Structural variations between great ape and human chromosomes due to pericentric 
inversions and translocations have created at apparent controversy during the 
reconstruction of hominoid phylogeny. One such variation involves human 
chromosome 5, which is equivalent to chromosome 4 in chimpanzee and orangutan 
but equivalent to segments of chromosomes 4 and 19 in gorilla. Obviously, 
neither banding patterns nor centromeric indecies in these chromosomes match. 
The pathological condition of cri du chat syndrome is due to the cytogenetic 
deletion of band p15.2 of chromosome 5. Is this region involved during 
pericentric inversion of apes chromosome 4? We used a human cosmid probe for cri 
du chat syndrome as a phylogenetic marker in search of the aforementioned 
question. The genomic sequences for cri du chat syndrome region were conserved 
in chimpanzee (PTR4) and orangutan (PPY4) but displayed a positional divergence 
in gorilla on chromosome 19(GG019). In addition, we used a human cosmid DNA 
probe for DiGeorge syndrome which is located on chromosome 22 band q11.2 and was 
conserved within band 23q11.2 in apes. The loci specific human genomic probes 
may help to describe the inversions and translocations for other chromosomes.