We employed exon trapping and large-scale genomic sequence analysis of two
bacterial artificial chromosome clones to isolate genes from the region bet
ween the IGLC and BCR in chromosome 22q11.2. At the time these studies were
initiated, one previously identified gene, GNAZ, was known to map to this
region, Two genes, RTDR1 and RAB36, were cloned from this portion of 22q11,
which is heterozygously or homozygously deleted in pediatric rhabdoid tumo
rs of the brain, kidney and soft tissues. RTDR1 is a novel gene with a slig
ht homology to a yeast vacuolar protein. RAB36 is a member of the Rab famil
y of proteins. A series of primary rhabdoid tumors with chromosome 22q11 de
letions were screened for mutations in the coding sequences of RTDR1, GNAZ
and RAB36, but did not demonstrate any disease-specific alterations. Recent
ly, INII, which maps to the distal portion of the deletion region in 22q11,
was identified as the candidate rhabdoid tumor suppressor gene. Further st
udies of RTDR1 and RAB36 are required to determine whether their absence co
ntributes to the progression of rhabdoid tumors. Alternatively, these genes
may be candidates for other diseases that map to human chromosome 22. (C)
2000 Elsevier Science B.V. All rights reserved.