  Quasi-periodic oscillations (QPOs) are coherent peaks of variability power
observed in the X-ray power spectra (PSDs) of stellar mass X-ray binaries
(XRBs). A scale invariance of the accretion process implies they should be
present in the active galactic nuclei. The first robust detection was a $\sim
1$ hr periodicity in the Seyfert galaxy RE J1034+396 from a $\sim 90$ ks
XMM-Newton observation, however, subsequent observations failed to detect the
QPO in the $0.3-10.0$ keV band. In this talk we present the recent detection of
the $\sim 1$ hr periodicity in the $1.0-4.0$ keV band of 4 further
low-flux/spectrally-harder observations of RE J1034+396 (see Alston et al
2014). We also present recent work on the discovery of a QPO in the Seyfert
galaxy, MS 22549-3712, which again is only detected in energy bands associated
with the primary power-law continuum emission (Alston et al 2015). We conclude
these features are most likely analogous to the high-frequency QPOs observed in
XRBs. In both sources, we also see evidence for X-ray reverberation at the QPO
frequency, where soft X-ray bands and Iron K$\alpha$ emission lag the primary
X-ray continuum. These time delays may provide another diagnostic for
understanding the underlying QPO mechanism observed in accreting black holes.
