Which Caucasian languages have glottalized consonants?

All three major families of Caucasian languages—the South Caucasian (Kartvelian), the Northwest Caucasian (Abkhazo-Adyghian), and the Northeast Caucasian (Nakho-Dagestanian)—feature glottalized consonants.123

In these languages, glottalized consonants (also known as ejectives) are produced with an accompanying closure of the glottis, which is the space between the vocal cords. Across these language groups, stops typically occur in a series of three types: voiced, voiceless aspirated, and glottalized. In the Kartvelian languages specifically, both stops and affricates possess these voiced, voiceless, and glottalized varieties. Similarly, the Nakho-Dagestanian languages maintain this three-way distinction in their stop systems.13