The vertebrate gap junctions formed by the connexin family of transmembrane
proteins came to the attention of geneticists in 1993 with the identificat
ion of mutations linked to a form of demyelinating neuropathy Since then, s
everal other genetic disorders have been linked to mutations in specific co
nnexin genes. Also, different diseases can result from different mutations
in the same connexin gene. In addition, specific connexin knockout mice hav
e surprising phenotypes. This is leading cell biologists to look afresh at
connexins and their involvement in intercellular communication through gap
junctions, a process that seems central to coordinating cell function withi
n tissues. Here, we comment on how genetic studies are giving a new impetus
to the cell biology of gap junctions.