What's more, there's a suburb of my home town called Gezina. Herewith a brief history lesson: at the end of the 19th century there were two little independent Dutch-speaking republics in inland South Africa which might have lived happily ever after except that gold was discovered in the more northerly one. Its president was Paul Kruger, and its seat of government was Pretoria; Gezina was his wife's name, so she got the suburb named after her.
It wasn't a nn for Gertruida (the local form ...) to my knowledge - she had it as a given name in its own right.
By the way, old President Kruger had three given names: Stephanus Johannes Paulus, of which he used the third. I believe that this is the German custom - ie a German named Karl-Heinz would be called Heinz, whereas an Englishman named CharlesHenry would be called Charles. Am I right, Satu, or am I raving (not unusual ...)?