New DNA test for diagnosing diseases linked to childhood

Each year, between 20,000 and 40,000 children worldwide are born with congenital cataracts. The disease can arise following a maternal infection or be inherited as an isolated abnormality. Congenital cataracts can also appear as a symptom of more than 100 rare diseases, making mutations in the 115 genes associated with congenital cataracts useful as diagnostic markers for the illnesses.Diagnosing those rare diseases previously proved a lengthy, costly, and inconclusive process involving numerous clinical assessments and taking a detailed family history.ploying new DNA sequencing technology, called targeted next-generation sequencing, researchers at the University of Manchester in the United Kingdom sped up diagnosis to a matter of weeks by testing for mutations in all 115 known congenital cataracts genes at one time.In 75 per cent of the 36 cases tested, the DNA test determined the exact genetic cause of congenital cataracts. In one case, the DNA test helped diagnose a patient with Warburg Micro syndrome, an extrely rare disease that is marked by an abnormally small head and the development of severe epilepsy, among other medical issues. Having a clear diagnosis allowed for genetic counselling and appropriate care to be delivered quicker than previously possible without the test. There are many diseases that involve congenital cataracts but finding the exact reason was always difficult, Grae Black, of the University of Manchester, said. Even with a family history, diagnosing those rare diseases was always a bit of a shot in the dark. In the course of their work, the researchers also found previously un-described mutations linked to cataract formation. There is hope that our work may one day provide more insight into the development and treatment of age-related cataracts, a leading cause of blindness worldwide, lead author Rachel Gillespie, University of Manchester, said.The test was made available to United Kingdom patients through the country’s National Health Service in Decber 2013. Infants and children who have congenital cataracts can be tested as well as prospective parents with a history of the condition who wish to evaluate the risk to their child. Results generally take about two months.

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