GENOMICS 32, 104 –112 (1996) ARTICLE NO. 0082 A Transcription Map in the CATCH22 Critical Region: Identification, Mapping, and Ordering of Four Novel Transcripts Expressed in Heart E LIZABETH A. L INDSAY,* P ATRIZIA R IZZU,* R ACHELE ANTONACCI,* VESNA J URECIC ,² J UAN DELM AS -M ATA,* , ² C HENG-C HI L EE ,* , ² UNG-J IN KIM ,‡ P ETER J. S CAM BLER ,§ AND ANTONIO B ALDINI* , ² ,1 * Department of Molecular and Human Genetics and ² Human Genome Center, Baylor College of Medicine, One Baylor Plaza, Houston, Texas 77030; ‡Division of Biology, California Institute of Technology, Pasadena, California 91125; and §Institute of Child Health, London, United Kingdom Received August 15, 1995; accepted December 6, 1995 ated with 22q11.2 deletions (Wilson et al., 1993). At The acronym CATCH22 is used to indicate collec- least three syndromic presentations can be associated tively a group of related phenotypes, namely velocar- with these deletions: velocardiofacial syndrome (VCFS; diofacial syndrome (VCFS), DiGeorge anomaly (DGA), Shprintzen et al., 1978; Goldberg et al., 1993), DiGeorge and conotruncal anomaly face, which are associated anomaly (DGA; DiGeorge, 1968), and conotruncal with deletions within 22q11.2 in the great majority of anomaly face (Kinouchi et al., 1976; Takao et al., 1980). patients. A deletion map has allowed us to delimit a The great majority of patients show an interstitial dele- smallest region of deletion overlap, considerably tion that spans a segment of 2– 4 Mb (Lindsay et al., smaller than the commonly deleted region. We have 1993; 1995a,b). However, a smallest region of deletion mapped within this region the chromosomal break- overlap (SRDO, 300–400 kb) has been identified be- point of a balanced translocation patient presenting cause of the presence of chromosomal breakpoints in with a DGA/VCFS phenotype, making this region the patients with unbalanced translocations that result in strongest candidate for the location of the gene(s) re- terminal deletions. The SRDO was defined by deletion sponsible for the disease phenotype. We report a sys- mapping and FISH analysis (Lindsay et al., 1993; Hal- tematic gene search in this region and show the pres- ford et al., 1993; Fig. 1A). Although the CATCH22 ence of at least six distinct transcripts, two of which group of phenotypes is highly variable, it has not been have been previously described. The region searched found to correlate with extent of deletions (Lindsay et was approximately 270 kb; therefore, an average of one al., 1995a,b; Levy-Mozziconacci et al., 1994). In particu- transcript every 45 kb was found. We generated eight lar, individuals from the same family, who presumably new ESTs and mapped two ESTs present in public have the same deletion, may have different phenotypes databases. All six transcripts are expressed in heart, (Holder et al., 1993; Lindsay et al., 1995a,b). The source an organ involved in 70– 80% of CATCH22 patients. We show that the multimethod approach to search for ex- of such variability is unknown, and the data available pressed sequences is effective and indeed necessary do not seem to support a classical contiguous gene syn- for a comprehensive search and provides molecular drome mechanism (Schmickel, 1986). The report of a tools for further characterization of the potential patient with an incomplete DGA/VCFS phenotype and genes identified.  1996 Academic Press, Inc. a balanced translocation (Augusseau et al., 1986) sug- gests that the chromosomal breakpoint generates haploinsufficiency of one or more genes responsible for INTRODUCTION at least part of the phenotype. We have mapped the chromosomal breakpoint in this patient (ADU) within The acronym CATCH22 (cardiac anomaly, abnormal the SRDO (Lindsay et al., 1993). Two genes have been face, thymic hypoplasia, cleft palate, hypocalcemia, and identified so far in the SRDO: TUPLE1 (Halford et al., chromosome 22 deletions) has been proposed to sum- 1993), a putative transcription regulator mapped ap- marize the various phenotypic signs that may be associ- proximately 200 kb distal to the ADU breakpoint, and DGCR2/IDD (Demczuk et al., 1995; Wadey et al., 1995), 1 To whom correspondence should be addressed at Department of a putative cell surface protein and potential adhesion Molecular and Human Genetics, Baylor College of Medicine, One receptor gene mapped about 10 kb distal to the ADU Baylor Plaza, T936, Houston, TX 77030. Telephone: (713) 798-6519. Fax: (713) 798-5386. E-mail: baldini@bcm.tmc.edu. breakpoint. Recently, one or possibly two transcripts 104 0888-7543/96 $18.00 Copyright  1996 by Academic Press, Inc. All rights of reproduction in any form reserved. / 6r0f$$3908 01-18-96 11:37:20 gnmas AP-Genomics