Genetic evidence that ZFY is not the testis-determining factor.
In mammals, the testis determining gene (TDF), present on the Y chromosome, induces the undifferentiated gonads to form testes. The position of TDF on the human Y chromosome has been defined by analysing the genomes of XX males and XY females, generated by abnormal genetic exchange between the X and Y chromosomes in male meiosis. In this way TDF has been localized close to the pseudoautosomal region shared by the sex chromosomes, in the distal Y-specific region. A recently cloned human gene, ZFY, has many features indicating that it is TDF. For example, ZFY encodes a protein with many features of a transcription factor including a domain with multiple 'zinc-finger' motifs. Less consistent with ZFY being TDF, however, is the presence of a very similar gene, ZFX, on the X chromosome, and the presence of a sequence related to ZFY on autosomes in marsupials. We now report on analysis of XX males lacking ZFY. In these individuals, the male phenotype could be explained by a mutation in a gene 'downstream' of ZFY in the sex-determining hierarchy; but in that case there should be no exchange of material between the X and Y chromosomes. We find on the contrary that in 4 XX males lacking ZFY, there is exchange of Y-specific sequences next to the pseudoautosomal boundary, redefining the region in which TDF must lie.
Palmer
M S
MS
Human Molecular Genetics, Imperial Cancer Research Fund, Lincoln's Inn Fields, London, UK.
Sinclair
A H
AH
Berta
P
P
Ellis
N A
NA
Goodfellow
P N
PN
Abbas
N E
NE
Fellous
M
M
D015139:Blotting, Southern; D002874:Chromosome Mapping; D015342:DNA Probes; D005260:Female; D005784:Gene Amplification; D005796:Genes; D006801:Humans; D007621:Karyotyping; D008297:Male; D009693:Nucleic Acid Hybridization; D012016:Reference Values; D012732:Sex Determination Analysis; D013737:Testis; D014998:Y Chromosome
D015342:DNA Probes