Human Genome Project Information Archive

Archive Site Provided for Historical Purposes

Sponsored by the U.S. Department of Energy Human Genome Program

Human Genome News Archive Edition
go to list of issues »

Human Genome News, July-August 1995; 7(2):2

DiGeorge Syndrome Region Cloned

Candidate Genes Identified

Researchers led by Beverly Emanuel and Marcia Budarf at Children's Hospital of Philadelphia have cloned a region of the chromosome 22 long arm containing a chromosomal breakpoint involved in DiGeorge syndrome (DGS) and have identified candidate genes spanning the breakpoint [Nature Genetics 10, 269-78 (July 1995)].

Named for endocrinologist Angelo DiGeorge, who first described the syndrome in 1965, the 22q11 microdeletion associated with DGS is believed to occur about once in 4000 to 5000 births. Children born with chromosome 22-deletion disorders share several characteristics, including cardiac defects, abnormal facies, thymic hypoplasia, cleft palate, and hypocalcemia. Region 22q11.2 deletions may be implicated in a significant proportion of newborns with heart defects.

Although patients have many different deletion endpoints, researchers found that most have a 1.5-Mb deletion [the DiGeorge chromosomal region (DGCR)]. Deletion size has not been correlated with disorder severity. To identify candidate genes spanning the minimal region critical to DGS development, researchers studied a rare DGS individual with a balanced translocation between chromosomes 2 and 22. Gene transcripts were identified by direct screening of cDNA libraries, exon amplification, cDNA selection, and GRAIL sequence analysis. Attention is now focused on two genes located directly at the breakpoint; one of these codes for a protein that resembles the androgen receptor, suggesting a possible role in developmental regulation. A complete cosmid contig of DGCR has been constructed and is now being sequenced in collaboration with Bruce Roe (University of Oklahoma).

Return to the Table of Contents

The electronic form of the newsletter may be cited in the following style:
Human Genome Program, U.S. Department of Energy, Human Genome News (v7n2).

Human Genome Project 1990–2003

The Human Genome Project (HGP) was an international 13-year effort, 1990 to 2003. Primary goals were to discover the complete set of human genes and make them accessible for further biological study, and determine the complete sequence of DNA bases in the human genome. See Timeline for more HGP history.

Human Genome News

Published from 1989 until 2002, this newsletter facilitated HGP communication, helped prevent duplication of research effort, and informed persons interested in genome research.