‘Startle’ disease (also known as hyperekplexia), is characterised by an exaggerated reaction to unexpected stimuli, such as touch or loud noises. The startle reaction can be detected as an abnormal increase in muscle tension causing rigidity and the inability to move. During these rigid periods, breathing can stop for minutes at a time. Although rare, this disorder can have serious consequences, including infant death.

In the past, changes in one particular gene were thought to be the only major cause of this disorder.  However, a new study¹, led by Professor Mark Rees, Dr Seo Kyung Chung and Dr Rhys Thomas at ILS, College of Medicine, Swansea University and Professor Robert Harvey of the UCL School of Pharmacy has identified a number of new changes in another gene in 21 cases from the UK, Australia, Canada, France, Italy, Jordan, the Netherlands, Portugal, Spain and the USA.

These findings firmly established the second gene (GlyT2) as a major disease factor. People with GlyT2 changes also had a high-rate of early infantile breathing problems and childhood learning difficulties.

Professor Rees from the College of Medicine, Swansea University said:

“This study underpins the importance of multi-institutional research into rare childhood  disorders. The careful collection of data and clinical tracking over 20 years is now revealing opportunities to tackle this disorder and develop specific clinical care guidelines.”

Another collaborative study² led by Dr Beatriz López-Corcuera at the Universidad Autónoma de Madrid, identified one recurrent GlyT2 gene change  in individuals from Spain and the UK.

The two studies have recently been published in back-to-back articles to the Journal of Biological Chemistry :

 ¹Mutations in the GlyT2 gene (SLC6A5) are a second major cause of startle disease

²A novel dominant hyperekplexia mutation Y705C alters trafficking and biochemical properties of the presynaptic glycine transporter GlyT2