It was discovered prior to many of the SNPs now used to identify subclades of R1b and references to it can be found in some of the older literature.
The AMH is the most frequently occurring haplotype amongst human males in Atlantic Europe.
It is characterized by the following marker alleles: It reaches the highest frequencies in the Iberian Peninsula, in Great Britain and Ireland.
In the Iberian Peninsula it reaches 70% in Portugal as a whole, more than 90% in NW Portugal and nearly 90% in Galicia (NW Spain), while the highest value is to be found among Spain and the Basques.
The AMH 1.15 set of haplotypes is also referred to as the Atlantic modal cluster or AMC.