Bernard has a summary of this paper by Tassi et al, 2017 called "Genome Diversity in the Neolithic Globular Amphorae and the spread of the Indo-European languages".
|GAC burial by G. Osipowicz via (Message to Eagle)|
These particular genomes come from a megalithic grave in Northeastern Poland. One thing to keep in mind is that very little is known about the GAC, and secondly what is known is that there is some regional diversity in economy and burial practices. A single individual in this group appears to have some amount of steppe-related DNA, which is only surprising to those who might have expected more.
The GAC individuals, minus the one, are notable for having elevated HG ancestry of similar proportions to Middle Neolithic Sweden, Hungary and Iberia Chalcolithic. But they don't not seem to share a composition similar to local populations.
In fact, if GAC migrated from anywhere, it seems that they migrated from the West to the East including some analysis of rare ancestry, but certainly their maternal profiles.
"The GAC samples are clearly separated from those populations, and show instead a closer relationship with the western, Late Neolithic, Bell Beaker population (electronic supplementary material, figure S12).Violet Volken from Northern France? Clearly they are not derived from the steppe region as once believed by Gimbutas and many others. Interestingly though, these very 'Western' looking people do end up in the Northern Pontic Steppe, or at least their influences do. This would presumably mean that GAC was intrusive.
The median-joining network  (electronic supplemen- tary material, figure S13) shows GAC sequences falling in haplogroups H, J, K, U and W. The relationships between the GAC and other populations of the same time period are evi- dent (electronic supplementary material, figure S14, inset d), especially with the population from Sweden and, although less so, with the Baalberge population from Germany."
Another thing that's puzzling is their highly mobile economy. Maybe another time.
And a strange comment:
"However, in this case, the substantial contribution of males should at least result in some degree of similarity between GAC and Yamnaya at the nuclear level, which did not emerge in this study. In both cases, a trans- mission of cultural traits from the Pontic steppes to the GAC, and later further West, is conceivable and not ruled out by our data; further archaeological work, including studies of other GAC sites, may shed additional light on this."If I were to assume they had y-chromosomal DNA of these GAC individuals, and they are looking at disparity between nuclear DNA and paternal haplogroups of Yamnaya and GAC, then what are they looking at?