Normal vs Homozygous vs Heterozygous

If 23&me provides provides the variants for a given rs#, how do you figure if normal, homozygous, or heterozygous?

Ex: rs1800562, Variants=A or G
I happen to be A/G and already know I’m heterozygous, but how do you know if it’s a new rs#? I’ve tried searching to locate a site that will clearly show, but it’s just not to be found sometimes.

What am I missing? Where do I learn how to read the SNPs?


The raw data that you receive from 23andMe does not include information about the variant allele. It contains the RSID, Chromosome, gene location and your Genotype at each gene location. Typically, the variant allele will be one of the 2 alleles that make up your genotype. (This is not always so because sometimes the variant allele is described on a different chromosome strand than the genotypes were)

For the SNP HFE rs1800562, the minor allele is A: Livewello, dbSNP, Ensembl

So if the raw data shows your genotype as AG, then you only have one copy of the variant allele and this is what makes you Heterozygous. If your genotype had been AA, then you would have 2 copies of the variant allele and you would be Homozygous. If your genotype had been GG, you would have no copies of the variant allele.

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I am not a genetics expert, but I have been studying SNPs for 3 years now. You pretty much have to see what the experts deem the mutant allele. The problem is that sometimes, the experts have differing opinions. For example, there is significant variance in what experts believe is the mutant allele for various MAOA SNPs, and it leads to a lot of head scratching when you read various opinions. At this point, you have to look for new scientific studies pinpointing certain alleles as being more violent than others in order to get any kind of confirmation.

Honestly, I think the most accurate results entail looking at genome wide association studies (GWAS) on places like PubMed. Anyone who thinks a certain allele is bad but does not have real world information is just guessing. Granted, genomics is a whole lot of guessing at this point. The rise of precision medicine will probably help us as we search for cause and effect among the alphabet soup of personal genomics.