July 9 (Bloomberg) -- Scientists have decoded the gene sequence of human chromosome 7, a step they said will help research on hereditary deafness, cystic fibrosis and some cancers, according to a study in the July 10 Nature journal.

Investigators filled in gaps from preliminary mapping at Washington University's Genome Sequencing Center in St. Louis. Chromosome 7 is one of the 23 that make up the human genetic code.

``We get a much better picture of the overall landscape of how chromosomes are put together and organized'' because chromosome 7 is the largest to be decoded, Richard Wilson, director of the Genome Sequencing Center and co-author of the study, said in an interview.

The work should give researchers better ``access to the genes'' that cause diseases including white-blood-cell cancers such as leukemia, Wilson said.

Chromosome 7 is also the location of the gene that causes cystic fibrosis, which affects about 30,000 people in the U.S., and the disorder Pendred syndrome, which causes about 10 percent of hereditary deafness. The Pendred syndrome gene was discovered in a 1997 U.S. National Institutes of Health study.

The chromosome contains about 1,150 genes. Researchers have posted information on its sequence in a public genome database since the start of the project in 1994.

``It's a matter of months to seeing fruitful results in research, and it takes a decade to see medical results,'' said Wilson. ``For treatments or cures it's typically a longer pathway because you're talking about drug development, companies making decisions about what to pursue, and regulatory approval.''

Gene maps now exist for six human chromosomes, including 14, 20, 21, 22 and Y.

Last Updated: July 9, 2003 15:12 EDT