Since the Alanic kingdom lasted for a few centuries before the Alans migrated to Central and Western Europe, I would expect that the bulk of their men were actually of North Caucasian stock. Only a minority (among the elite mostly) would have belonged to the original Central Asian lineages (presumably R1a, and I would say of the
Z93 branch).
If genetic traces of the Alanic invasions are to be found in modern Western Europe I would look for areas that have both G2a1a and R1a-Z93. Neither subclade is supposed to be found in Western Europe, and only a small Alanic contingent who settled there 1500 years ago would explain them.
Checking the FTDNA G project for matches in Central and Western Europe, I found G2a1a people in Hungary, Italy, England and Spain. There are notably G2a1a1a3 with close matches in North Ossetia in Spain (surname Merino), Italy (Jacoe, Meli, Spatafore) and England (Moody, Price and Wright), and a similar cluster of G2a1a2 also in Spain (Gonzalez, Villarreal, Nanez), Italy (Filippelli) and England (Reid, Litton).
- The Spanish matches are from Castile and Andalusia, where the Alans passed.
- Three of the Italian members have roots in Calabria, and the fourth in Sicily, which corresponds to the last known 5th-century Alanic settlements, after leaving Tunisia.
- The Alans never went to England, but they settled in what would become Normandy, so it's only natural that some ended up in England. France is notoriously undersampled, but I expect to find even more matches there, especially in the Seine and Rhône valleys.
In the R1a project I only found isolated R1a-Z93 members in northern Italy, Germany (3x), the Netherlands, England and Scotland. But also interestingly in Tunisia, the Alani's last major settlements before they dispersed around Italy. Otherwise there are quite a few R1a-Z93 in Poland and Hungary, but they belong to deeper subclades with matches in Kazakhstan, and are probably descended from later Scythian migrations.