even when researchers use different genome assemblies or describe the surrounding region in slightly different ways. rs6451575 is located on chromosome 5 in the CDH18 genomic region. Public variant databases are the best sources for the current assembly-specific position and whether the marker is annotated within a gene feature or nearby regulatory sequence. A location inside or near a gene does not, by itself, demonstrate that the variant changes the gene’s protein or activity. Many trait-associated SNPs are statistical markers that travel with another nearby causal variant through linkage disequilibrium. For this reason, rs6451575 should be understood primarily as a population-genetics marker. Its association with alcohol-related behavior does not establish that the SNP itself directly controls alcohol metabolism, drinking preference, or addiction risk.

What the CDH18 gene does

CDH18 encodes cadherin 18, a member of the cadherin family of cell-adhesion proteins. Cadherins generally help cells recognize and adhere to neighboring cells. Their activity can contribute to the organization of tissues and to communication between cells, although the specific biological consequences of variation near CDH18 depend on the variant, tissue, developmental stage, and regulatory context. The presence of an association near CDH18 does not mean that CDH18 has been proven to be an alcohol-use gene in the same way that alcohol-metabolizing genes such as ADH1B and ALDH2 have well-established biochemical roles. rs6451575 is not generally used to calculate how quickly a person breaks down ethanol or acetaldehyde. A genome-wide association signal can arise because a marker affects gene regulation, because it is linked to another functional variant, or because of statistical and population-specific factors. At present, the public evidence does not establish a simple mechanism connecting rs6451575, CDH18 activity, and alcohol consumption. The gene provides useful biological context, but it does not turn this SNP into a clinical test.

What research has associated it with

The cataloged association is with alcohol-consumption behavior, described here as alcohol consumption quality. This wording refers to a statistical trait association rather than a laboratory measurement of alcohol metabolism or a medical diagnosis. Studies of alcohol-related traits often use self-reported consumption, frequency, beverage patterns, or other behavioral measures. Those measures are influenced by culture, availability, age, sex, socioeconomic conditions, mental health, medications, and many other genetic and environmental factors. The evidence level for this record is moderate, not definitive. A moderate classification supports treating the finding as a research association while retaining substantial caution about replication, effect size, ancestry, phenotype definition, and possible confounding. Even a reproducible genome-wide association usually explains only a small part of the variation between individuals. The available evidence does not show that rs6451575 alone causes heavy drinking, protects against alcohol-related harm, or identifies alcohol use disorder. It also does not establish that changing behavior according to this genotype would improve health. The finding is best viewed as one small statistical signal among many influences on alcohol-related behavior.

How common is this variant?

The catalog describes rs6451575 as common. Both the C and T alleles are represented in population databases, and the three corresponding genotypes—CC, CT, and TT—can therefore occur in people whose ancestry is represented in those datasets. Exact allele and genotype frequencies can differ across populations because of ancestry, sampling, quality-control filters, and the reference genome dataset used. A frequency observed in one ancestry group should not automatically be applied to everyone. gnomAD and dbSNP provide population-stratified information where available, but database categories are not a perfect census of the world’s populations. Some groups remain underrepresented in large genomic databases, and apparent differences can partly reflect sampling or technical factors. Common also does not mean important for most people. A common allele can have a very small statistical association, while uncommon variants can sometimes have larger effects in specific medical conditions. For rs6451575, frequency information supports the idea that the marker is widespread, but it does not make the alcohol-related association individually predictive.

What a reader can—and cannot—do with this result

A consumer genetic result for rs6451575 can tell you which pair of alleles was called at this location, assuming the testing platform measured the SNP accurately. It can also be used to compare your result with the populations and research studies cited in public databases. That is the appropriate level of interpretation: a research-oriented association concerning alcohol-consumption behavior. The result cannot tell you how much alcohol you will drink, whether you will develop alcohol use disorder, whether you are safe to drink, or whether you will experience alcohol-related disease. It cannot replace a clinical assessment, and it should not be used to justify starting, stopping, or changing a medication. Alcohol-related health risks depend on many genetic and non-genetic factors, including drinking pattern, liver health, pregnancy status, sleep, mental health, and interactions with medicines. If a result causes concern, discuss it with a qualified healthcare professional or genetic counselor. The most useful health decisions come from personal medical history and evidence-based clinical care, not from this single common SNP.

Frequently asked questions

Sources & further reading

Related variants in CDH18