  We report the discovery by the Large Area Telescope (LAT) onboard the Fermi
Gamma-ray Space Telescope of high-energy gamma-ray emission from the peculiar
quasar PMN J0948+0022 (z=0.585+/-0.001). Contrary to the expectations, the
optical spectrum of this quasar shows only narrow lines [FWHM(Hbeta) ~ 1500
km/s] and the typical characteristics of narrow-line Seyfert 1 type galaxies.
However, the strong radio emission and the flat spectrum suggest the presence
of a relativistic jet, which can now be confirmed by the detection of MeV-GeV
photons. PMN J0948+0022 is therefore the first radio-loud narrow-line Seyfert 1
quasar to be detected at gamma-rays and the third type of gamma-ray emitting
AGN, after blazars and radiogalaxies.
