In the ongoing study of the unique behavior known as "Meowchatting",
previously reported to be due to morphological changes in the
hypothalamus region of the brain, researchers recently announced
isolation and chromosomal cytolocation of the gene involved, as well
as some insights into the origin of the gene.
Familial linkage analysis indicated that there was most likely a single
gene involved in determining a persons meow-chat ability, and that the
gene showed an autosomal dominant inheritance pattern. This was
somewhat of a surprise, as many researchers had assumed that the trait
was sex-linked. Environmental factors therefore most likely are
involved in the activation of the gene during development. Autosomal
dominant traits mean that only one copy of the gene is required for the
trait to be expressed, and that people with one parent who was a
meow-chatter had a roughly 50% chance of being meow-chatters themselves.
The gene has tentatively been assigned the symbol IZAKAT, although final
approval is still pending. The function of the wild type (which confers no
meowchat ability) IZAKAT is not yet known, although it is speculated to
be involved in language ability and creativity.
Human-feline somatic cell hybrids gave a rough cytolocation assigning
the gene to chromosome 5p. Scientists then used fluorescent in
situ hybridization (FISH) analysis to give a tighter chromosomal
assignment, and found that the gene shows a high affinity for the probe
used in FISH studies, allowing for a highly accurate cytogenetic
localization assignment. The gene has been localized to the
5p15.2 - 5p15.3, also known as the cri-du-chat critical region.
Cri-du-chat is a syndrome (MIM:123450) associated with a chromosomal
deletion and characterized by microcephaly, facial deformities, low IQ,
and a high-pitched cat like cry in newborn. There is some speculation
that the absence of IZAKAT in those with CDC syndrome may be a leading
factor in the syndrome.
Early homology studies indicate that IZAKAT is highly conserved, and in
fact the human gene seems to be closely related to similar genes in the
domestic cat, felis domestica, an unexpected result. While the standard
explanation in such cases is that the gene is a holdover from the common
ancestor of cats and humans, the lack of strong homology to closer
relatives of cats or human throws this theory into doubt.
One possible, but highly controversial, explanation suggests
that the mutation from wild type (no meowchat ability) to the mutant
(meowchat ability) form of IZAKAT was caused by permanent insertion of a
retrovirus common to cats into a germ cell at the locus for IZAKAT,
creating a highly altered gene. In this scenario, a retrovirus inserts
itself into the genome of one organism, becoming permanently incorporated
into the genome of that organism. In some circumstances, a retrovirus
may take part of the host genome with it when it jumps back out. In the
event of a zoonotic infection, when a virus common in one species
infects members of a different species, it is possible for some portion
of the cat genome to be incorporated into that of a human. To some
extent, should this scenario prove true, meowchatters tend to sound like
cats because, to some extent, they *are* cats.
This controversial assertion also explains the accounts of spontaneous
and addictive meowchatting by those with no family history of
meowchatting. These events may represent instance of new infection of
humans by the cat-DNA carrying virus when humans are exposed to
particularly infectious cats. While scientists have so far been
unable to isolate this theoretical virus from humans, the virus
appears to be harmless and relatively stable in humans, as those who
become meowchatters after hanging around with infectious cats tend to be
in good health otherwise. While some concern has been expressed over
the possibility of a hidden epidemic of cross-special infection of
meowchatting, one leading researcher in the field said "Yuz gots
ta have lotsa smurgles wif da kat. Iz nuffin fer nermal hoomins
ta worry bout.", and added that permanent alteration to the genome
was rare as germ cells are not the usual target of the virus.