Aims and process

The aim of this investigation was to compare the clinical characteristics of girls and women with the common Rett syndrome mutations

Challenge - low numbers

Previous studies which have tried to investigate the extent and causes of the clinical variation in Rett syndrome have been compromised by small numbers. Because Rett syndrome only affects 1:8500 female births, even in Australia where we are studying a complete population of girls and women with Rett syndrome there are under 350 people in total. However there are much fewer people with specific individual mutations.

Solution - collect internationally

Since InterRett collects information about people with Rett syndrome from all over the world, information on much larger numbers of subjects is available on those with specific mutations.

Use the data to make comparisons

In this study we were able to use the information provided by families and clinicians to look at variation in the clinical presentation according to mutation. To do this we translated various items of information into numerical scores that we could then compare. The numerical scores relate to the clinical severity of Rett syndrome. The scores were calculated using three different scoring systems called the Kerr score, the Percy score and the Pineda score. Some of you might recognise the names - they're named after the clinicians who first used or devised these scores. The severity scores allow comparisons of severity to be made between groups of people with Rett syndrome, but aren’t that useful in relation to an individual person.

Information on the severity scores

Each of the three severity scales is different to the others, both in which aspects of Rett syndrome are considered, and in how the information for those aspects is categorised. All three severity scores include items describing:

• mobility (especially walking)
• communication and language
• hand skills and hand stereotypies
• epilepsy and seizures
• scoliosis
• head circumference