ABSTRACT
 
IDENTIFICATION ON CHROMOSOME 8q11 OF AN AUTOSOMAL PRECURSOR OF THE VCY2 GENE, MAPPED WITHIN THE AZFc LOCUS OF THE Y CHROMOSOME AND INVOLVED IN MALE INFERTILITY
 
L. Stuppia 1,2, S. Pintor 1, V. Gatta 1, Palka C. 1, Calabrese G. 1,3, Palka G. 1,3

1 Dept. Biomedical Sciences, University "G. D'Annunzio", Chieti, Italy

2 ITOI-CNR, Bologna, Italy

3 Human Genetics Division, Pescara Hospital, Italy
 

About 10% of infertile males show microdeletions of the Y chromosome involving three loci (AZFa, b, c). Several genes have been mapped within these loci, and X-linked or autosomal homologous for some of these have been identified. We report the identification in 8q11 of a precursor of the VCY2 gene, mapped within AZFc. Southern Blot analysis with a specific VCY2 probe evidenced signals both in male and in female samples, in addition to the main Y-specific band, suggesting the presence of an autosomal or X-linked homologous. Search in databases showed an high VCY2 homology with BAC clones mapped in 8q11. Sequence analysis using the BLAT program detected the putative gene Beyla, encoding for four possible alternative mRNA. A BLAST search evidenced a complete homology of Beyla C with a transcript from human testis (FLJ40156), suggesting that Beyla C represents the actual active gene. The genomic organization of Beyla C was confirmed by PCR with specific primers and direct sequencing. Align

ment of Beyla C and VCY2 sequences allowed to hypothesize the following process: a region of 8q, containing L1 elements, was transposed on the Y chromosome, giving origin to one G amplicon within AZFc. This step likely occurred during the primate evolution, since VCY2 is present on the Y chromosome of chimpanzee. In a second step, the Beyla C gene underwent an inverted duplication, giving origin to VCY2 and TTY4 genes, showing novel transcripts, only partially similar to the original Beyla C mRNA. Finally, the G amplicon underwent duplications, producing the multiple copies of VCY2 and TTY4 genes. This model of origin of two Y-linked genes from a single autosomal gene represent a novel mechanism, different from those so far described for other Y-linked genes.
 
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Abstracts will be published by Elsevier (Annales de Génétique)