The Angor language is unusual in that it distinguishes gender in the second- and third-person dual and plural (you and they), but not in the singular. It is not clear if Dera does the same.
The most promising external links are with the Sepik and Torricelli languages. The pronoun for "I" is reconstructed as *wan for both proto-Senagi and proto-Sepik, while the Angor masculine dual and plural pronominal suffixes -fa- and -mu- appear to reflect the proto-Sepik and proto-Torricelli dual and plural pronominal suffixes *-p and *-m.
^ abFoley, William A. (2018). "The Languages of the Sepik-Ramu Basin and Environs". In Palmer, Bill (ed.). The Languages and Linguistics of the New Guinea Area: A Comprehensive Guide. The World of Linguistics. Vol. 4. Berlin: De Gruyter Mouton. pp. 197–432. ISBN978-3-11-028642-7.
Ross, Malcolm (2005). "Pronouns as a preliminary diagnostic for grouping Papuan languages". In Andrew Pawley; Robert Attenborough; Robin Hide; Jack Golson (eds.). Papuan pasts: cultural, linguistic and biological histories of Papuan-speaking peoples. Canberra: Pacific Linguistics. pp. 15–66. ISBN0858835622. OCLC67292782.