Dissection of a complex phenotype by gene identification, gene function analysis and comparative sequencing between man and mouse

Andreas Winterpacht, Ph.D
Institute of Human Genetics
University of Hamburg
Butenfeld 42
D-22529 Hamburg
Germany
telephone: ++49-40-42803-5535
fax: ++49-40-42803-5128
email: winterpacht@uke.uni-hamburg.de
prestype: Platform
presenter: Andreas Winterpacht, Ph.D.

Winterpacht, Andreas (1); Schlickum S. (1); Pfarr N. (1,2); Steglich C. (1); Heller R. (1); Endele, S.(1)
(1) Institute of Human Genetics, University of Hamburg, D-22529 Hamburg, Germany; (2) Children´s Hospital, University of Mainz, D-55101 Mainz, Germany

The Wolf-Hirschhorn syndrome (WHS) is a complex and variable malformation syndrome associated with the deletion of the terminal short arm of one chromosome 4. The WHS critical region (WHSCR) has been confined to a 165 kb gene rich region on chromosomal subband 4p16.3. Clinical and cytogenetic data indicate that WHS is a contiguous gene syndrome, which means that haploinsufficiency of more than one gene in the affected chromosome region contribute to the phenotype. In order to elucidate the etiology and pathogenesis of this syndrome our studies aim at identifying all genes and regulatory regions contributing to the phenotype.

We sequenced the corresponding WHSCR in the mouse genome and applied interspecies sequence comparison, computer assisted analysis of the present human sequence, as well as functional studies. Two known and three novel genes were identified. In addition, we detected several EST matches as well as predicted exon sequences that did not correspond to any of these transcription units. By extensive RT-PCR analysis and rapid amplification of cDNA ends (RACE) we could demonstrate that most of these sequences correspond to a single novel transcript which is expressed at a low level in several tissues. The transcript contains repetitive sequences, does not display any significant open reading frame and undergoes complex alternative splicing. The 5´-end of the transcript overlaps with exon 1 of a gene on the opposite strand indicating that it might function as an antisense transcript.

By detailed expression and functional studies we are currently investigating which of the genes contribute to the WHS phenotype. Moreover we elucidate the possibility of coregulation of these genes.