LONDON -- The flurry of discoveries of new genes for inheriteddisease continued right up to the end of 1993, with twoannouncements concerning research supported by Britain's MedicalResearch Council. In one announcement, a consortium of researchersat the MRC Molecular Haematology Unit in Oxford, the Institute ofMedical Genetics in Cardiff and two groups in the Netherlands saidthat it had identified a gene for the inherited disease tuberoussclerosis.
The second announcement, regarding a family of genes thought tocontrol sperm production in humans and several animals, came fromthe MRC's Human Genetics Unit and the Fertility Problems Clinic ofthe Department of Surgery at Edinburgh University in Scotland. Bothdiscoveries were published in Thursday's issue of the journal Cell.
Tuberous sclerosis affects about 10,000 people in Britain. Many casesare due to new genetic mutations, but in families with one affectedparent, children have a 50 percent chance of inheriting the disease.Its symptoms include learning difficulties, epilepsy and a range ofother medical problems, including tumors (usually non-malignant)in various organs.
Working with families with a history of tuberous sclerosis, theresearchers used positional cloning to isolate the gene of chromosome16. Peter Harris, leader of the MRC's team, said that in the short termthe goal is to develop a test for tuberous sclerosis. "In the long term,it will lead to a better understanding of this disorder, which mayresult in the development of treatments for this distressingcondition," he said.
The researchers also believe the gene may be involved in regulationcell growth and may play a more general role in the development oftumors.
The second announcement concerned work on men with severesperm-production problems. Screening in the Fertility ProblemsClinic at the Western General Hospital showed that 15 percent ofthese men carried a mutation or deletion in the Y chromosomeknown as the azoospermia factor (AZF). Ma Kun, a student in theMRC's Human Genetics Unit, identified the gene family most likely tobe AZF. The team, led by Anne Chandley and Howard Cooke, alsoestablished the genetic sequence of some members of the family.
It turns out that the gene in question is involved in the production of"information" protein in the cell. Mutations in this gene may cause aloss of information that, in turn, could reduce sperm formation in asignificant number of men with no other apparent cause ofinfertility.
Members of the same gene family also exist in other species,including mice, gorillas, sheep and bulls.
Chandley said the discovery of the gene could be the first steptoward diagnosing male infertility through DNA analysis. "We hopethat in the long term, understanding the gene function will help us todevise novel methods of male contraception as well as finding waysto treat male infertility," she said.
-- Michael Kenward Special to BioWorld
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