How many MAOA alleles are there?

Question

The question is about the human gene MAOA.

I've seen MAOA-H and MAOA-L mentioned in papers.

The page https://www.ensembl.org/Homo_sapiens/Gene/Summary?db=core;g=ENSG00000189221;r=X:43654907-43746824 does not describe the gene alleles as far as I can tell.

There is a base sequence of exons provided at https://www.ensembl.org/Homo_sapiens/Gene/Sequence?db=core;g=ENSG00000189221;r=X:43654907-43746824 however since all the nucleotides are already written in I don't understand which base pairs can vary and which are always the same.

So is there a reference that describes in detail all the known MAOA alleles and which base sequences they have?

Answer 1

I recommend searching a resource such as dbVar that is targeted towards human genomic variation, rather than serving up slices of the human reference genome.

The human reference genome is a single sequence that, as you say, does not try to represent genetic variation. It is merely a reasonably good representation of what a single haploid human genome copy might be expected to look like.

I searched MAOA on dbVar and found 426 different variants (alleles observed via DNA sequencing) that have been described. A minority of these have been annotated as either pathogenic or benign (see "Clinical Assertion" column), but for the most part we don't know what effect these alleles have, if any.

For richer information about specific disorders related to MAOA mutations (alleles), you might also consider looking at OMIM. However this will only include instances of alleles thought to affect phenotypes.