A new gene test will greatly improve the speed and clarity of diagnosis for a complex range of genetic disorders, known as rasopathies, including Noonan Syndrome.
The new test has been developed by molecular diagnostic testing company NewGene in collaboration with the South West Thames Regional Genetics Service at St George’s Healthcare NHS Trust in London, the specialist centre for Noonan Syndrome and associated hereditary disorders in the UK.
Noonan Syndrome is an inherited disease passed down through families that causes abnormal development in children which is associated with a broad range of clinical features.
Approximately 80% of those affected by Noonan syndrome suffer from congenital heart defects. Other effects can include feeding problems in babies, distinctive facial and physical features, speech and hearing defects, delayed development and behavioural problems
Although some features are more frequently associated with particular syndromes, variable presentations make it difficult to provide a definitive clinical diagnosis. Correctly identifying the disorder is essential to ensure that appropriate care and monitoring is provided and to preclude unnecessary investigations.
The research laboratories at St George’s have worked for over 10 years to clone the genes for Noonan Syndrome. Currently genetic testing of suspected Noonan cases is carried out on a sequential basis by testing for one disorder or gene and then another until a mutation is identified to confirm the diagnosis. This is both time consuming and costly and delays the determination of the best clinical care pathway for patients.
The new work carried out by NewGene and the specialists at St George’s has resulted in the development of a new one step test that provides large scale parallel screening of all 12 genes associated with Noonan disorders in one panel.
This comprehensive new assay will now allow a refined diagnosis to be made more quickly than has been possible previously. This approach will also be far cheaper to the NHS than screening all available genes in separate assays.
Professor Michael Patton, Medical Advisor for the Noonan Syndrome Association UK said “Since the discovery of new genes associated with Noonan disorders, it has become increasingly difficult and expensive to undertake full genetic testing for the syndrome.
“However, the development of the next generation sequencing test at NewGene and St George’s hospital represents a major advance in the diagnosis of Noonan syndrome”.
A positive test result will determine which disorder is applicable enabling medical interventions appropriate for that specific disorder can be highlighted more quickly.
It will enable clinical management to be more targeted reducing the need for batteries of expensive and protracted specialist investigations, many of which require ward admission.
This will assist in decision making regarding growth hormone treatment, provision of special education for delayed development, treatment using fresh frozen plasma to avoid life threatening haemorrhage and haematological monitoring.
Noonan spectrum disorders affect around 1 in 1,000 live births. The early identification of a pathogenic mutation will also facilitate informative genetic counselling and confirmation testing in other affected individuals in the family. A definitive diagnosis would allow families early use of patient support groups such as the Noonan Syndrome Association (NSA).
St George’s is the only centre registered with UKGTN to offer analysis for Noonan and Leopard syndromes and is likely to provide the full national need for these and other related syndromes of the RAS MAPK pathway.
Source: St George’s Healthcare NHS Trust