  We considered the fourth catalog of gamma-ray point sources produced by the
Fermi Large Area Telescope (LAT) and selected only jetted active galactic
nuclei (AGN) or sources with no specific classification, but with a
low-frequency counterpart. Our final list is composed of 2980 gamma-ray point
sources. We then searched for optical spectra in all the available literature
and publicly available databases, to measure redshifts and to confirm or change
the original LAT classification. Our final list of gamma-ray emitting jetted
AGN is composed of BL Lac Objects (40%), flat-spectrum radio quasars (23%),
misaligned AGN (2.8%), narrow-line Seyfert 1, Seyfert, and low-ionization
nuclear emission-line region galaxies (1.9%). We also found a significant
number of objects changing from one type to another, and vice versa
(changing-look AGN, 1.1%). About 30% of gamma-ray sources still have an
ambiguous classification or lack one altogether.
