Homozygous deletion of 4q35.1. (A) In the Elijah cell line, delineation of the deleted segment in 4q35.1 revealed a small deletion of 251 kb between the potential candidate genes ARGBP2 and SNX25. (B-C) Both genes truncated in a cryptic fusion between SNX25 exon 15 and ARGBP2 intron and between ARGBP2 exon 18 and SNX25 intron. Both genes splice to cryptic splice acceptor sites in the opposite transcriptional orientation. As a consequence of the deletion, ARGBP2 loses a crucial COOH terminal domain that may interfere with its binding to CBL and SNX25 also results in the truncation of the COOH terminal domain. Deletion of ALP gene, mapped between ARGBP2 and SNX25, is also detected. (D) Truncated SNX25 mRNA is expressed using RT-PCR in Elijah cell line (exons 12-15), whereas no expression of the deleted SNX25 mRNA is present (exons 16-19). On the contrary, expression of both mRNAs (exons 12-15 and exons 16-19) are present in the cell lines without deletion of SNX25 (MD901, SUPB15, and HRC57).