I have mentioned before the apparent distinction between west and east Iranians in terms of haplogroup J/R1a frequencies, with high ratios in Persians and Kurds, and low ones in Pathans, and this seems to be reinforced here; the Tajiks are speakers of Persian (hence "western") but trace their ancestry to the east of the modern country of Iran, and in-between Persians and eastern Iranians.
The absence of R1a in this Kurdish sample, coupled with high J frequency parallels the situation in the Kurdish Anatolian settlement studied by Gokcument et al., as well as the Georgian Kurmanji sample studied by Nasidze et al. On the other hand, R1a is present in the Kurmanji samples from Turkey and Turkmenistan in the latter study, as well as in the aforementioned Kurdish sample from Iran by Grugni et al. and the Kurdish sample from Turkmenistan studied by Wells et al. I'd say that there is potential variation of this haplogroup within Kurdish groups, which might be worth further exploration.
It would also be very interesting to study the haplogroup I chromosomes from this region. Do they represent historical introgression from Europe, or are they, perhaps, local basal clades that reinforce the idea of a relic distribution of I in West Asia, prior to the migration into Europe, that was recently suggested by the discovery of IJ* chromosomes in Iran by Grugni et al.?
Annals of Human Biology, 2013; Early Online: 1–7
Y-chromosome variation in Tajiks and Iranians
Boris Malyarchuk et al.
Aim: The purpose of this study was to characterize Y-chromosome diversity in Tajiks from Tajikistan and in Persians and Kurds from Iran.
Method: Y-chromosome haplotypes were identified in 40 Tajiks, 77 Persians and 25 Kurds, using 12 short tandem repeats (STR) and 18 binary markers.
Results: High genetic diversity was observed in the populations studied. Six of 12 haplogroups were common in Persians, Kurds and Tajiks, but only three haplogroups (G-M201, J-12f2 and L-M20) were the most frequent in all populations, comprising together 60% of the Y-chromosomes in the pooled data set. Analysis of genetic distances between Y-STR haplotypes revealed that the Kurds showed a great distance to the Iranian-speaking populations of Iran, Afghanistan and Tajikistan. The presence of Indian-specific haplogroups L-M20, H1-M52 and R2a-M124 in both Tajik samples from Afghanistan and Tajikistan demonstrates an apparent genetic affinity between Tajiks from these two regions.
Conclusions: Despite the marked similarities between Y-chromosome gene pools of Iranian-speaking populations, there are differences between them, defined by many factors, including geographic and linguistic relationships.