Some Y-DNA haplotypes occur more frequently in certain parts of the world. For example, people whose ancestors are from the western coast of Europe often share in common a small group of Y-STR markers, which is called the Atlantic Modal Haplotype.
The Atlantic Modal Haplotype is tied to the R1b haplogroup and is characterized by these Y-STR markers:
DYS19 = 14
DYS388 = 12
DYS390 = 24
DYS391 = 11
DYS392 = 13
DYS393 = 13
More information about the Atlantic Modal Haplotype can be found in Wilson et al. (2001).